TWI502005B - Light-reflective film, light-reflective laminate, and light-reflective circuit board - Google Patents

Description

Light reflective film, light reflective laminate, and light reflective circuit substrate [related application]

The present invention claims the priority of Japanese Patent Application No. 2010-071758, filed on Jan. 26, 2010, the entire content of which is hereby incorporated by reference.

The present invention relates to a mounting substrate suitable for use as a light-emitting element such as a white LED, a light-reflective film excellent in light reflectivity, and a light-reflective laminate and a light-reflective circuit substrate using the same.

In recent years, LEDs that can greatly reduce power consumption, such as electric bulbs and fluorescent lamps, have attracted attention. However, since high-output power is required for a light-emitting element such as an LED, a heat-resistant countermeasure is required for a substrate for use with an LED.

For example, an electronically mounted substrate formed by a light-reflective thermally conductive resin composition is disclosed in the above-mentioned Japanese Patent Laid-Open Publication No. 2008-169513. The light-reflective thermally conductive filler is laminated on the wiring pattern of the electronic component substrate via the electrically insulating layer and/or the electrically insulating adhesive layer, and the light-reflective thermally conductive resin composition is coated with a specific carbon fiber filler. A light-reflective layer of a light-reflective heat-conductive resin layer and a binder resin.

In the case of the electronic mounting substrate, by forming a light-reflective heat-conductive resin layer by mixing a specific filler with a resin composition of the binder resin, both light reflectivity and thermal conductivity of the surface of the mounting substrate can be improved.

[Previous Technical Literature] (Patent Literature)

Patent Document 1: Japanese Patent Laid-Open Publication No. 2008-169513

However, in the case of the electronically mounted substrate of Patent Document 1, since the carbon fiber of the laminated light-reflecting layer is used as a special light-reflective filler, the process is complicated and high in cost. Further, when the substrate of the light-reflective filler as described above is used, since the thermal expansion coefficient of the light-reflective filler and the adhesive resin are different, it is repeatedly exposed to high heat in an ON, OFF (on, off) operation such as a light-emitting element. In the case of the case, there is a concern that cracks occur in the binder resin.

Therefore, an object of an embodiment of the present invention is to provide a light-reflective film, a light-reflective laminate, and a light-reflective circuit substrate which can achieve excellent light reflectivity without using a light-reflective filler.

Another object of the present invention is to provide a light-reflective film, a light-reflective laminate, and a light-reflective circuit board which are excellent in heat resistance and excellent in light reflectivity.

Another object of the present invention is to provide a light-reflective film, a light-reflective laminate, and a light-reflective circuit board which are excellent in heat dissipation and excellent in light reflectivity.

The inventors of the present invention have found out through intensive studies to achieve the above objectives: (1) If the liquid crystal polymer film obtained by a specific molding method is used, the number of crystal domains can be controlled in the thickness direction of the film; (2) the light incident on the film from the incident surface is incident upon When the non-crystal matrix is carried out toward the crystal domain, it is found that reflection occurs at the interface between the crystal domain and the amorphous matrix; and, (3) as a result, when the number of crystal domains increases toward the thickness direction, The inside of the film can increase the ratio of the light reflected toward the incident surface of the film at the interface between the crystal domain and the amorphous matrix; (4) at the same time, it is found that the light transmitted through the exit surface relative to the incident surface of the film can be reduced. And (5) by reflecting the light in the crystal domain, thereby finding that the reflectance of the entire film can be improved; and, further, (6) by using a liquid crystal polymer having light reflectance as described above The film is bonded to the conductor layer or the circuit board layer while maintaining the light reflectivity, and it has been found that a laminate or a circuit board having excellent light reflectivity can be formed, and the present invention has finally been achieved.

That is, an embodiment of the present invention is a light-reflective laminate which is composed of at least a light-reflective film and a conductor layer or a circuit board layer bonded to at least one surface of the light-reflective film via an adhesive layer. . The light-reflective film is a thermoplastic liquid crystal polymer film in which a crystal domain exists in an amorphous matrix, and the crystal domain has 8 to 40 films per 10 μm in the thickness direction of the film. The film preferably has a light reflectance of, for example, 60% or more for a wavelength of 470 nm.

Further, the aforementioned thermoplastic liquid crystal polymer may be a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine. The foregoing film has heat resistance derived from a polymer, and for example, the film may have a melting point of about 250 ° C to 360 ° C.

The light-reflective laminate may have, for example, a light reflectance of 60% or more for a wavelength of 470 nm, and/or a thermal conductivity of 1 W/m for a planar direction. K or more.

