HK1116981B - Metal base circuit board, led, and led light source unit - Google Patents

Description

Metal base circuit board, LED and LED light source unit

Technical Field

The present invention relates to a foldable metal base circuit board ensuring heat dissipation and electrical insulation properties and having excellent electromagnetic wave shielding properties, and a Light Emitting Diode (LED) and an LED Light source unit using the same, and more particularly, to an LED Light source unit suitable for a backlight of a liquid crystal display device.

Background

In recent years, a circuit board for mounting a semiconductor is required to have a smaller size, higher density and higher performance, and a problem arises in that how to dissipate heat generated from a semiconductor element or the like in a narrow space due to the smaller size and higher power of the semiconductor element or the like. In particular, in the fields including the power supply field and the automotive electronics decoration field, a metal base circuit board in which a metal foil is bonded to a metal plate with an insulating layer interposed therebetween to form a circuit has been used because of its excellent heat dissipation properties.

However, since the base substrate of the metal base circuit board is generally 1.0mm to 3.0mm thick, it is difficult to make the metal base circuit board thin, and the installation position is limited. Further, since the structure is such that a thin insulating layer is interposed between the metal plates, there is a problem that noise is easily generated and malfunction of the module is easily caused.

In order to provide noise shielding and heat dissipation, for example, a metal-based multilayer substrate in which an upper layer circuit board having a circuit is laminated on the entire surface or a part of the metal-based circuit board with an adhesive is known (see patent document 1).

In such a configuration, since the adhesive layer having poor thermal conductivity is present between the metal plate and the upper substrate, when a high power element is mounted on the upper circuit pattern, there is a problem that heat dissipation is insufficient, the temperature of the element rises, and malfunction occurs.

In order to solve the above-described problem of heat dissipation, a metal base circuit board having an insulating layer with high thermal conductivity is known (see patent document 2).

However, since the metal plate is thick and cannot be attached to the case body such as a curved case, heat dissipation of the insulating layer cannot be sufficiently exhibited, and since the metal plate cannot be bent, a large space is required for installation, and the module cannot be downsized.

On the other hand, a metal base circuit board in which an insulating layer made of an epoxy resin or the like filled with an inorganic filler is provided on a metal plate and a circuit pattern is formed thereon has excellent heat dissipation and electrical insulation properties, and is used as a circuit board for electronic equipment such as a communication device and an automobile on which a high heat generating electronic component is mounted (see patent document 3).

If the metal base circuit board can be arbitrarily bent, the restriction of the mounting position to be usually provided in the flat portion is relaxed, and the metal base circuit board can be brought into close contact with the side surface or the bottom surface of the case, the staggered layer or the curved surface by adhesion, bonding, screw fixation or the like, thereby realizing the miniaturization of the electronic device on which the high heat generating electronic component is mounted. Further, if the metal base circuit board itself can be made thin, it can be inserted into or fixed to a narrow space, and therefore, it is possible to make an electronic device in which a high heat generating electronic component is mounted thin.

The following technical scheme is proposed: in a method of heating a metal base circuit board at a temperature of 120 ℃ or higher, that is, in a state where the metal base circuit board is heated to a temperature higher by 10 ℃ or higher than the glass transition temperature (Tg) of an insulating layer, bending or pressing is performed, whereby the metal base circuit board having an uneven portion is used in combination with a case or an electronic circuit case (see patent document 4).

Further, light emitting diode light source units using light emitting diodes as light sources are used in various fields, but for example, a backlight light source of a liquid crystal display device generally uses a small fluorescent tube called CFL (cold cathode tube).

The light source of the CFL is configured such that Hg (mercury) is sealed in a discharge tube, and ultraviolet rays emitted from mercury excited by discharge are emitted to a fluorescent material on a tube wall of the CFL, and converted into visible light. Therefore, recently, in consideration of environmental aspects, it is required to use alternative light sources that do not use harmful mercury.

As a new light source, a light emitting diode (hereinafter, abbreviated as "LED") has been proposed, but the LED has directivity in light, and is used for a backlight of a planar light source system because light is obtained from one direction particularly in a type of surface mounting on a flexible substrate or the like, and therefore, unlike a conventional configuration using a CFL, light loss is also small (see patent document 5).

Backlights using LEDs as light sources have been becoming popular as backlights for liquid crystal display devices, along with cost reduction, improvement in luminous efficiency, and environmental restrictions. Meanwhile, as the liquid crystal display device has become higher in luminance and larger in display area, the number of LEDs mounted on a flexible substrate or the like has increased to increase the amount of light emission, and the output has become larger.

However, the light source of the LED has low luminous efficiency, and thus most of the input power is converted into heat and discharged when the LED emits light. When the LED is energized, heat is generated, and the generated heat causes a high temperature, and if the temperature is high, the LED is broken. In a backlight using LEDs as light sources, the generated heat is accumulated in the LEDs and a substrate on which the LEDs are mounted, and as the temperature of the LEDs increases, the light emission efficiency of the LEDs themselves decreases. Further, if the number of LEDs mounted or the input power is increased in order to increase the luminance of the backlight, the amount of heat generation increases, and it is important to remove the heat.

In order to reduce heat accumulation of an LED mounting substrate and reduce temperature rise of an LED chip, the following technical scheme is proposed: a mounting metal film for mounting an LED chip, a metal drive wiring for supplying a drive current to the LED chip, and a metal film pattern for heat dissipation are formed on an LED chip mounting surface of an LED mounting substrate, a heat dissipating metal film is formed on a surface facing the LED chip mounting surface, a metal through hole for connecting the metal pattern on one main surface side and the heat dissipating metal film on the other main surface side is formed in a thickness direction of the LED chip mounting substrate, and a metal film for dissipating heat generated from the LED to a rear surface through the metal through hole is formed (see patent document 6).

However, when the shape of the LED to be mounted is small, there are problems that the area of the metal film to be mounted is limited and the number of metal through holes formed directly below the LED is limited, and when the metal film pattern cannot be formed on the mounting substrate due to the limitation of the substrate area, there is a problem that the heat generated in the LED cannot be efficiently radiated to the back surface of the substrate.

Further, if a metal base circuit board using a metal base board having a thickness of 2mm is used instead of the flexible board, good heat dissipation can be obtained without providing a metal through hole, but there is a problem that the thickness of the board becomes large, and the die cutting size from the electrodes, the wiring pattern, and the like needs to be increased as compared with the flexible board, and the area of the board increases. In addition, since the LED mounting portion is not bent arbitrarily, the formation position of the input terminal is limited.

In addition, if the metal base of the metal base circuit board is reduced in thickness to reduce the size of the die-cut from the electrodes, the wiring pattern, and the like as in the flexible board, the metal base circuit board is slightly bent to form cracks in the insulating layer, and thus the metal base circuit board cannot be used. There is also a problem that the LED mounting portion cannot be bent arbitrarily.

Further, since the metal base circuit board can be used by bending at room temperature and has bending workability, a metal base circuit board using a metal foil of about 9 to 40 μm in which a conductor circuit is provided through an insulating layer, which is filled with a heat conductive filler, has excellent bending workability at room temperature and has heat dissipation properties, has been developed.

However, if the conductor circuit is bent at 90 ° or more with a very small radius of curvature of 0.5mm or less, the insulating layer of the bent portion may be cracked and unusable. Therefore, if the polyimide film is reinforced by a coating layer formed with an epoxy adhesive layer, the insulating layer at the bent portion can be prevented from cracking, but the bending property is lowered, and therefore, there is a problem that it is difficult to bend the polyimide film by 90 ° or more with a very small radius of curvature of 0.5mm or less.

Further, when a circuit board for mounting a semiconductor or a small-sized precision motor is mounted, there is a problem that noise is easily generated and malfunction of a module is easily caused.

Patent document 1: japanese patent laid-open No. H05-037169

Patent document 2: japanese patent laid-open No. Hei 09-139580

Patent document 3: japanese patent laid-open No. 62-271442

Patent document 4: japanese patent laid-open No. 2001-160664

Patent document 5: japanese patent laid-open No. 2005-293925

Patent document 6: japanese patent laid-open No. 2005-283852

Disclosure of The Invention

The present invention has been made to solve the problems of the prior art described above, and an object of the present invention is to provide a metal base circuit board having excellent heat dissipation properties and excellent bendability, electromagnetic wave shielding properties, and insulating properties, a method for manufacturing the same, a hybrid integrated circuit using the same, an LED module reinforced with a coating layer, and a long-life LED light source unit having high luminance and preventing damage of the LED.

That is, the main technical contents of the present invention are as follows.

(1) A metal base circuit board comprising a circuit board in which an insulating layer and a conductor circuit or a metal foil are alternately laminated, wherein the thickness of the conductor circuit or the metal foil is 5 to 450 μm, the insulating layer is formed of a cured product of a resin composition containing an inorganic filler and a thermosetting resin, and the thickness of the insulating layer is 9 to 300 μm.

(2) The metal base circuit substrate as set forth in (1), wherein at least 1 of the through holes for electrically connecting the conductor circuit or the metal foil is 0.0078mm²The above.

(3) The metal base circuit board according to the item (1) or (2), wherein the insulating layer has a thermal conductivity of 1 to 4W/mK.

(4) The metal base circuit board according to any one of (1) to (3), wherein the insulating layer has a glass transition temperature of 0 to 40 ℃.

(5) The metal base circuit board according to any one of (1) to (4), wherein the insulating layer is a cured product of a resin composition containing 25 to 60 vol% of a thermosetting resin and the balance of an inorganic filler having a sodium ion concentration of 500ppm or less, the inorganic filler being composed of coarse spherical particles having an average particle diameter of 5 to 40 μm and a maximum particle diameter of 75 μm or less and fine spherical particles having an average particle diameter of 0.3 to 3.0 μm.

(6) The metal base circuit board according to any one of (1) to (5), wherein the thermosetting resin contains a hydrogenated bisphenol F-type and/or A-type epoxy resin.

(7) The metal base circuit board according to (6), wherein the thermosetting resin contains a linear epoxy resin having an epoxy equivalent of 800 to 4000.

(8) The metal base circuit board according to (6) or (7), wherein the thermosetting resin contains a polyoxyalkylene polyamine as a curing agent.

(9) The metal base circuit board according to any one of (6) to (8), wherein the chloride ion concentration in the thermosetting resin is 500ppm or less.

(10) The metal base circuit board according to any one of (1) to (9), wherein when the circuit board is bent at an arbitrary position by 90 ° or more with a radius of curvature of 1 to 5mm, the withstand voltage between the layers of the conductor circuit or the metal foil is 1.0kV or more.

(11) The metal base circuit board according to any one of (1) to (10), wherein the metal foil is provided with the conductor circuit through the insulating layer and further provided with the coating layer having a thickness of 5 μm to 25 μm, and the gap formed by removing at least a part of the coating layer is formed in a portion where the conductor circuit is not provided.

(12) The metal base circuit board according to (11), wherein the slit is formed to have a length of 50% to 95% with respect to the bent portion.

(13) The metal base circuit board according to (11) or (12), wherein the coating layer has a thickness of 5 to 25 μm.

(14) The metal base circuit board according to any one of (11) to (13), wherein the metal base circuit board is bent at the slit portion.

(15) The metal base circuit board according to any one of (11) to (14), wherein the surface of the insulating layer is bent at 90 ° or more with a radius of curvature of 0.1 to 0.5 mm.

(16) The metal base circuit board according to any one of (11) to (15), wherein a layer having a magnetic loss or a layer having a dielectric loss is laminated on a surface of the covering layer.

(17) The metal base circuit board according to any one of (11) to (16), wherein the layer having magnetic loss is formed of a magnetic material having an aspect ratio of 2 or more and an organic binder, the content of the magnetic material is 30 to 70 vol%, and the thickness of the layer having magnetic loss is 3 to 50 μm.

(18) The metal base circuit board as described in any one of (11) to (16), wherein the layer having dielectric loss has a specific surface area of 20 to 110m²The carbon powder is 5-60 vol%, and the thickness of the layer with dielectric loss is 3-50 μm.

(19) A hybrid integrated circuit using the metal base circuit board according to any one of (1) to (10).

(20) An LED, wherein at least 1 LED is electrically connected to the metal base circuit board according to any one of (11) to (18).

(21) An LED light source unit, wherein the metal base circuit board according to any one of (1) to (18) is disposed on a surface of a case with an adhesive tape, and 1 or more light emitting diodes are mounted on a conductor circuit of the metal base circuit board.

(22) The LED light source unit of claim (21), wherein the adhesive tape has a thermal conductivity of 1 to 2W/mK and a thickness of 50 to 150 μm.

(23) The LED light source unit according to claim (21) or (22), wherein the adhesive tape contains a polymer containing acrylic acid and/or methacrylic acid.

(24) The LED light source unit according to any of claims (21) to (23), wherein the adhesive tape contains 40 to 80 vol% of a thermally conductive electrical insulating agent.

(25) The LED light source unit according to any one of claims (21) to (24), wherein the thermally conductive electrical insulating agent has a maximum particle diameter of 45 μm or less and an average particle diameter of 0.5 to 30 μm.

The metal base circuit board of the present invention has electromagnetic wave shielding properties, heat dissipation properties, and electrical insulation properties, and is bendable at room temperature, and therefore can be provided not only on a flat portion but also in close contact with a side surface or a bottom surface of a case, a staggered layer, a curved surface, or the like. Further, since the electronic component can be easily bent at room temperature in a state where the electronic component such as a semiconductor element or an impedance chip which requires heat dissipation is mounted, it is possible to realize miniaturization and thinning of an electronic device in which a high heat generating electronic component is mounted, which have been difficult in the past.

In addition, since the heat emitted from the LED light source can be dissipated to the back surface side of the substrate and dissipated to the outside through the heat conductive adhesive tape, the heat accumulation of the LED mounting substrate can be reduced, and the temperature rise of the LED can be reduced. Therefore, it is possible to provide an LED light source unit having high luminance and a long life by suppressing a decrease in the light emission efficiency of the LED and preventing damage to the LED.

Brief description of the drawings

FIG. 1-1 is a schematic view showing an example of a hybrid integrated circuit using a metal base circuit board according to the present invention.

FIG. 2-1 is a plan view of an example of the metal base circuit board of the present invention.

FIG. 2-2 is a plan view showing an example of the metal base circuit board of the present invention (a coating layer is disposed on the surface of FIG. 2-1).

Fig. 2 to 3 are plan views showing examples of the metal base circuit board of the present invention (in which a layer having a magnetic loss or a layer having a dielectric loss is disposed on the surface of fig. 2 to 2).

Fig. 2 to 4 are plan views showing an example of the metal base circuit board (heat dissipation member is disposed on the surface of fig. 2 to 3) according to the present invention.

Fig. 2-5 are cross-sectional views of another metal-based circuit substrate of the present invention.

Fig. 2-6 are plan views of another metal-based circuit substrate of the present invention.

Fig. 2-7 are plan views of another metal-based circuit substrate of the present invention.

FIG. 3-1 is a cross-sectional view of an example of the LED light source unit of the present invention.

Description of the symbols

1: metal foil, 2: insulating layer, 3: conductor circuit, 4: a heat sink, 5: output semiconductor, 6: control semiconductor, 7: bonding wire, 8: chip component, 9: soldered portion, 10: thermally conductive adhesive, 11: case having heat radiation, 21: metal foil, 22: insulating layer, 23: conductor circuit, 24: electrode, 25: gap portion, 26: coating layer, 26 a: epoxy adhesive layer, 27: component mounting section, 28: input terminal, 29 a: layer with magnetic loss, 29 b: layer with dielectric loss, 210: heat generating component (LED), 211: bending position, 212: cartridge, 213: thermal conductive adhesive tape, 31: metal foil, 32: insulating layer, 33: conductor circuit, 34: input circuit (lead-out wiring), 35: soldered portion, 36: LED, 37: thermally conductive adhesive tape, 38: and (5) a box body.

Best Mode for Carrying Out The Invention

Preferred embodiments of the metal base circuit board, the hybrid integrated circuit, the LED module, and the LED light source unit according to the present invention are as follows.

(1-1) A metal base circuit board comprising a metal foil and a conductor circuit provided on the metal foil with an insulating layer interposed therebetween, wherein the metal foil has a thickness of 5 to 300 μm, the insulating layer containing an inorganic filler and a thermosetting resin has a thickness of 80 to 200 μm, and the conductor circuit has a thickness of 9 to 140 μm.

(1-2) the metal base circuit board according to (1-1), wherein the thermosetting resin contains a hydrogenated bisphenol F-type and/or A-type epoxy resin.

(1-3) the metal base circuit board according to (1-2), wherein the thermosetting resin contains a linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000.

(1-4) the metal base circuit board according to any one of (1-1) to (1-3), wherein the chloride ion concentration in the thermosetting resin is 500ppm or less.

(1-5) the metal base circuit board according to any one of (1-1) to (1-4), wherein the insulating layer has a glass transition temperature of 0 to 40 ℃.

(1-6) the metal base circuit board according to any one of (1-1) to (1-5), wherein the insulating layer contains 25 to 50 vol% of the thermosetting resin, and the balance is an inorganic filler having a sodium ion concentration of 500ppm or less, the inorganic filler being composed of coarse spherical particles having an average particle diameter of 10 to 40 μm and a maximum particle diameter of 75 μm or less, and fine spherical particles having an average particle diameter of 0.4 to 1.2 μm.

(1-7) the metal base circuit board according to any one of (1-1) to (1-6), wherein the metal base circuit board is bent toward the conductor circuit side or the opposite side to the conductor circuit.

(1-8) the metal base circuit board according to any one of (1-1) to (1-6), wherein the metal base circuit board is bent at 90 ° or more to the side of the conductor circuit or the side opposite to the conductor circuit with a radius of curvature of 1 to 5 mm.

(1-9) the metal-based circuit board according to any one of (1-1) to (1-6), wherein the insulating layer has a thermal conductivity of 1 to 4W/mK, and wherein a withstand voltage between the conductor circuit and the metal foil is 1.5kV or more in a state of being bent at 90 ° or more with a radius of curvature of 1 to 5 mm.

(1-10) the method for manufacturing a metal base circuit board according to any one of (1-7) to (1-9), wherein the bending is performed at room temperature.

(1-11) A hybrid integrated circuit using the metal base circuit board according to any one of (1-1) to (1-9).

(2-1) A circuit board comprising an insulating layer and a conductor circuit or a metal foil laminated alternately, wherein the conductor circuit or the metal foil has a thickness of 5 to 450 μm, the insulating layer is formed of a cured product of a resin composition containing an inorganic filler and a thermosetting resin, and the insulating layer has a thickness of 9 to 300 μm.

(2-2) the circuit substrate as described in (2-1), wherein at least 1 of the through holes for electrically connecting the conductor circuit or the metal foil is 0.0078mm²The above.

(2-3) the circuit board according to (2-1) or (2-2), wherein the insulating layer has a thermal conductivity of 1 to 4W/mK.

(2-4) the circuit board according to any one of (2-1) to (2-3), wherein the insulating layer has a glass transition temperature of 0 to 40 ℃.

(2-5) the circuit board according to any one of (2-1) to (2-4), wherein the insulating layer is a cured product of a resin composition containing 25 to 60 vol% of a thermosetting resin and the balance of an inorganic filler comprising coarse spherical particles having an average particle diameter of 5 to 40 μm and a maximum particle diameter of 75 μm or less and fine spherical particles having an average particle diameter of 0.3 to 3.0 μm.

(2-6) the circuit board according to any one of (2-1) to (2-5), wherein when the circuit board is bent at an arbitrary position by 90 ° or more with a radius of curvature of 1 to 5mm, a withstand voltage between the layers of the conductor circuit or the metal foil is 1.0kV or more.

(3-1) A metal base circuit board comprising a metal foil and a conductor circuit provided thereon via an insulating layer and a coating layer provided thereon, wherein a slit formed by removing at least a part of the coating layer is formed in a portion where the conductor circuit is not provided.

(3-2) the metal base circuit board according to (3-1), wherein the slit is formed to have a length of 50% to 95% with respect to the bent portion.

(3-3) the metal base circuit board according to (3-1) or (3-2), wherein the insulating layer is formed of a thermosetting resin containing an inorganic filler, the insulating layer has a thickness of 30 to 80 μm, the metal foil has a thickness of 5 to 40 μm, and the conductor circuit has a thickness of 9 to 40 μm.

(3-4) the metal base circuit board according to any one of (3-1) to (3-3), wherein the insulating layer is formed of an inorganic filler having a sodium ion concentration of 500ppm or less, which is 50 to 75% by volume of spherical particles having an average particle diameter of 30 μm or less and a maximum particle diameter of 2 to 15 μm, and the balance of a thermosetting resin.

(3-5) the metal base circuit board according to any one of (3-1) to (3-4), wherein the thermosetting resin contains a hydrogenated bisphenol F-type and/or A-type epoxy resin.

(3-6) the metal-based circuit board according to any one of (3-1) to (3-5), wherein the thermosetting resin contains a linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000.

(3-7) the metal-based circuit board according to any one of (3-1) to (3-6), wherein the chloride ion concentration in the thermosetting resin is 500ppm or less.

(3-8) the metal base circuit board according to any one of (3-1) to (3-7), wherein the insulating layer has a glass transition temperature of 0 to 40 ℃.

(3-9) the metal base circuit board according to any one of (3-1) to (3-8), wherein the coating layer has a thickness of 5 to 25 μm.

(3-10) the metal base circuit board according to any one of (3-1) to (3-9), wherein the metal base circuit board is bent at the slit portion.

(3-11) the metal base circuit board according to any one of (3-1) to (3-10), wherein the surface of the insulating layer is bent at 90 ° or more with a radius of curvature of 0.1 to 0.5 mm.

(3-12) the metal base circuit board according to any one of (3-1) to (3-11), wherein a layer having a magnetic loss or a layer having a dielectric loss is laminated on a surface of the covering layer.

(3-13) the metal base circuit board according to (3-12), wherein the layer having magnetic loss is formed of a magnetic material having an aspect ratio of 2 or more and an organic binder, the content of the magnetic material is 30 to 70 vol%, and the thickness of the layer having magnetic loss is 3 to 50 μm.

(3-14) the metal base circuit board according to (3-12), wherein the layer having dielectric loss has a specific surface area of 20 to 110m²(ii) carbon powder in an amount of 5 to c,/g, and an organic binder60% by volume, the layer having dielectric loss has a thickness of 3 μm to 50 μm.

(3-15) the metal base circuit board according to (3-14), wherein the carbon powder is carbon black having a boron solid solution with a volume resistivity of 0.1. omega. cm or less according to JIS K1469.

(3-16) the metal-based circuit board according to any one of (3-1) to (3-15), wherein the insulating layer has a thermal conductivity of 1 to 4W/mK, and a withstand voltage between the conductor circuit and the metal foil is 1.0kV or more.

(3-17) an LED, wherein at least 1 LED is electrically connected to the conductor circuit of the metal base circuit board according to any one of (3-1) to (3-16).

(4-1) an LED light source unit comprising a metal base circuit board having a conductor circuit formed on a metal foil with an insulating layer interposed therebetween, the metal base circuit board being disposed on a surface of a case via an adhesive tape, and 1 or more light emitting diodes being mounted on the conductor circuit of the metal base circuit board, wherein the metal foil has a thickness of 18 to 300 μm, the insulating layer contains an inorganic filler and a thermosetting resin and has a thickness of 80 to 200 μm, and the conductor circuit has a thickness of 9 to 140 μm.

(4-2) the LED light source unit according to (4-1), wherein the insulating layer has a thermal conductivity of 1 to 4W/mK.

(4-3) the LED light source unit according to (4-1) or (4-2), wherein the insulating layer contains 25 to 50 vol% of the thermosetting resin, and the remainder is an inorganic filler composed of coarse spherical particles having an average particle diameter of not more than 75 μm and not more than 10 to 40 μm and fine spherical particles having an average particle diameter of 0.4 to 1.2 μm.

(4-4) the LED light source unit according to any one of (4-1) to (4-3), wherein the glass transition temperature of the thermosetting resin in the insulating layer is 0 to 40 ℃.

(4-5) the LED light source unit according to any one of (4-1) to (4-4), wherein the thermosetting resin contains a hydrogenated bisphenol F-type and/or A-type epoxy resin.

(4-6) the LED light source unit according to any one of (4-1) to (4-5), wherein the thermosetting resin contains a linear epoxy resin having an epoxy equivalent of 800 to 4000.

(4-7) the LED light source unit according to any one of (4-1) to (4-6), wherein the thermosetting resin contains a polyoxyalkylene polyamine.

(4-8) the LED light source unit according to any one of (4-1) to (4-7), wherein the polyoxyalkylene polyamine is contained under a condition that the active hydrogen equivalent is 0.8 to 1 times the epoxy equivalent of the epoxy resin contained in the thermosetting resin.

(4-9) the LED light source unit according to any one of (4-1) to (4-8), wherein the metal-based circuit board is bent at a radius of curvature of 1 to 5mm at a portion of 1 or more other than a portion where the LED is mounted, by 90 ° or more to the conductor circuit surface or a portion opposite to the conductor circuit surface, and a withstand voltage between the conductor circuit and the metal foil of the bent metal-based circuit board is 1.5kV or more.

(4-10) the LED light source unit according to any one of (4-1) to (4-9), wherein the adhesive tape has a thermal conductivity of 1 to 2W/mK and a thickness of 50 to 150 μm.

(4-11) the LED light source unit according to any one of (4-1) to (4-10), wherein the adhesive tape contains a polymer containing acrylic acid and/or methacrylic acid.

(4-12) the LED light source unit according to any one of (4-1) to (4-11), wherein the adhesive tape contains 40 to 80 vol% of a thermally conductive electrical insulating agent.

(4-13) the LED light source unit according to any one of (4-1) to (4-12), wherein the thermally conductive electrical insulating agent is an acrylic rubber.

(4-14) the LED light source unit according to any one of (4-1) to (4-13), wherein the polymer is an acrylic polymer obtained by polymerizing a monomer including a (meth) acrylate monomer.

(4-15) the LED light source unit according to any one of (4-1) to (4-14), wherein the (meth) acrylate monomer is 2-ethylhexyl acrylate.

(4-16) the LED light source unit according to any one of (4-1) to (4-15), wherein the thermally conductive electrical insulating agent has a maximum particle diameter of 45 μm or less and an average particle diameter of 0.5 to 30 μm.

(4-17) the LED light source unit according to any one of (4-1) to (4-16), wherein the thermally conductive electrical insulating agent is at least one selected from the group consisting of alumina, crystalline silica and aluminum hydroxide.