Further, another embodiment of the present invention also includes a light-reflective circuit substrate which is formed by circuit-processing the light-reflective laminated body, and the light-reflective circuit substrate is preferably used by, for example, mounting a light-emitting element.

Furthermore, another embodiment of the present invention includes a method of producing a light-reflective laminate, which is a method of producing a light-reflective laminate by layering a light-reflective film, a conductor layer or a circuit board layer, and the manufacturing method includes: a bonding step of bonding an adhesive-coated surface of the light-reflective film to a conductor layer or a circuit board layer using at least one surface of the light-reflective film; the light-reflective film is made of a thermoplastic liquid crystal polymer film In the thermoplastic liquid crystal polymer film which is bonded to the conductor layer or the circuit board layer, a crystal domain exists in the amorphous matrix, and the crystal domain exists in the thickness direction of the film in the range of 8 to 40 per 10 μm.

In the bonding step of the manufacturing method, the light reflective film and the conductor layer or the circuit substrate layer may be heated at a temperature lower than the melting point of the light reflective film to be pressed or pressed without heating.

Further, another embodiment mode of the present invention also includes a light-reflective film for bonding to a conductor layer or a circuit substrate layer via an adhesive layer to form a light-reflective laminate, the light-reflective film being The thermoplastic liquid crystal polymer film is composed of a crystal domain in an amorphous matrix, and the crystal domain is present in an amount of 8 to 40 per 10 μm in the thickness direction of the film.

The light reflective film as described above may have a light reflectance of 60% or more for a wavelength of 470 nm, and/or a thermal conductivity of 0.8 W/m in a planar direction of the light reflective film. K or more.

Furthermore, another embodiment mode of the present invention also includes a circuit material which is composed of a light reflective film which is composed of a thermoplastic liquid crystal polymer film, and the thermoplastic liquid crystal polymer film is The crystal domain exists in the amorphous matrix, and the crystal domain exists in the thickness direction of the film in the range of 8 to 40 per 10 μm.

Furthermore, another embodiment of the present invention also includes a method for applying a light reflective film to a light reflective laminate, the method comprising bonding a conductor layer or a circuit substrate layer on at least one side of the light reflective film. a step of forming a light-reflective laminate, the light-reflective film being composed of a thermoplastic liquid crystal polymer film, and In the light-reflective laminate, the thermoplastic liquid crystal polymer film has a crystal domain in the amorphous matrix, and the crystal domain exists in the thickness direction of the film in the range of 8 to 40 per 10 μm.

In the light-reflective film and the light-reflective laminate of the present invention, since a plurality of crystal domains are provided in the film, the light incident on the film can be reflected from the interface between the crystal domain and the amorphous substrate, thereby improving the reflectance of the entire film.

Further, since a specific liquid crystal polymer is used, not only the melting point of the film but also the heat dissipation property can be improved, and even when it is used as a circuit board of a circuit board, particularly a light-emitting element such as an LED (Light Emitting Diode), Effectively suppressing the decrease in film properties due to heat.

Further, since the light-reflective substrate of the present invention is formed of a specific light-reflective film, light reflectivity can be obtained from the polymer material constituting the substrate even when the light-reflecting layer is not provided. Excellent heat resistance and/or heat dissipation. Therefore, it can be used as a mounting substrate such as a light-emitting element requiring high output power.

The invention may be more clearly understood from the following description of the preferred embodiments of the drawings. However, the mode of implementation and the drawings are for illustrative purposes only and should not be used as limiting the scope of the invention. The scope of the present invention is determined by the scope of the claims in this specification.

[Embodiment of the Invention]

The light reflective film of the present invention is composed of a thermoplastic liquid crystal polymer having a crystal domain present in an amorphous matrix.

(thermoplastic liquid crystal polymer)

The thermoplastic liquid crystal polymer is composed of a liquid crystalline polymer (or a polymer capable of forming an optically anisotropic molten phase) which can be melt-molded, as long as it is a liquid crystalline polymer which can be melt-molded. In the case of the material, the chemical composition is not particularly limited, and examples thereof include a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine having a guanamine bond introduced thereto.

Further, the thermoplastic liquid crystal polymer may further contain a ruthenium bond, a carbonate bond, a carbodiimide bond or an isomeric cyanate bond in an aromatic polyester or an aromatic polyester guanamine. A polymer derived from a bond of an isocyanate or the like.