Hereinafter, preferred embodiments for carrying out the present invention will be described in detail.

The following structure of the metal base circuit board and metal foil, inorganic filler, thermosetting resin, conductor circuit, and the like, which are main constituent materials, are suitable for hybrid integrated circuits, LED modules, and LED light source units.

< Metal base Circuit Board >

The structure of the metal base circuit board, which is the base of the present invention, and the characteristics of the constituent materials, and the like, will be described.

The circuit board of the present invention is a circuit board in which an insulating layer and a conductor circuit or a metal foil are alternately laminated, wherein the thickness of the conductor circuit or the metal foil is 5 to 450 μm, the insulating layer is formed of a cured product of a resin composition containing an inorganic filler and a thermosetting resin, and the thickness of the insulating layer is 9 to 300 μm.

This is because, when the thickness of the conductor circuit or the metal foil is 5 μm or less, the conductor circuit or the metal foil cannot be manufactured due to problems such as handling, and when the thickness is 450 μm or more, not only the bendability is lowered but also the entire circuit board becomes thick.

In the present invention, the metal base circuit board can be used by being bent at room temperature, and can be used even by being repeatedly bent, so that the metal base circuit board has high workability and can be reused.

[ Metal foil ]

As the material of the metal foil, aluminum or an aluminum alloy, copper or a copper alloy, iron, stainless steel, or the like can be used. Further, depending on the material of the metal foil, it is preferable to perform surface treatment such as electrolytic treatment, etching treatment, plasma treatment, undercoating treatment, or coupling treatment on the insulating layer side of the metal foil in order to improve adhesiveness.

[ insulating layer ]

In the invention, the thermal conductivity of the insulating layer is preferably 1-4W/mK, more preferably 2-3W/mK. If the thermal conductivity is less than 1W/mK, the thermal resistance of the circuit board is high, and the desired heat dissipation may not be obtained. In addition, in order to obtain a thermal conductivity of 4W/mK or more, the amount of the inorganic filler needs to be increased, and thus flexibility is lost, and good bending performance may not be obtained.

In addition, the glass transition temperature of the insulating layer is preferably 0 to 40 ℃, more preferably 10 to 30 ℃. If the glass transition temperature is less than 0 ℃, the rigidity and electrical insulation properties are low, and if it exceeds 40 ℃, the bendability is low. When the glass transition temperature is 0 to 40 ℃, it is not so hard at room temperature as an insulating layer used in a conventional metal base substrate, and a drop in withstand voltage due to peeling from a metal foil or cracking of the insulating layer is unlikely to occur even when bending or extrusion is performed at room temperature.

The thickness of the insulating layer is preferably 9 μm to 300. mu.m.

In the present invention, the insulating layer is a cured product of a resin composition containing 25 to 60 vol% of a thermosetting resin and the balance of an inorganic filler composed of coarse spherical particles having an average particle diameter of 5 to 40 μm and a maximum particle diameter of 75 μm or less and fine spherical particles having an average particle diameter of 0.3 to 3.0 μm. If the content of the thermosetting resin is not less than the above volume%, heat dissipation is reduced, and the above thermal conductivity cannot be obtained.

The thermosetting resin constituting the insulating layer may be a resin mainly composed of a linear high molecular epoxy resin having an epoxy equivalent of 800 to 4000 and a hydrogenated bisphenol F-type and/or A-type epoxy resin, and a phenol resin, a polyimide resin, a phenoxy resin, an acrylic rubber, an acrylonitrile-butadiene rubber, or the like may be further blended, and if flexibility at room temperature, electrical insulation properties, heat resistance, or the like is taken into consideration, the blending amount thereof is preferably 30% by mass or less based on the total amount with the epoxy resin.

As the thermosetting resin constituting the insulating layer, an epoxy resin, a phenol resin, a silicone resin, an acrylic resin, or the like can be used. Among them, a material containing an inorganic filler, an epoxy resin and an addition polymerization type epoxy curing agent as main components, which has good adhesion between the metal foil 1 and the conductor circuit in a cured state and good bendability at room temperature, is preferable.

The addition polymerization type epoxy curing agent is preferably a polyoxyalkylene polyamine having an effect of improving the flexibility of the thermosetting resin after thermosetting, and is preferably added under a condition that the active hydrogen equivalent is 0.8 to 1 times the epoxy equivalent of the epoxy resin contained in the thermosetting resin in order to secure the rigidity, bending workability, insulation property, and the like of the insulating layer.

The thermosetting resin constituting the insulating layer is preferably a hydrogenated bisphenol F-type and/or A-type epoxy resin, and if the epoxy equivalent is 180 to 240, the resin is liquid at room temperature, and can be used in the range of 60 to 100 mass% in the thermosetting resin. The hydrogenated bisphenol F-type and/or A-type epoxy resin is not a rigid structure as compared with the conventional bisphenol F-type and A-type epoxy resins, and therefore has good flexibility as a curable resin composition. Further, since the viscosity of the resin is low, 0 to 40 mass% of a linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000 may be added to the thermosetting resin, and 50 to 75 volume% of an inorganic filler may be added to the insulating layer.

When the epoxy equivalent of the hydrogenated bisphenol F-type and/or a-type epoxy resin is less than 180, the amount of low-molecular-weight impurities having epoxy groups remaining in the purification process of the epoxy resin is large, and the adhesive strength and the insulating property are undesirably lowered. Further, if the epoxy equivalent exceeds 240, the resin viscosity is high, and the resin viscosity is further increased by the addition of the linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000, and it is difficult to add 0 to 40% by mass of the high molecular weight epoxy resin to the thermosetting resin, and 50 to 75% by volume of the inorganic filler may be added to the insulating layer.

When a linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000 is contained in the insulating layer, the adhesion is improved as compared with a case where only a linear epoxy resin having an epoxy equivalent of less than 800 is used as the thermosetting resin. Further, it is more preferable to use a hydrogenated bisphenol F-type and/or A-type epoxy resin as the linear high molecular weight epoxy resin having an epoxy equivalent of 800 to 4000 because not only the adhesiveness but also the bendability at room temperature are improved.

Further, if a linear high molecular weight epoxy resin having an epoxy equivalent of more than 4000 is contained in the insulating layer, it is difficult to fill the inorganic filler and to dissolve it in other epoxy resins, and the insulating layer is formed in a state where the epoxy resin, the epoxy curing agent, the inorganic filler, and other components contained therein are not uniform, and thus heat dissipation and electrical insulation properties are deteriorated. The linear epoxy resin having an epoxy equivalent of 800 to 4000 is preferably added to the curable resin in an amount of 40% by mass or less, and if it exceeds 40% by mass, the amount of the epoxy curing agent added is reduced, the glass transition temperature (Tg) of the thermosetting resin is increased, and the flexibility may be lowered.

The chloride ion concentration in the thermosetting resin constituting the insulating layer is preferably 500ppm or less, more preferably 250ppm or less. In a conventional metal base circuit board, if the chloride ion concentration in the thermosetting resin constituting the insulating layer is 1000ppm or less, the electrical insulating property is good even at high temperatures and direct current voltages. However, the curable resin composition constituting the insulating layer used for the metal base circuit board of the present invention has a flexible structure that can be bent even at room temperature, and if the chloride ion concentration in the curable resin composition exceeds 500ppm, ionic impurities are moved at high temperature and direct current voltage, and the electrical insulation properties tend to be lowered.

The inorganic filler contained in the insulating layer is preferably a material having electrical insulation and good thermal conductivity, and examples thereof include silicon oxide, aluminum nitride, silicon nitride, and boron nitride. The particle size of the inorganic filler is preferably a coarse spherical particle having an average particle size of 5 to 40 μm and a fine spherical particle having an average particle size of 0.3 to 3.0 μm, wherein the maximum particle size is 75 μm or less. In this range, it is more preferable to contain spherical coarse particles having an average particle size of 10 to 40 μm and spherical fine particles having an average particle size of 0.4 to 1.2 μm. Further, if the spherical coarse particles and the spherical fine particles are mixed, the filling density can be increased as compared with the case of using the crushed particles or the spherical particles alone, and the bendability at room temperature is improved.

The content of the inorganic filler in the insulating layer is preferably 50 to 75% by volume, more preferably 55 to 65% by volume.

The sodium ion concentration in the inorganic filler is preferably 500ppm or less, more preferably 100ppm or less. If the sodium ion concentration in the inorganic filler exceeds 500ppm, the ionic impurities are moved at a high temperature and a direct current voltage, and the electrical insulation property tends to be lowered.

In the present invention, it is more preferable that at least 1 of the through holes for electrically connecting the conductor circuits or the metal foils is 0.0078mm²The above. The conductive circuit, the metal foil, and the insulating layer are chemically, physically, or mechanically removed to form a hole for a through hole, and the through hole is electrically connected by filling a conductive material or the like in the space by plating, printing, or the like, or by wire bonding from the upper conductive circuit. The through-hole may be formed or may not be formed.

[ conductor circuit ]

In the present invention, it is preferable that the circuit board is bent at an arbitrary position by 90 ° or more with a radius of curvature of 1 to 5mm, and the withstand voltage between the layers of the conductor circuit or the metal foil is 1.0kV or more. If the sheet is bent at a radius of curvature of 1mm or less by 90 ° or more, the withstand voltage between the layers of the conductor circuit or the metal foil may be 1.0kV or less due to cracking of the insulating layer or the like. When the radius of curvature is 5mm or more or 90 ° or less, the intended module may not be miniaturized.

The thickness of the conductor circuit is preferably 9 μm to 140 μm, and when it is less than 9 μm, the function as a conductor circuit is insufficient, and when it exceeds 140 μm, not only the flexibility is lowered, but also the thickness is increased, and it is difficult to reduce the size and thin the circuit.

< hybrid Integrated Circuit >

Hereinafter, a preferred embodiment of a hybrid integrated circuit using the metal base circuit board of the present invention will be described. As a hybrid integrated circuit using the metal base circuit board of the present invention, a metal foil, an inorganic filler, a thermosetting resin, a conductor circuit, and the like, which are main constituent materials of the metal base circuit board described above, can be suitably used.

Fig. 1-1 shows an example of a metal base circuit board and a hybrid integrated circuit using the same according to the present invention.

In the hybrid integrated circuit of the present invention, a plurality of semiconductors, i.e., an output semiconductor 5, a control semiconductor 6, and a chip component 8, are mounted on a conductor circuit 3 of a metal base circuit board including a metal foil 1, an insulating layer 2, and the conductor circuit 3 by bonding via a soldering portion 9 or the like, and are adhered to a case 11 having heat radiation properties via a thermally conductive adhesive 10. The output semiconductor 5 is usually connected to the conductor circuit 3 through a heat sink 4 to promote heat dissipation, but may not be used.

Since the control semiconductor 6 is not usually accompanied by large heat generation, it is not bonded to the conductor circuit 3 via a heat sink, but may be bonded via a heat sink.

As the thermally conductive adhesive, an adhesive obtained by filling a highly thermally conductive filler such as gold, silver, nickel, aluminum nitride, aluminum, or aluminum oxide with an epoxy resin, a urethane resin, a silicone resin, or the like can be used. A thermally conductive adhesive sheet formed in a sheet shape in advance may be used instead of the thermally conductive adhesive.

Further, it may be fixed by adhesion of silicone grease, fixing by screw fixation, or the like, as long as the metal base circuit board and the case 11 having heat dissipation properties are fixed by a good heat conduction between the metal base circuit board and the case 11 having heat dissipation properties. The heat conductive adhesive is used for promoting heat dissipation of the output semiconductor 5 and protection and fixation of the hybrid integrated circuit, but may not be used.

A signal from the control semiconductor 6 is electrically connected to the output semiconductor 5 via the conductor circuit 3 and the bonding wire 7. The metal foil 1, the insulating layer 2, and the conductor circuit 3 constituting the metal base circuit board except for the portion where the output semiconductor 5, the control semiconductor 6, and the chip component 8 are mounted may be subjected to bending or extrusion at room temperature in accordance with the shape of the heat sink or the case 11 having heat dissipation properties. Further, the heat sink may be provided not only in a flat portion but also in a side surface or a bottom surface of the case, a staggered layer, a curved surface, or the like, depending on the shape of the heat sink or the case having heat radiation properties. Therefore, it is possible to reduce the size and thickness of a high heat generating hybrid integrated circuit that cannot be applied to a conventional metal base circuit board and a conventional flexible wiring board.

The hybrid integrated circuit using the metal-based circuit board of the present invention has the above-described structure, and has the same characteristics as a conventional metal-based circuit board having a flat metal plate, in that the insulating layer has a thermal conductivity of 1 to 4W/mK, and the withstand voltage between the conductor circuit and the metal foil is 1.5kV or more. In addition, the present invention can be applied not only to a flat portion but also to a side surface or a bottom surface of the case, a staggered layer, a curved surface, or the like. In addition, even in a state where an electric component such as a semiconductor element or an impedance chip which requires heat dissipation is mounted, it is possible to easily bend at room temperature, and therefore, it is possible to eliminate the conventional limitation that only a metal base circuit board can be used for a flat portion.

The thickness of the metal foil 1 to be used is 5 μm to 450 μm, and is preferably 35 μm to 70 μm because rigidity, bending workability, extrusion workability, and the like of the metal base circuit board can be secured.

The thickness of the insulating layer 2 is preferably 80 μm to 200 μm, and when it is less than 80 μm, the insulating property is low, and when it exceeds 200 μm, not only the heat dissipation property is lowered, but also the thickness is increased, and it is difficult to make the size and thickness small.

< LED Module >

Hereinafter, a preferred embodiment of an LED module (hereinafter, also simply referred to as an "LED array") having a coating layer on a surface of a metal base circuit board will be described. As the LED array using the metal base circuit board of the present invention, metal foil, inorganic filler, thermosetting resin, conductor circuit, and the like, which are main constituent materials in the metal base circuit board described above, can be suitably used.

Fig. 2-1 to 2-7 are plan views showing the general structure of an example of the metal base circuit board of the present invention and an LED module using the same.

In the LED module using the metal base circuit board of the present invention, in the metal base circuit board including the metal foil 21, the insulating layer 22, the conductor circuit 23, and the electrode 24, the metal foil 21 and the insulating layer 22 are partially removed at positions where the conductor circuit 23 and the electrode 24 are not formed, and the slit portion 25 is formed.

In fig. 2-2, the metal base circuit board of fig. 2-1 is reinforced by attaching the coating layer 26 on the side where the conductor circuit 23 and the electrode 24 are formed, excluding the component mounting portion 27 and the input terminal 28. Here, the coating layer 26 is partially removed at a position where the conductor circuit 23 and the electrode 24 are not formed, and the slit portion 25 is formed, similarly to the metal foil 21 and the insulating layer 22. The slit 25 of the coating layer 26 is preferably processed to have a length of 50% to 95% with respect to the bent portion. If the length of the bent portion is 50% or more, the bent portion can be bent at a radius of curvature of 0.5mm or less by 90 °, and if the bent portion is processed to 95% or less, the reinforcing effect of the coating layer is not exerted at the bent portion, and there is no problem such as disconnection of the conductor circuit at the bent portion or generation of cracks in the insulating layer. The thickness of the coating layer is preferably 5 to 25 μm.

In fig. 2-3, a layer 29a having magnetic loss or a layer 29b having dielectric loss is formed on the metal base circuit board of fig. 2-2 above the coating layer 26.

The layer 29a having magnetic loss is formed of a magnetic material having an aspect ratio of 2 or more and an organic binder, and exhibits good magnetic loss characteristics when the content of the magnetic material is 30 to 70 vol% and the thickness of the layer is 3 to 50 μm.

In addition, in the case of forming the layer 29b having dielectric loss in the metal base circuit board of FIGS. 2 to 3, if the layer 29b having dielectric loss is formed of a material having a specific surface area of 20 to 110m²The carbon powder is 5-60 vol% and the thickness is 3-50 μm, so that the carbon powder has good dielectric loss characteristics.

The carbon powder of the layer having dielectric loss is preferably carbon black having a boron solid solution with a volume resistivity of 0.1. omega. cm or less in accordance with JIS K1469 because it can exhibit good dielectric loss characteristics.

In fig. 2 to 4, the heat generating component 210 is mounted on the component mounting portion of the metal base circuit board of the present invention. Here, the broken lines shown in fig. 2 to 4 indicate the bending positions 211 of the metal base circuit substrate of the present invention.

Since the slit portion 25 is formed at the bending position 211, the conductor circuit at the bending position can be easily bent, and even if the conductor circuit is bent, the conductor circuit is reinforced by the coating layer 26, so that disconnection does not occur and the insulating layer does not crack.

Thus, the metal base circuit board of the present invention has a great advantage that the metal base circuit board can prevent the problems of disconnection of the conductor circuit and cracking of the insulating layer even when bent by the coating layer reinforcing board, and can be bent well by the slit processing. Further, by forming a layer having magnetic loss or a layer having dielectric loss, a metal base circuit board having excellent electromagnetic wave absorption characteristics can be obtained.

Conventionally, when a metal base circuit board having a board thickness of about 150 μm is bent at 90 ° or more with a radius of curvature of 0.5mm or less, problems such as disconnection of a conductor circuit and cracking of an insulating layer occur, and it is necessary to reinforce the metal base circuit board with a coating layer. However, if the metal base circuit board is reinforced by the coating layer, the metal base circuit board becomes rigid and is difficult to bend at a desired position.

The present invention provides an epoch-making metal base circuit board which simultaneously achieves reinforcement and bendability of a substrate to be bent and has electromagnetic wave absorption characteristics.

Fig. 2 to 5 are schematic configurations of an example of the metal base circuit board of the present invention and an LED module using the same, and are cross-sectional views of the metal base circuit board of fig. 2 to 4 in which an input circuit is bent by 180 ° at a slit portion. In the metal base circuit board of the present invention, a coating layer 26 is formed on a metal base circuit board comprising a metal foil 21, an insulating layer 22, a conductor circuit 23 and an electrode 24 via an adhesive layer, and a layer 29a having a magnetic loss or a layer 29b having a dielectric loss is formed thereon.

In the metal base circuit board of fig. 25, the conductor circuit 23 and the electrode 24 are electrically connected, and the heat generating component 210 is mounted on the electrode 24 by electrical connection such as soldering. The back surface of the metal base circuit board is closely attached to the case 212 having heat radiation property via a heat conductive adhesive tape 213. The conductor circuit 23 is electrically connected to a lead line (input circuit) and is in a state where power can be input from the outside to a heat generating component such as an LED.

In fig. 2 to 5, the metal foil 21 is bent, but in the present invention, the metal foil may be easily bent toward the layer 29a having a magnetic loss or the layer 29b having a dielectric loss. If the coating layer at least at the portion to be bent is slit processed to have a length of 50% to 95% with respect to the bent portion, the coating layer can be bent in various shapes according to the shape of case 212 having heat radiation properties.

The above-described slit processing may be performed not only in a rectangular shape as shown in fig. 2-1 to 2-4, but also in a shape in which the corners are acute angles as shown in fig. 2-6, a wedge shape, a shape in which a plurality of circles are formed as shown in fig. 2-7, or the like. Of course, since the bent portion is easily determined, a round shape is preferable.

The LED array using the metal base circuit board of the present invention preferably has the structure described above, the metal foil 21 has a thickness of 5 μm to 40 μm, the insulating layer 22 contains an inorganic filler and a thermosetting resin and has a thickness of 30 μm to 80 μm, and the conductor circuit has a thickness of 9 μm to 40 μm. When these conditions are satisfied, the object of the present invention can be achieved more reliably.

If the thickness of the metal foil 21 is 5 μm or more, the rigidity of the metal base circuit board is not lowered, and the use is not limited. If the thickness of the metal foil 21 is 40 μm or less, processing equipment such as a bending die, an extrusion die, and a press for the metal base circuit board is not necessary, and it is not difficult to closely adhere the metal base circuit board to the curved surface of the case. In addition, it is not difficult to bend at room temperature in a state where an electric component such as a semiconductor element or an impedance chip, which requires heat dissipation, is mounted on the metal base circuit board. The metal base circuit board is excellent in rigidity, bending workability, extrusion workability, etc., particularly in bending workability with a curvature radius of 0.1 to 0.5mm and 90 ° or more, and therefore the thickness of the metal foil 21 is more preferably 12 to 35 μm.

In the LED array using the metal base circuit board of the present invention, the insulating layer 22 preferably contains an inorganic filler and a thermosetting resin and has a thickness of 30 μm to 80 μm. The thickness of the insulating layer 22 is 30 μm or more, which ensures insulation, and 80 μm or less, which does not deteriorate the bending workability of 90 ° or more with a curvature radius of 0.1 to 0.5 mm.

In the LED array using the metal base circuit board of the present invention, the thickness of the conductor circuit is preferably 9 to 40 μm. When the thickness is 9 μm or more, the function as a conductor circuit can be sufficiently ensured, and when the thickness is 40 μm, sufficient flexibility can be ensured, and a thickness sufficient for miniaturization and thinning can be ensured.

The thermally conductive adhesive tape 213 used in the present invention may be one obtained by filling a polymer resin material with a thermally conductive electrical insulating agent made of a metal oxide such as alumina or titania, a nitride such as aluminum nitride, boron nitride, or silicon nitride, an inorganic material such as silicon carbide or aluminum hydroxide, or an organic material such as acrylic rubber, or may be one obtained by filling a polymer resin material with a material surface-treated with a silane coupling agent or the like.

In order to efficiently dissipate heat generated from the heat generating component from the back surface of the metal base circuit board to the case through the metal base circuit board, the heat conductive adhesive tape 213 is preferably an adhesive tape having a higher heat conductivity than conventional adhesive tapes.

As the thermally conductive adhesive tape 213, an adhesive tape having the material and characteristics used in the following < LED light source unit > can be suitably used.

< LED light Source Unit >

A preferred embodiment of an LED light source unit using the metal base circuit board of the present invention will be described. As the LED light source unit using the metal base circuit board of the present invention, a metal foil, an inorganic filler, a thermosetting resin, a conductor circuit, and the like, which are main constituent materials in the metal base circuit board described above, can be suitably used.

Fig. 3-1 is a cross-sectional view showing a schematic configuration of an example of the LED light source unit of the present invention.

In the LED light source unit of the present invention, 1 or more LEDs 36 are mounted on the conductor circuit 33 of the metal base circuit board composed of the metal foil 31, the insulating layer 32, and the conductor circuit 33 by being joined by the soldering portion 35 or the like, and are adhered to the case 38 having heat radiation property via the heat conductive adhesive tape 37. The conductor circuit 33 and the lead line (input circuit) 34 are electrically connected to each other, and are in a state where power can be input to the LED from the outside.

In addition, although the overall shape of fig. 3-1 is box-shaped, in the present invention, the metal foil 31, the insulating layer 32, and the conductor circuit 33 constituting the metal base circuit board other than the portion where the LED36 is mounted may be in close contact with the case 38 having heat radiation properties, and various shapes may be adopted depending on the surface shape of the case 38 having heat radiation properties.

The LED light source unit of the present invention preferably has the above-described structure, wherein the metal foil 31 has a thickness of 18 to 300 μm, the insulating layer 32 contains an inorganic filler and a thermosetting resin and has a thickness of 80 to 200 μm, and the conductor circuit 33 has a thickness of 9 to 140 μm.

The thickness of the metal foil 31 is preferably 18 μm to 300. mu.m. When the thickness of the metal foil 31 is less than 18 μm, the rigidity of the metal base circuit board is lowered, and the use is limited. If the thickness exceeds 300. mu.m, not only a bending die, an extrusion die, a press or other processing equipment for the metal base circuit board is required, but it is difficult to closely bond the metal base circuit board to the curved surface of the case. In addition, it is difficult to bend the metal base circuit board at room temperature in a state where an electric component such as a semiconductor element or an impedance chip, which requires heat dissipation, is mounted on the metal base circuit board. The metal base circuit board is preferably 35 to 70 μm in rigidity, bendability, extrudability, and the like, particularly, since the metal base circuit board has good bending workability with a curvature radius of 1 to 5mm and 90 ° or more.

The insulating layer 32 preferably contains an inorganic filler and a thermosetting resin and has a thickness of 80 to 200 μm. With respect to the thickness of the insulating layer 32, if it is less than 80 μm, the insulation property is low, and if it exceeds 200 μm, not only the heat dissipation property is lowered, but also the thickness is increased, and it is difficult to make the size and thickness small.

In the LED light source unit of the present invention, the thickness of the conductor circuit is preferably 9 to 140 μm. If the thickness is less than 9 μm, the function as a conductor circuit is insufficient, and if the thickness exceeds 140 μm, not only the flexibility is lowered, but also the thickness is increased, and it is difficult to reduce the size and the thickness.

The LED light source unit of the present invention can be used even when repeatedly bent, and therefore, has high workability and can be reused. Further, the LED light source unit having the case with the curved surface can be easily produced by mounting the LED on the metal base circuit board, bonding the LED to the case with the flat surface portion, and then processing and deforming the LED together with the case.

As the thermally conductive adhesive tape 37 used in the present invention, a thermally conductive adhesive tape obtained by filling a polymer resin material with a thermally conductive electrical insulating agent made of a metal oxide such as alumina or titania, a nitride such as aluminum nitride, boron nitride, or silicon nitride, an inorganic substance such as silicon carbide or aluminum hydroxide, or an organic substance such as acrylic rubber, as described later, can be used. A thermally conductive adhesive tape obtained by filling a polymer resin with a material surface-treated with a silane coupling agent or the like may be used.

The adhesive tape having no thermal conductivity cannot be used because heat generated by the light emission of the LED is not sufficiently thermally conducted to the case, and the temperature of the LED rises. According to the results of the investigation by the present inventors, it is preferable to use a thermally conductive adhesive tape having a thermal conductivity of 1 to 2W/mK and a thickness of 50 to 150 μm.

The thermally conductive adhesive tape 37 is characterized in that an adhesive tape having a higher thermal conductivity than a conventional adhesive tape is used in order to efficiently dissipate heat generated when the LED emits light from the back surface of the metal base circuit board to the case through the metal base circuit board.

The polymer material used for the thermally conductive adhesive tape 37 is not particularly limited, and acrylic acid and/or methacrylic acid-containing polymers are preferably selected in order to improve adhesion to metals. That is, it is preferably an acrylic acid ester or methacrylic acid ester having an alkyl group having 2 to 12 carbon atoms, or an alkyl acrylate or methacrylic acid ester having 2 to 12 carbon atoms.

From the viewpoint of flexibility and processability, the monomer is preferably used in combination with 1 or 2 or more monomers selected from ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, decyl (meth) acrylate, and dodecyl (meth) acrylate. Among them, the monomer is more preferably 2-ethylhexyl acrylate.

The thermally conductive adhesive tape 37 preferably contains a thermally conductive electrical insulating agent. The thermally conductive electrical insulating agent may be any inorganic or organic substance as long as it is excellent in electrical insulating properties and thermal conductivity, and the organic substance is preferably a natural rubber, a rubber such as NBR or EPDM, and particularly preferably contains an acrylic rubber. Further, since good heat dissipation can be ensured, the thermally conductive electrical insulating agent is preferably contained in the adhesive tape 37 in an amount of 40 to 80 vol%. The range of 50 to 70 vol% is more preferable.

Examples of the monomer for the acrylic rubber include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, cyanomethyl acrylate, 1-cyanoethyl acrylate, 2-cyanoethyl acrylate, 1-cyanopropyl acrylate, and 2-cyanopropyl acrylate. The acrylic rubber is preferably obtained by copolymerizing 1 or more kinds of monomers selected from them in combination or a few% of crosslinking point monomers. The rubber content in the thermally conductive adhesive tape 37 is preferably 0.1 to 30 parts by mass. If the amount is less than 0.1 part by mass, the filler precipitates after the high-thermal-conductivity filler is filled in the polymer resin material, and if the amount exceeds 30 parts by mass, the viscosity increases, which causes a problem during processing. When the rubber content is 0.1 to 30 parts by mass, not only the filler precipitation can be prevented, but also the processability is good.

The monomer is preferably an acrylic acid ester or methacrylic acid ester having an alkyl group having 2 to 12 carbon atoms, or an alkyl acrylate or methacrylic acid ester having 2 to 12 carbon atoms, from the viewpoint of flexibility and adhesiveness. Preferred monomers from the viewpoint of flexibility and adhesion are 1 or 2 or more selected from the group consisting of ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, decyl methacrylate and dodecyl methacrylate. A more preferred monomer is 2-ethylhexyl acrylate.

Examples of the inorganic substance used as the thermally conductive electrical insulating agent include metal oxides such as alumina and titania, nitrides such as aluminum nitride, boron nitride and silicon nitride, silicon carbide and aluminum hydroxide. Among them, 1 or more selected from the group consisting of alumina, crystalline silica and aluminum hydroxide is preferred. Further, a material surface-treated with a silane coupling agent or the like may be selected.

In addition, the size of the thermally conductive electrical insulating agent is preferably 45 μm or less in maximum particle diameter and 0.5 to 30 μm in average particle diameter from the viewpoint of thickness and filling property of the adhesive tape.

The thermally conductive adhesive tape 37 may contain a known polymer compound within a range not to impair the characteristics targeted by the present invention. If necessary, known additives may be added to the thermally conductive adhesive tape 37 within a range that does not affect the curing. Examples of the additives include various additives for controlling viscosity and viscosity, and modifiers, antioxidants, heat stabilizers, and colorants.

The thermally conductive adhesive tape 37 may be cured by a general method. For example, the curing can be carried out by thermal polymerization using a thermal polymerization initiator, photopolymerization using a photopolymerization initiator, polymerization using a thermal polymerization initiator and a curing accelerator, and the like.

Examples

The following examples are illustrative, but the present invention is not limited to these examples.

< Metal base Circuit Board >

[ example 1-1]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, wherein 63 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000: 6: 4 by mass ratio) as a curing agent was added to 100 parts by mass of a bisphenol A type epoxy resin (manufactured by Dainippon ink chemical industries, Ltd.: EPICLON830-S) having an epoxy equivalent of 187, and pulverized alumina (manufactured by Showa Denko K.K.: AL-173) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated into the insulating layer so as to reach 50% by volume, and the cured thickness was 100 μm. Next, an electrolytic copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating to obtain a metal base substrate. Then, the obtained metal base substrate was masked with a resist at a predetermined position, and the copper foil was etched, followed by removing the resist to form a circuit, thereby completing a metal base circuit substrate.

The metal base circuit board thus obtained was examined for (1) bendability at room temperature, (2) thermal conductivity of the insulating layer, (3) adhesion strength between the conductor circuit and the insulating layer, (4) glass transition temperature of the insulating layer, (5) insulating layer breakdown voltage after heat treatment at 260 ℃ for 10 minutes, (6) insulating layer withstand voltage value in a state of being bent at 90 ° at room temperature, (7) insulating layer breakdown time in a state of being applied with dc voltage 1000V (pattern side +) at 125 ℃, and (8) presence or absence of insulating layer cracking in a state of being bent at 90 ° at room temperature, by the following methods.

These results are shown in tables 1-2. The obtained metal base circuit board was excellent in all physical properties.

(1) Regarding the bendability at room temperature, it is considered that a metal base circuit board is processed to 10mm × 100mm, and can be bent at a radius of curvature of 5mm or more to the conductor circuit forming surface side and the opposite side to the conductor circuit forming surface by both hands in a temperature atmosphere of 25 ± 1 ℃ by 90 ° or more, and that a mold or a press for bending is required to be used when bending is performed, and the like is considered to be poor.

(2) For the measurement of the thermal conductivity, the metal foil as the base material of the metal base circuit board and the conductor circuit were removed, the insulating layer was processed to have a diameter of 10mm × 100 μm (a portion of 60 μm), and the thickness was determined by the laser flash method.

(3) The bonding strength between the conductor circuit and the insulating layer was determined by processing the conductor circuit of the metal base circuit board into a strip shape having a width of 10mm by a method prescribed in JIS C6481.

(4) The glass transition temperature (Tg) was measured by a dynamic elasticity measurement method in which the metal foil as a base material of the metal base circuit board and the conductor circuit were removed, the insulating layer was processed to 5mm × 50mm × 100 μm (portion 60 μm), and the thickness was measured.

(5) For the measurement of the dielectric breakdown voltage after the heat treatment at 260 ℃ for 10 minutes, a metal base circuit board having a conductor circuit with a circular pattern of phi 20mm was placed in a soldering bath heated to 260 ℃ for 10 minutes, cooled to room temperature, and then the withstand voltage between the circular pattern and an aluminum foil was measured by the step-up method specified in JIS C2110.

(6) For the measurement of the withstand voltage value of the insulating layer in the state of being bent at 90 ° at room temperature, the withstand voltage between the circular pattern and the aluminum foil was measured by the step-up method specified in JIS C2110 in a state in which the circular pattern of Φ 20mm including the metal base circuit board in which the circular pattern of Φ 20mm was formed as the conductor circuit was bent at 90 ° with a radius of curvature of 1 mm.

(7) The insulation layer breakdown time was measured when a DC voltage of 1000V (pattern side +) was applied at 125 ℃ by setting the circular pattern side of a metal base circuit board on which a circular pattern of 20mm was formed as a conductor circuit to + and the metal foil side to-1000V at 125 ℃.

(8) The presence or absence of cracking of the insulating layer in a state bent at 90 ° at room temperature was observed by naked eyes.

[ examples 1-2]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, to 100 parts by mass of a hydrogenated bisphenol A type epoxy resin (designated as hydrogenated in Table 1, manufactured by epoxy resins Co., Ltd.: YX-8000) having an epoxy equivalent of 201, 63 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン, D-400 and D-2000, mass ratio of 6: 4) as a curing agent was added, and pulverized alumina (manufactured by SHOWA and electrician Co., Ltd.: AL-173) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated in the insulating layer so as to be 50% by volume, and the cured thickness was 100 μm. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The bendability at room temperature is significantly improved due to the decrease in the glass transition temperature (Tg) of the insulating layer. Other physical properties were also good.

[ examples 1 to 3]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, wherein 48 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000 in a mass ratio of 6: 4) as a curing agent was added to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 201 (manufactured by Nippon epoxy resins Co., Ltd.: YX-8000) and a bisphenol A type epoxy resin having an epoxy equivalent of 1900 (manufactured by Tokyo chemical Co., Ltd.: YD-927H) to 50% by volume, and crushed alumina having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm (manufactured by Showa electric Co., Ltd.: AL-173) was incorporated in the insulating layer to give a thickness of 100 μm after curing. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The adhesion strength between the conductor circuit and the insulating layer of the metal base circuit board obtained is remarkably improved. Other physical properties were also good.

[ examples 1 to 4]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, wherein 50 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン; D-400; D-2000: 6: 4 by mass ratio) as a curing agent was added to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 201 of 70% by mass (manufactured by Nippon epoxy resins Co., Ltd.: YX-8000) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1024 of 30% by mass (manufactured by Tokyo chemical Co., Ltd.: ST-4100D) to incorporate crushed alumina having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm (manufactured by Showa electric Co., Ltd.: AL-173) in an amount of 50% by volume in the insulating layer, and the cured thickness was 100 μm. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The metal base circuit board obtained has improved adhesion strength between the conductor circuit and the insulating layer, and also has significantly improved bendability at room temperature due to a decrease in the glass transition temperature (Tg) of the insulating layer. Other physical properties were also good.

[ examples 1 to 5]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, wherein 55 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000 at a mass ratio of 6: 4) as a curing agent was added to 100 parts by mass of an epoxy resin composed of 70% by mass of a hydrogenated bisphenol F type epoxy resin having an epoxy equivalent of 181 (manufactured by Nippon epoxy resins Co., Ltd.: YL-6753) and 30% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1024 (manufactured by Tokyo chemical Co., Ltd.: ST-4100D) in the entire epoxy resin, and crushed alumina (manufactured by Showa electric company: AL-173) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated in the insulating layer so as to be 50% by volume, and the cured thickness was 100 μm. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The metal base circuit board obtained has improved adhesion strength between the conductor circuit and the insulating layer, and also has significantly improved bendability at room temperature due to a decrease in the glass transition temperature (Tg) of the insulating layer.

[ examples 1 to 6]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, in which 48 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000 at a mass ratio of 6: 4) as a curing agent was added to 100 parts by mass of an epoxy resin composed of 70% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 (manufactured by Dainippon ink chemical industries Co., Ltd.: EXA-7015) and 30% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 (manufactured by Nippon epoxy resins Co., Ltd.: YL-7170), and pulverized alumina (manufactured by Showa electric industries Co., Ltd.: AL-173) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated in the insulating layer so as to be 50% by volume, and the chloride ion concentration of the whole thermosetting resin was 250ppm, the thickness after curing was 100. mu.m. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The metal base circuit board obtained has improved adhesion strength between the conductor circuit and the insulating layer, and also has significantly improved bendability at room temperature due to a decrease in the glass transition temperature (Tg) of the insulating layer. Further, the breakdown time of the insulating layer when a dc voltage of 1000V (pattern side +) is applied at 125 ℃ is prolonged. Other physical properties were also good.

[ examples 1 to 7]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm by combining 48 parts by mass of polyoxypropylene diamine (manufactured by Showa Denko K.K.: D-400 and D-2000 at a mass ratio of 6: 4) as a curing agent with coarse-grained alumina (CB-A20) having a maximum grain size of 75 μm or less and an average grain size of 21 μm and a sodium ion concentration of 10ppm and fine-grained alumina (manufactured by Sumitomo Denko K.: AKP-15) having an average grain size of 0.7 μm and a sodium ion concentration of 8ppm so as to achieve 50 parts by mass in the insulating layer, with respect to 100 parts by mass of an epoxy resin composed of 70% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 (manufactured by Dainippon ink chemical industries Co., Ltd.: EXA-7015) and 30% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 (manufactured by Nippon epoxy resins Co., Ltd.: YL-7170) Volume% (mass ratio of spherical coarse particles to spherical fine particles: 7: 3) of the mixture, and the thickness after curing was 100 μm. Next, an electrolytic copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating to obtain a metal base substrate in which the chloride ion concentration of the whole thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the whole inorganic filler in the insulating layer was 50ppm or less, and a metal base circuit substrate was produced by the same method as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The obtained metal base circuit board has remarkably prolonged breakdown time of the insulating layer when a DC voltage of 1000V (pattern side +) is applied at 125 ℃, and has good other physical properties.

[ examples 1 to 8]

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm by combining 48 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000: mass ratio of 6: 4) as a curing agent with respect to 100 parts by mass of an epoxy resin composed of 170ppm of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 of 70% by mass (EXA-7015 manufactured by Dainippon ink chemical industries Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 of 30% by mass (YL-7170 manufactured by Nippon epoxy resins Co., Ltd.), spherical coarse alumina having a maximum particle diameter of 75 μm or less and an average particle diameter of 21 μm and a sodium ion concentration of 10ppm (manufactured by Showa Denko K.K.: CB-A20) and spherical fine particles having an average particle diameter of 0.7 μm and a sodium ion concentration of 8ppm (manufactured by Sumitomo chemical Co., Ltd.) so as to reach 66% by volume in the insulating layer (spherical fine particles) (manufactured by CB-A-15) The mass ratio of coarse particles to spherical fine particles was 7: 3), and the thickness after curing was 100 μm. Next, an electrolytic copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating to obtain a metal base substrate in which the chloride ion concentration of the whole thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the whole inorganic filler in the insulating layer was 60ppm or less, and a metal base circuit substrate was produced by the same method as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The thermal conductivity of the metal base circuit board obtained is further improved, and other physical properties are also good.

Comparative examples 1 to 1

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 400 μm, wherein 63 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000: 6: 4 by mass ratio) as a curing agent was added to 100 parts by mass of a bisphenol A type epoxy resin (manufactured by Dainippon ink chemical industries, Ltd.: EPICLON850-S) having an epoxy equivalent of 187, and pulverized alumina (manufactured by Showa Denko K.K.: AL-l73) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated into the insulating layer so as to reach 80% by volume, and the cured thickness was 100 μm. Then, an electrolytic copper foil having a thickness of 210 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The obtained metal base circuit board had almost no bendability, could not be bent by hand at room temperature, and was bent to 90 ° using a bending die and a press. In addition, the adhesive strength between the conductor circuit and the insulating layer is weak, and the insulating layer has an extremely low withstand voltage value in a state of being bent at 90 ° at room temperature. Further, the breakdown time of the insulating layer when a dc voltage of 1000V (pattern side +) is applied at 125 ℃ is also extremely short. In addition, the thermal conductivity is locally different, and the deviation is large.

Comparative examples 1 and 2

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 40 μm, wherein 63 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン: D-400 and D-2000: 6: 4 by mass ratio) as a curing agent was added to 100 parts by mass of a bisphenol A type epoxy resin (manufactured by Dainippon ink chemical industries, Ltd.: EPICLON850-S) having an epoxy equivalent of 187, and crushed alumina (manufactured by Showa Denko K.K.: A-13-L) having an average particle diameter of 57 μm and a maximum particle diameter of 90 μm was incorporated into the insulating layer so as to reach 50% by volume, and the cured thickness was 60 μm. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. In the obtained metal base circuit board, a large number of projections and recesses, which are considered to be protrusions of the alumina filler, were confirmed in the exposed portion of the insulating layer on the conductor circuit surface, and cracks were generated in the insulating layer when the board was bent at room temperature. In addition, the adhesive strength between the conductor circuit and the insulating layer is weak, and the insulating layer has an extremely low withstand voltage value in a state of being bent at 90 ° at room temperature. Further, the breakdown time of the insulating layer when a dc voltage of 1000V (pattern side +) is applied at 125 ℃ is also extremely short.

Comparative examples 1 to 3

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 400 μm, wherein 51 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン, D-400 and D-2000, at a mass ratio of 6: 4) as a curing agent was added to 100 parts by mass of an epoxy resin composed of 40% by mass of a bisphenol A type epoxy resin having an epoxy equivalent of 187 (manufactured by Dainippon ink chemical industries, Ltd.: EPICLON850-S) and 60% by mass of a bisphenol A type epoxy resin having an epoxy equivalent of 4000 (manufactured by Nippon epoxy resins, Ltd.: エピコ - ト 1010), and crushed alumina (manufactured by Showa Denko K Co., Ltd.: AL-173) having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm was incorporated in the insulating layer so as to be 50% by volume, and the cured thickness was 100 μm. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The obtained metal base circuit board has almost no bendability, and cannot be bent by hand at room temperature, but is bent to 90 ° using a bending die and a press, but the glass transition temperature (Tg) is increased, the bendability at room temperature is insufficient, and the withstand voltage of the insulating layer in a state of being bent to 90 ° at room temperature is significantly lowered.

Comparative examples 1 to 4

As shown in Table 1-1, an insulating layer was formed on an aluminum foil having a thickness of 400 μm, wherein 42 parts by mass of polyoxypropylene diamine (product of ハルツマン: D-400 and D-2000 in a mass ratio of 6: 4) as a curing agent was added to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin (product of Kyowa Kagaku K.K.: EPOLIGHT4000) having an epoxy equivalent of 70% by mass and a chloride concentration in the resin of 1500ppm and a bisphenol F type epoxy resin (product of Nippon epoxy resin Co., Ltd.: エピコ - ト 4004P) having a chloride concentration of 30% by mass and a chloride concentration in the resin of 920ppm, and crushed alumina having an average particle diameter of 2.2 μm and a maximum particle diameter of 20 μm (product of Heat curing Showa Denko K.: AL-173) was incorporated into the insulating layer so as to reach 50% by volume, and the chloride ion concentration of the whole resin was 1000ppm, the thickness after curing was 100. mu.m. Then, an electrolytic copper foil having a thickness of 35 μm was bonded, the insulating layer was thermally cured by heating to obtain a metal base substrate, and a metal base circuit board was produced in the same manner as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The time for breakdown of the insulating layer when a DC voltage of 1000V (pattern side +) is applied at 125 ℃ to the metal base circuit board obtained is extremely short.

Comparative examples 1 to 5

As shown in Table 1-1, an insulating layer was formed on an aluminum foil 400 μm thick by combining a coarse-grained alumina (made by MICRON corporation: AX-25) having a maximum particle diameter of 75 μm or less and an average particle diameter of 25 μm and a sodium ion concentration of 530ppm and a fine-grained alumina (made by MICRON corporation: AW15-25) having an average particle diameter of 1.2 μm and a sodium ion concentration of 396ppm with a polyoxypropylene diamine (made by ハルツマン corporation: D-400 and D-2000: 6: 4) as a curing agent in an amount of 63 parts by mass based on 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin (made by CO., Ltd.: EPOLIGHT4000) having an epoxy equivalent of 70% by mass and a chloride concentration of 1500ppm in the resin (made by CO., Ltd.: エピコ - ト 4004P) and a bisphenol F type epoxy resin (made by Nippon epoxy resin Co., Ltd.: エピコ - ト P) having a chloride concentration of 920ppm in the resin, and an average particle diameter of 75 ppm, to form an insulating layer, and to form an insulating To 50 vol% (mass ratio of spherical coarse particles to spherical fine particles: 7: 3), and the thickness after curing was 100. mu.m. Next, an electrolytic copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating to obtain a metal base substrate having a chloride ion concentration of 1000ppm in the entirety of the thermosetting resin in the insulating layer and a sodium ion concentration of 500ppm in the entirety of the inorganic filler in the insulating layer, and a metal base circuit substrate was produced by the same method as in example 1-1 to measure various physical properties.

These results are shown in tables 1-2. The resulting metal base circuit board had a very short breakdown time of the insulating layer when a dc voltage of 1000V (pattern side +) was applied at 125 ℃.

The thickness of each layer of the metal base circuit board, the type and amount of the thermosetting resin incorporated, the concentration of chloride ions contained, the type of the inorganic filler and the concentration of sodium ions contained are shown in Table 1-1.

The physical properties of the resulting metal base circuit board are shown in tables 1 to 2.

< multilayer Circuit Board >

(example 2-1)

An insulating layer was formed on a copper foil having a thickness of 35 μm, wherein 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000") as a curing agent was added in a mass ratio of 6: 4 in combination with alumina having spherical coarse particles having a maximum particle diameter of 75 μm or less ("CB-A20" manufactured by Showa Denko K.K.) and an alumina having spherical fine particles having an average particle diameter of 0.6 μm ("AO-802" manufactured by Admatech corporation) so as to reach 50% by volume (the mass ratio of spherical coarse particles to spherical fine particles is 6: 4) in the insulating layer, relative to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 201 ("YX-8000" manufactured by Nippon epoxy resins Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resins Co., Ltd.), the thickness after curing was 100. mu.m. Subsequently, a copper foil having a thickness of 35 μm was laminated, and the insulating layer was thermally cured by heating to obtain an inner-layer-laminated substrate.

Then, the obtained substrate was masked with a dry film at a predetermined position, and the copper foil was etched to remove the dry film to form a circuit, thereby forming an inner layer circuit substrate.

The insulating layer and a copper foil having a thickness of 35 μm were laminated on the obtained inner layer circuit board as a base, and then cured by heating to obtain a multilayer board.

Then, a hole having a diameter of 0.5mm was drilled at a predetermined position of the outer layer circuit by a drill, and the inner layer circuit and the outer layer circuit were penetrated, followed by copper plating to form a through hole. And etching the outer layer circuit on the surface of the substrate by the method to obtain the multilayer circuit substrate.

With respect to the multilayer circuit board, (1) the thermal conductivity of the insulating layer, (2) the glass transition temperature of the insulating layer, (3) the withstand voltage at the time of bending, (4) the bendability, and (5) the operation stability of the power element were measured and evaluated by the following methods.

(1) Thermal conductivity measurement of insulating layer

The insulating layer of the circuit board was separately prepared as a disk-shaped cured body having a diameter of 10mm × a thickness of 2mm, and the thickness was determined by a laser flash method.

(2) Glass transition temperature of insulating layer

The metal foil as a base material and the conductor circuit were removed by etching using a circuit board of one layer before multilayering, and the insulating layer taken out was processed to 5mm × 50mm and determined by a dynamic viscoelasticity measurement method.

(3) Withstand voltage during bending

The withstand voltage between the inner layer circuit and the aluminum foil was measured by the step-up method specified in JIS C2110 in a state in which the multilayer circuit board including the circular pattern having a diameter of 20mm formed as the outer layer circuit was bent at 90 ° with a radius of curvature of 1 mm.

(4) Bendability at room temperature

A multilayer circuit board (a board using a conductor foil having a whole surface without forming a circuit pattern on the inner layer and the outer layer) is processed to 10mm × 100mm, and it is considered to be good that the multilayer circuit board can be bent by both hands at a radius of curvature of 5mm or more to the conductor circuit forming surface side and the opposite side to the conductor circuit forming surface in a temperature atmosphere of 25 ± 1 ℃, and it is considered to be poor that a die or a press for bending is required when the multilayer circuit board is bent.

(5) Operation stability of power element

A module was prepared in which 3 p-mos-FETs (2SK2174S) manufactured by Hitachi Seisakusho were mounted at intervals of 2mm, and the module was continuously operated at 100 ℃ for 96 hours under a condition of consuming 10W of power per 1 element to evaluate the presence or absence of malfunction. When no malfunction occurred, 10W of power consumption was added and the evaluation was performed again to evaluate the operation stability of the power element based on the amount of power consumption at the time of malfunction.

These results are shown in Table 2-1.

TABLE 2-1

(example 2-2)

Except that the composition of the insulating layer was blended under the condition of reaching 65 volume% in the insulating layer (mass ratio of coarse spherical and spherical fine particles of 6: 4) by combining alumina having spherical coarse particles with a maximum particle diameter of 75 μm or less (CB-A20 manufactured by Sho-and electrician corporation) and alumina having spherical fine particles with an average particle diameter of 21 μm (AO-802 manufactured by Admatech corporation) with 48 parts by mass of polyoxypropylene diamine (mass ratio of 6: 4) as a curing agent, which was "D-400" and "D-2000" manufactured by ハルツマン corporation) and was mixed with 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin with an epoxy equivalent of 201 (manufactured by Nippon epoxy resins corporation) and 30% by mass of a hydrogenated bisphenol A type epoxy resin with an epoxy equivalent of 1200 (manufactured by Nippon epoxy resins) (mass ratio of 6: 4), a multilayer circuit board was produced in the same manner as in example 2-1, and evaluated in the same manner as in example 2-1. The results are shown in Table 2-1.

(examples 2 to 3)

In addition to the addition of 63 parts by mass of polyoxypropylene diamine (manufactured by ハルツマン company, "D-400" and "D-2000" having a mass ratio of 6: 4) as a curing agent, in combination with alumina of spherical coarse particles having a maximum particle diameter of 75 μm or less ("CB-A20" manufactured by SHOWA and electrician company) and alumina of spherical fine particles having an average particle diameter of 0.6 μm ("AO-802" manufactured by Admatechs company) to 100 parts by mass of a bisphenol A type epoxy resin (manufactured by Japan ink chemical industry Co., Ltd.: EPICLON850-S) having an epoxy equivalent of 187, under the condition that 50% by volume of the insulating layer is achieved (the mass ratio of spherical coarse particles to spherical fine particles is 6: 4), a multilayer circuit board was produced in the same manner as in example 2-1, and evaluated in the same manner as in example 2-1. The results are shown in Table 2-1.

(examples 2 to 4)

Except that 60 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" are added as a curing agent in a mass ratio of 6: 4) to 100 parts by mass of a hydrogenated bisphenol A type epoxy resin ("YX-8000" manufactured by epoxy resin company, Japan) having an epoxy equivalent of 201, alumina (CB-A20 "manufactured by Showa Denko K.K.) as a coarse spherical particle having a maximum particle diameter of 75 μm or less and an alumina (AO-802" manufactured by Admatechs company) as a fine spherical particle having an average particle diameter of 0.6 μm are incorporated under the condition that 50% by volume (mass ratio of coarse spherical particle to fine spherical particle is 6: 4) is achieved in an insulating layer, a multilayer circuit board was produced in the same manner as in example 2-1, and evaluated in the same manner as in example 2-1. The results are shown in Table 2-1.

Comparative example 2-1

In addition to the addition of 63 parts by mass of polyoxypropylene diamine as a curing agent (the mass ratio of "D-400" and "D-2000" manufactured by ハルツマン Co., Ltd., is 6: 4) to 100 parts by mass of bisphenol A type epoxy resin (manufactured by Dainippon ink chemical industry Co., Ltd., product: EPICLON850-S) having an epoxy equivalent of 187, alumina (CB-A20 manufactured by Showa Denko K.K.; product) as a coarse spherical particle having a maximum particle diameter of 75 μm or less and alumina (AO-802 manufactured by Admatech Co., Ltd., product: 0.6 μm) as a fine spherical particle having an average particle diameter of 0.6 μm were combined so as to be incorporated in an insulating layer in such a manner as to reach 80% by volume (the mass ratio of coarse spherical particle to fine spherical particle: 6: 4), a multilayer circuit board was produced in the same manner as in example 2-1, and evaluated in the same manner as in example 2-1. The results are shown in Table 2-1. The obtained multilayer circuit board had almost no flexibility, could not be bent by hand at room temperature, and was bent to 90 ° using a bending die and a press. In addition, the withstand voltage is low.

Comparative examples 2 and 2

Evaluation was carried out in the same manner as in example 2-1 except that an insulating layer was formed on an Al plate having a thickness of 1500. mu.m. The results are shown in Table 2-1. The obtained multilayer circuit board had almost no flexibility, could not be bent by hand at room temperature, and was bent to 90 ° using a bending die and a press. Various characteristics of the multilayer circuit substrate are shown in Table 2-1.

< LED Module >

(example 3-1)

An insulating layer was formed on a copper foil 18 μm thick, in which 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" in a mass ratio of 6: 4) as a curing agent and 48 parts by mass of coarse spherical alumina having a maximum particle diameter of 30 μm or less and an average particle diameter of 10 μm and a sodium ion concentration of 90ppm (DAW-10 manufactured by electro-chemical industries Co., Ltd.) were combined with coarse spherical alumina having an average particle diameter of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) so as to reach 50% by volume in the insulating layer (coarse spherical alumina: AKP-15) with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resins ", manufactured by Nippon epoxy resins, Inc.) The mass ratio of the pellets to the spherical fine particles was 7: 3), and the thickness after curing was 50 μm.

Then, a copper foil having a thickness of 18 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit. Then, a coating layer (NIKAFLEX CKSE) having a thickness of 12.5 μm was applied to the metal base circuit board except for the component mounting portion and the input terminal portion, thereby reinforcing the board.

Next, using a press punching apparatus equipped with a thomson die having the same shape as the desired slit shape, the metal foil, the insulating layer, and the coating layer were removed from the portions where the conductor circuit and the electrodes were not formed, and the metal-based circuit board was processed to 80% of the length of the bent portion, and was obtained to include the slit portion obtained by the processing and to be easily bent.

Then, a solder paste ("M705" made by kokusan metal corporation) was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board, and an LED ("NFSW 036B" made by riyaku corporation) was mounted by reflow soldering. Then, the metal base circuit board was bent at a radius of curvature of 0.3mm using a stainless bending tool having a width of 200mm and a thickness of 0.6mm and a radius of curvature of 0.3mm in a state including the slit portion, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, thereby obtaining an LED module.

The tensile strength at room temperature, (2) the bendability at room temperature, (3) the evaluation of the conductor circuit, (4) the withstand voltage at the time of bending, and (5) the electromagnetic wave absorption characteristics were measured by the following methods.

(1) Tensile strength at room temperature

The tensile strength was determined by processing a metal base circuit board to 10mm × 100mm and measuring the strength at which the metal base circuit board broke by a TENSILON tensile strength tester in an atmosphere at a temperature of 25 ± 1 ℃.

(2) Bendability at room temperature

The metal base circuit board is processed to 10mm × 100mm, and it is considered to be good that the metal base circuit board can be bent by two hands at a radius of curvature of 0.5mm or more by 90 ° or more to the conductor circuit forming surface side and the opposite side to the conductor circuit forming surface in a temperature atmosphere of 25 ± 1 ℃.

(3) Evaluation of conductor circuits

The obtained LED module is connected with a stable power supply under the temperature atmosphere of 25 +/-1 ℃, and the LED is lightened for more than 1 hour through 10V voltage and 150mA current. In this case, the case where the LED was turned on for 1 hour or more was regarded as good, and the case where the LED was not turned on or was not turned on for 1 hour or more was regarded as bad.

(4) Withstand voltage during bending

The withstand voltage between the conductor circuit and the base metal foil (Cu foil) was measured by a step-up method specified in JIS C2110 in a state where the metal base circuit board was bent at 90 ° with a radius of curvature of 0.3 mm.

(5) Electromagnetic wave absorption characteristics

For the obtained substrate, electromagnetic wave absorption characteristics were measured for frequencies of 300MHz and 1GHz using a network analyzer (8517D, agilent technologies). The absorption characteristics were measured by the microstrip line method, and the absorption ratio (Ploss/Pin) was calculated from the measurement results of the reflected signal S11 and the transmitted signal S21 of the electromagnetic wave on the line.

These results are shown in Table 3-1.

TABLE 3-1

(example 3-2)

An insulating layer was formed on a copper foil 18 μm thick, in which 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" in a mass ratio of 6: 4) as a curing agent and 48 parts by mass of coarse spherical alumina having a maximum particle diameter of 30 μm or less and an average particle diameter of 10 μm and a sodium ion concentration of 90ppm (DAW-10 manufactured by electro-chemical industries Co., Ltd.) were combined with coarse spherical alumina having an average particle diameter of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) so as to reach 50% by volume in the insulating layer (coarse spherical alumina: AKP-15) with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resins ", manufactured by Nippon epoxy resins, Inc.) The mass ratio of the pellets to the spherical fine particles was 7: 3), and the thickness after curing was 50 μm. Then, a copper foil having a thickness of 18 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit. Then, a coating layer (NIKAFLEX CKSE) having a thickness of 12.5 μm was applied to the metal base circuit board except for the component mounting portion and the input terminal portion, thereby reinforcing the board.

Next, a layer having a magnetic loss of 30 μm thick and containing 50% by volume of the magnetic material, which is composed of a magnetic material having an aspect ratio of 4 and an organic binder material, was formed on the upper surface of the coating layer.

Next, a stainless bending tool having a width of 200mm and a thickness of 0.6mm and a radius of curvature of 0.3mm was used to remove a portion of the metal foil, the insulating layer, the coating layer, and the layer having magnetic loss at a position where the conductor circuit and the electrode were not formed, and the metal base circuit board was processed to have a length of 80% with respect to the bent portion, thereby obtaining a metal base circuit board including a slit portion obtained by the processing and capable of being easily bent.

Next, a solder paste was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board ("M705" manufactured by henya chemical corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm in a state including the slit portion, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

(examples 3 to 3)

An insulating layer was formed on a copper foil 18 μm thick, in which 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" in a mass ratio of 6: 4) as a curing agent and 48 parts by mass of coarse spherical alumina having a maximum particle diameter of 30 μm or less and an average particle diameter of 10 μm and a sodium ion concentration of 90ppm (DAW-10 manufactured by electro-chemical industries Co., Ltd.) were combined with coarse spherical alumina having an average particle diameter of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) so as to reach 50% by volume in the insulating layer (coarse spherical alumina: AKP-15) with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resins ", manufactured by Nippon epoxy resins, Inc.) The mass ratio of the pellets to the spherical fine particles was 7: 3), and the thickness after curing was 50 μm. Then, a copper foil having a thickness of 18 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit. Then, a coating layer (NIKAFLEX CKSE) having a thickness of 12.5 μm was applied to the metal base circuit board except for the component mounting portion and the input terminal portion, thereby reinforcing the board.

Then, a carbon powder having a specific surface area of 100m was formed on the upper surface of the coating layer²A layer having a dielectric loss of 30 μm thickness containing 50 vol% of carbon powder, which is formed of carbon black in which boron is solid-dissolved and has a resistivity of 0.1. omega. cm or less in accordance with JIS K1469, and an organic binder.

Next, a bending tool made of stainless steel having a width of 200mm and a thickness of 0.6mm and a radius of curvature of 0.3mm was used to remove a portion of the metal foil, the insulating layer, the coating layer, and the layer having dielectric loss at a position where the conductor circuit and the electrode were not formed, and the metal base circuit board was processed to a length of 80% with respect to the bent portion, thereby obtaining a metal base circuit board including a slit portion obtained by the processing and capable of being easily bent.

Next, a solder paste was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board ("M705" manufactured by henya chemical corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm in a state including the slit portion, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

Comparative example 3-1

A metal base circuit board was obtained by performing all the same processes as in example 3-1, except that the substrate was not reinforced by attaching a coating layer and the slit processing of the bent portion was not performed.

Next, a solder paste was applied to the electrodes of the component mounting portion of the metal base circuit board by screen printing ("M705" manufactured by zukka corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

Comparative example 3-2

A metal base circuit board was obtained by performing the same processing as in example 3-1 except that the slit processing of the bent portion was not performed.

Next, a solder paste was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board ("M705" manufactured by henya chemical corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

Comparative examples 3 to 3

A metal base circuit board was obtained by performing the same treatment as in example 3-2 except that a2 μm thick layer having a magnetic loss was formed on the upper surface of the coating layer, the layer being formed of a magnetic material having an aspect ratio of 1 and an organic binder, and the content of the magnetic material being 20 vol%.

Next, a solder paste was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board ("M705" manufactured by henya chemical corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm in a state including the slit portion, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

Comparative examples 3 to 4

Except that the coating layer is formed on the substrate with a specific surface area of 10m²A metal base circuit board was obtained by carrying out the same treatment as in examples 3 to 3 except that a layer having a dielectric loss of 2 μm thickness containing 4% by volume of the carbon powder was formed of carbon black in boron solid solution and an organic binder and having a volume resistivity of 0.2. omega. cm in accordance with JIS K1469.

Next, a solder paste was applied by screen printing to the electrodes of the component mounting portion of the metal base circuit board ("M705" manufactured by henya chemical corporation), and an LED was mounted by reflow soldering ("NFSW 036B" manufactured by riyas chemical corporation). Then, the metal base circuit board was bent at a radius of curvature of 0.3mm in a state including the slit portion, and fixed to an aluminum case having a thickness of 1mm using a heat conductive adhesive tape, to obtain an LED module. The results of the evaluations conducted in the same manner as in example 3-1 are shown in Table 3-1.

< LED light Source Unit >

(example 4-1)

An insulating layer was formed on a copper foil having a thickness of 35 μm by combining alumina having a spherical coarse particle size of 75 μm or less in maximum particle size and having an average particle size of 21 μm and a sodium ion concentration of 10ppm (CB-A20 manufactured by Showa Denko K.K.: AKP-15) with alumina having a spherical fine particle size of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) in such a manner that 50% by volume of the spherical coarse particle size and the coarse particle size are obtained in the insulating layer, with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resin Co., 48 parts by mass of polyoxypropylene diamine ("D-400" and "D-2000" manufactured by ハルツマン Co., Ltd.) as a curing agent in a mass ratio of 6: 4 The mass ratio of the spherical fine particles was 7: 3), and the thickness after curing was 100 μm. Then, a copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit.

A thermally conductive adhesive tape was prepared by mixing 10 mass% of acrylic acid (AA, manufactured by Toyata Co., Ltd.) with 90 mass% of 2-ethylhexyl acrylate (2 EHA, manufactured by Toyata Co., Ltd.) in which 10 mass% of acrylic rubber (AR-53L, manufactured by ZEON Co., Ltd.) was dissolved, and further adding 0.5 mass% of 2, 2-dimethoxy-1, 2-diphenylethane-1-one (manufactured by Ciba Seikagaku Co., Ltd.), 0.2 mass% of triethylene glycol dithiol (manufactured by Takara chemical Co., Ltd.), and 0.2 mass% of 2-butyl-2-ethyl-1, 3-propanediol diacrylate (manufactured by Kyowa Co., Ltd.) as a photopolymerization initiator.

The resin composition was filled with 300 parts by mass of alumina ("DAW-10" manufactured by electrical chemical industries), mixed and dispersed to obtain a heat conductive resin composition.

The heat conductive resin composition was defoamed, coated on a polyester film having a thickness of 75 μm whose surface was subjected to a release treatment in a thickness of 100 μm, and coated on the polyester film whose surface was subjected to the release treatment, and the coating was 3000mJ/cm from both the front and back surfaces²Irradiating 365nm ultraviolet rays to obtain the heat-conducting adhesive tape.

A solder paste ("M705" manufactured by henya chemical company) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSWO 36 AT" manufactured by riyaku company) was mounted by reflow soldering. Then, the LED was fixed to a U-shaped case by a heat conductive adhesive tape having a heat conductivity of 1W/mK and a thickness of 100 μm on the side of the metal base circuit board on which the LED was not mounted, to obtain an LED light source unit.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 11.8V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the LED temperature was 45 ℃.

The measurement of (1) bendability at room temperature, (2) thermal conductivity of the insulating layer, (3) thermal conductivity of the thermally conductive adhesive tape, (4) presence or absence of cracking of the insulating layer when fixed to the U-shaped case at room temperature, and (5) LED temperature when the LED was turned on was performed by the following methods.

(1) Bendability at room temperature

It is considered that a metal base circuit board processed to 10mm × 100mm can be bent at a radius of curvature of 5mm or more to the conductor circuit forming surface side and the opposite side to the conductor circuit forming surface by both hands at a temperature of 25 ± 1 ℃ by 90 ° or more, and that the use of a die or press for bending is required when bending is performed, which is considered to be a problem.

(2) Thermal conductivity of insulating layer

The metal foil and the conductor circuit of the metal base circuit board were removed, and the insulating layer was processed to a diameter of 10mm × a thickness of 100 μm and determined by a laser flash method.

(3) Thermal conductivity of thermally conductive adhesive tape

The measurement samples were laminated at a thickness of 10mm, processed to 50mm × 120mm, and determined by a rapid thermal conductivity meter (QTM-500, manufactured by Kyoto electronics industries, Ltd.).

(4) Presence or absence of cracking of insulating layer

The presence or absence of cracking of the insulating layer in a state of being bent at 90 ° at room temperature was observed by naked eyes.

(5) LED temperature when LED is on

The LED was lighted by applying a rated current of 450mA, and the temperature of the LED soldered portion after 15 minutes was measured.

(example 42)

An insulating layer was formed on a copper foil having a thickness of 35 μm, in which 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" in a mass ratio of 6: 4) as a curing agent and alumina having a spherical coarse particle size of 75 μm or less in a maximum particle size of 21 μm and a sodium ion concentration of 10ppm (CB-A20 "manufactured by Showa Denko K.K.) and alumina having a spherical fine particle size of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo Denko Junyaku Denko) were combined to form an of an insulating layer having a thickness of 66% by volume (spherical coarse particle size and spherical coarse particle size of 0. In a mass ratio of 7: 3) was added, and the thickness after curing was 100 μm. Then, a copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 60ppm or less.

The metal base circuit board is manufactured by forming a mask with a resist at a predetermined position on one copper foil surface, etching the copper foil, and then removing the resist to form a circuit.

A solder paste ("M705" manufactured by henya chemical company) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSWO 36 AT" manufactured by riyaku company) was mounted by reflow soldering. Then, the LED light source unit was obtained by fixing the metal base circuit board on the side where the LEDs were not mounted to the U-shaped case with the thermally conductive adhesive tape having a thermal conductivity of 1W/mK and a thickness of 100 μm obtained in example 4-1.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 11.7V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the temperature of the LED was 43 ℃. The results of the evaluation are shown in Table 4-1. The temperature of the lit LED decreases due to the increase in the thermal conductivity of the insulating layer. Other physical properties were also good.

(examples 4 to 3)

An insulating layer was formed on a copper foil having a thickness of 35 μm by combining alumina having a spherical coarse particle size of 75 μm or less in maximum particle size and having an average particle size of 21 μm and a sodium ion concentration of 10ppm (CB-A20 manufactured by Showa Denko K.K.: AKP-15) with alumina having a spherical fine particle size of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) in such a manner that 50% by volume of the spherical coarse particle size and the coarse particle size are obtained in the insulating layer, with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resin Co., 48 parts by mass of polyoxypropylene diamine ("D-400" and "D-2000" manufactured by ハルツマン Co., Ltd.) as a curing agent in a mass ratio of 6: 4 The mass ratio of the spherical fine particles was 7: 3), and the thickness after curing was 100 μm. Then, a copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit.

A solder paste ("M705" made by kokusan metal corporation) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSW 036 AT" made by riyaku corporation) was mounted by reflow soldering. Then, the side of the metal base circuit board on which the LED was not mounted was fixed to a U-shaped case by a thermally conductive adhesive tape having a thermal conductivity of 2W/mK and a thickness of 100 μm, which will be described later, to obtain an LED light source unit.

The resin composition for a thermally conductive adhesive tape had the composition obtained in example 4-1 except that 400 parts by mass of alumina (DAW-10, manufactured by electrochemical industries) was used as a filler, and was obtained by the procedure shown in example 4-1.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 11.7V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the LED temperature was 42 ℃.

(examples 4 to 4)

An insulating layer was formed on a copper foil 35 μm thick, in which 48 parts by mass of polyoxypropylene diamine ("D-400" manufactured by ハルツマン company and "D-2000" were added as a curing agent in a mass ratio of 6: 4) to 100 parts by mass of an epoxy resin composed of 70% by mass of 170ppm of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink company) and 30% by mass of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resin company), and spherical coarse-grained alumina having a maximum particle diameter of 75 μm or less and an average particle diameter of 21 μm and a sodium ion concentration of 10ppm ("CB-A20" manufactured by Showa electrician company) and spherical fine-grained alumina having an average particle diameter of 0.7 μm and a sodium ion concentration of 8ppm (manufactured by Sumitomo chemical company: AKP-15) were combined to achieve 66% by volume in the insulating layer (coarse-grained and spherical fine-grained alumina having an average particle diameter of 0.7 μm The mass ratio of the particles was 7: 3), and the thickness after curing was 100. mu.m. Then, a copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 60ppm or less.

The metal base circuit board is manufactured by forming a mask with a resist at a predetermined position on one copper foil surface, etching the copper foil, and then removing the resist to form a circuit.

A solder paste ("M705" manufactured by henya chemical company) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSWO 36 AT" manufactured by riyaku company) was mounted by reflow soldering. Then, the LED light source unit was obtained by fixing the thermally conductive adhesive tape having a thermal conductivity of 2W/mK and a thickness of 100 μm obtained in example 4-3 to a U-shaped case on the side of the metal base circuit board on which the LED was not mounted.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 11.6V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the LED temperature was 38 ℃. The results of the evaluation are shown in Table 4-1. The temperature of the lit LED decreases due to the increase in the thermal conductivity of the insulating layer. Other physical properties were also good.

Comparative example 4-1

A polyimide-based flexible substrate (R-F775, manufactured by Sonk electric engineering Co., Ltd.) having a 35 μm thick copper foil formed on a 35 μm thick copper foil with a 50 μm thick polyimide-based insulating layer interposed therebetween was masked with a resist at a predetermined position, and the copper foil was etched and then the resist was removed to form a circuit, thereby forming a metal-based circuit board.

A solder paste ("M705" manufactured by henya chemical company) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSWO 36 AT" manufactured by riyaku company) was mounted by reflow soldering. Then, the metal base circuit board was fixed to a U-shaped case with an adhesive tape (F-9469 PC, manufactured by sumitomo 3M) having a thickness of 125 μ M on the side where the LED was not mounted, to obtain an LED light source unit.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 12.5V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the temperature of the LED was 65 ℃.

Comparative example 4-2

An insulating layer was formed on a copper foil having a thickness of 35 μm by combining alumina having a spherical coarse particle size of 75 μm or less in maximum particle size and having an average particle size of 21 μm and a sodium ion concentration of 10ppm (CB-A20 manufactured by Showa Denko K.K.: AKP-15) with alumina having a spherical fine particle size of 0.7 μm and a sodium ion concentration of 8ppm (AKP-15 manufactured by Sumitomo chemical Co., Ltd.) in such a manner that 50% by volume of the spherical coarse particle size (spherical coarse particle size) in the insulating layer was achieved (spherical coarse particle size: AKP-15) with respect to 100 parts by mass of an epoxy resin composed of a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 207 ("EXA-7015" manufactured by Dainippon ink Co., Ltd.) and a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 1200 ("YL-7170" manufactured by Nippon epoxy resin Co., Ltd.) containing 48 parts by mass of polyoxypropylene diamine ("D-400" and "2000" manufactured by ハルツマン Co., Ltd.) as a And spherical fine particles in a mass ratio of 7: 3) was added, and the thickness after curing was 100 μm. Then, a copper foil having a thickness of 35 μm was bonded, and the insulating layer was thermally cured by heating, whereby a metal base substrate was obtained in which the chloride ion concentration of the entire thermosetting resin in the insulating layer was 300ppm or less and the sodium ion concentration of the entire inorganic filler in the insulating layer was 50ppm or less.

The metal base circuit board is produced by forming a mask with a resist at a predetermined position, etching the copper foil, and then removing the resist to form a circuit.

A solder paste ("M705" manufactured by henya chemical company) was applied by screen printing to a predetermined position of a conductor circuit of a metal base circuit board, and an LED ("NFSWO 36 AT" manufactured by riyaku company) was mounted by reflow soldering. Then, the metal base circuit board was fixed to a U-shaped case with an adhesive tape (F-9469 PC, manufactured by sumitomo 3M) having a thickness of 125 μ M on the side where the LED was not mounted, to obtain an LED light source unit.

In an environment with a temperature of 23 ℃ and a humidity of 30%, a stable power supply was connected to the obtained LED light source unit, and the LED was turned on by a current of 450 mA. The voltage at this time was 11.2V. The temperature of the LED to be lit was measured by a thermocouple, and as a result, the LED temperature was 55 ℃.

Possibility of industrial utilization

The metal base circuit board of the present invention has heat dissipation properties and electrical insulation properties, and can be easily bent at room temperature even in a state where an electrical component such as a semiconductor element or an impedance chip, which requires heat dissipation, is mounted, so that it is possible to realize miniaturization and thinning of an electronic device in which a high heat generating electronic component is mounted, which have been difficult to realize in the past.

That is, the metal base circuit board of the present invention can be used in various fields of application, for example, in the application of an LED light source unit having characteristics such that the bending property is secured by attaching a coating layer and applying slit processing to a desired position, or a layer having magnetic loss or a layer having dielectric loss is formed, in a hybrid integrated circuit which is in contact with a case having a complicated shape or a heat radiating member, and that the temperature rise of an LED is small by efficiently radiating heat generated from an LED light source to the back surface side of a substrate, the decrease in the light emitting efficiency of the LED is suppressed, the luminance is high, and the lifetime is long.

In addition, the entire contents of the specification, claims, drawings and abstract of Japanese patent application No. 2005-120891 filed on 4/19/2005, Japanese patent application No. 2006-013289 filed on 1/23/2006, Japanese patent application No. 2006-030024 filed on 2/7/2006 and Japanese patent application No. 2006-87688 filed on 3/28/2006 are cited herein as disclosures of the present specification.

Claims (24)

1. A metal-based circuit board comprising an insulating layer and a conductor circuit or a metal foil laminated in an alternating manner, wherein the conductor circuit or the metal foil has a thickness of 5 to 450 [ mu ] m, the insulating layer is formed from a cured product of a resin composition containing an inorganic filler and a thermosetting resin, the insulating layer has a thickness of 9 to 300 [ mu ] m, and the thermosetting resin contains 40 mass% or less of a linear epoxy resin having an epoxy equivalent of 800 to 4000.

2. Gold according to claim 1The substrate is characterized in that at least 1 of the through holes for electrically connecting the conductor circuit or the metal foil is 0.0078mm²The above.

3. The metal-based circuit board according to claim 1 or 2, wherein the insulating layer has a thermal conductivity of 1 to 4W/mK.

4. The metal-based circuit board of claim 1, wherein the insulating layer has a glass transition temperature of 0 to 40 ℃.

5. The metal base circuit board according to claim 1, wherein the insulating layer is a cured product of a resin composition containing 25 to 60 vol% of a thermosetting resin and the balance of an inorganic filler having a sodium ion concentration of 500ppm or less, and the inorganic filler is composed of coarse spherical particles having an average particle diameter of 5 to 40 μm and a maximum particle diameter of 75 μm or less and fine spherical particles having an average particle diameter of 0.3 to 3.0 μm.

6. The metal-based circuit board according to claim 1, wherein the thermosetting resin contains a hydrogenated bisphenol F-type and/or A-type epoxy resin.

7. The metal-based circuit board according to claim 6, wherein the thermosetting resin contains a polyoxyalkylene polyamine as a curing agent.

8. The metal-based circuit board according to claim 6, wherein the chloride ion concentration in the thermosetting resin is 500ppm or less.

9. The metal-based circuit board according to claim 1, wherein when the circuit board is bent at an arbitrary position at a radius of curvature of 1 to 5mm by 90 ° or more, the withstand voltage between the layers of the conductor circuit or the metal foil is 1.0kV or more.

10. The metal base circuit board according to claim 1, wherein the metal foil is provided with a conductor circuit through an insulating layer and a coating layer having a thickness of 5 μm to 25 μm, and wherein a gap formed by removing at least a part of the coating layer is formed in a portion where the conductor circuit is not provided.

11. The metal base circuit board according to claim 10, wherein the slit is formed to have a length of 50% to 95% with respect to the bent portion.

12. The metal base circuit board according to claim 10, wherein the thickness of the coating layer is 5 μm to 25 μm.

13. The metal base circuit board according to claim 10, wherein the slit portion is bent.

14. The metal base circuit board according to claim 10, wherein the surface of the insulating layer is bent at 90 ° or more with a radius of curvature of 0.1 to 0.5 mm.

15. The metal base circuit board according to claim 10, wherein a layer having a magnetic loss or a layer having a dielectric loss is laminated on a surface of the coating layer.

16. The metal base circuit board according to claim 15, wherein the layer having magnetic loss is formed of a magnetic material having an aspect ratio of 2 or more and an organic binder, the content of the magnetic material is 30 to 70 vol%, and the thickness of the layer having magnetic loss is 3 to 50 μm.

17. The metal of claim 15The base circuit board is characterized in that the layer with dielectric loss has a specific surface area of 20-110 m²The carbon powder is 5-60 vol%, and the thickness of the layer with dielectric loss is 3-50 μm.

18. A hybrid integrated circuit using the metal base circuit board according to any one of 1 to 9.

An LED, wherein at least 1 LED is electrically connected to any one of 10 to 17 of the metal-based circuit boards.

An LED light source unit, wherein the metal base circuit board of any one of 1 to 17 is disposed on a surface of a case with an adhesive tape, and 1 or more light emitting diodes are mounted on a conductor circuit of the metal base circuit board.

21. The LED light source unit according to claim 20, wherein the adhesive tape has a thermal conductivity of 1 to 2W/mK and a thickness of 50 to 150 μm.

22. The LED light source unit of claim 20, wherein the adhesive tape comprises a polymer containing acrylic acid and/or methacrylic acid.

23. The LED light source unit of claim 20, wherein the adhesive tape contains 40 to 80 vol% of a thermally conductive electrical insulating agent.

24. The LED light source unit according to claim 23, wherein the thermally conductive electrical insulating agent has a maximum particle diameter of 45 μm or less and an average particle diameter of 0.5 to 30 μm.