Specific examples of the thermoplastic liquid crystal polymer which can be used in the present invention are exemplified by the compounds exemplified below which can be classified into (1) to (4) and the conventional thermoplastic liquid crystal polyesters and thermoplastics which can be derived from the derivatives thereof. Liquid crystal polyester decylamine. However, if a polymer which can form an optically anisotropic molten phase is to be formed, it is needless to say that a combination of various raw material compounds should have an appropriate range.

(1) Aromatic or aliphatic dihydroxy compounds (for representative examples, see Table 1)

(2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

(3) Aromatic hydroxycarboxylic acid (for representative examples, see Table 3)

(4) Aromatic diamine, aromatic hydroxylamine or aromatic aminocarboxylic acid (for representative examples, see Table 4)

Representative examples of the liquid crystal polymer which can be obtained by such a raw material compound include a copolymer having a structural unit as shown in Tables 5 and 6.

Among these copolymers, a polymer containing at least p-hydroxybenzoic acid and/or 6-hydroxy-2-naphthoic acid as a repeating unit is preferred, and it is particularly preferred that: (i) contains p-hydroxybenzoic acid and 6-hydroxyl group. a polymer of a repeating unit of -2-naphthoic acid; (ii) comprising at least one aromatic hydroxycarboxylic acid selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, selected from the group consisting of 4, At least one aromatic diol in the group consisting of 4'-dihydroxybiphenyl and hydroquinone, and a group selected from the group consisting of terephthalic acid, isophthalic acid and 2,6-naphthalene dicarboxylic acid a polymer of at least one repeating unit of an aromatic dicarboxylic acid.

For example, in the case of the polymer of (i), that is, in the case where the thermoplastic liquid crystal polymer is a repeating unit containing at least p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, in the liquid crystal polymer, the repeating unit The molar ratio (A)/(B) of the p-hydroxybenzoic acid of (A) to the 6-hydroxy-2-naphthoic acid of the repeating unit (B), preferably (A) / (B) = about 10/90 Up to 90/10, more preferably (A) / (B) = about 50/50 to 85/15, still more preferably (A) / (B) = about 60/40 to 80/20.

Further, in the case of the polymer of (ii), that is, at least one aromatic hydroxycarboxylic acid (C) selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, selected from At least one aromatic diol (D) in the group consisting of 4,4'-dihydroxybiphenyl and hydroquinone, and selected from the group consisting of terephthalic acid, isophthalic acid and 2,6-naphthalene dicarboxylic acid At least one aromatic dicarboxylic acid (E) in the group formed, in the liquid crystal polymer, the molar ratio of each repeating unit may be an aromatic hydroxycarboxylic acid (C): the aforementioned aromatic diol (D) : the aforementioned aromatic dicarboxylic acid (E) = about 30 to 80: 35 to 10: 35 to 10, more preferably (C): (D): (E) = about 35 to 75: 32.5 to 12.5: 32.5 to 12.5, further preferably (C): (D): (E) = about 40 to 70:30 to 15:30 to 15.

Further, the molar structure derived from the repeating structural unit of the aromatic dicarboxylic acid and the repeating structural unit derived from the aromatic diol is preferably (D) / (E) = 95 / 100 to 100 / 95. If it is not in this range, the degree of polymerization cannot be increased, and the mechanical strength tends to decrease.

In the present invention, the "optical anisotropy at the time of melting" is, for example, a sample can be placed on a high-temperature stage, heated and heated in a nitrogen atmosphere, and the transmitted light of the sample can be observed and identified.

The preferred thermoplastic liquid crystal polymer has a melting point (hereinafter, referred to as "Mp") of from 250 to 360 ° C, more preferably from 260 to 350 ° C. Further, Mp can be measured by measuring the temperature at which the main endothermic peak is exhibited by using a differential scanning calorimeter.

In the aforementioned thermoplastic liquid crystal polymer, polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, poly can be added within a range that does not impair the efficacy of the present invention. Thermoplastic polymers such as carbonates, polyarylates, polyamines, polyphenylene sulfides, polyester ether ketones, fluororesins, various additives, fillers, and the like.

The thermoplastic liquid crystal polymer film which can be used in the present invention can be obtained by extrusion molding a thermoplastic liquid crystal polymer. Any extrusion molding method can be used as long as it can control the crystal domain structure of the thermoplastic liquid crystal polymer, and for example, the crystal domain structure can be controlled by a blow molding method.

In the case of the blow molding method, the cylindrical sheet which is melt-extruded through the annular die has a specific draw ratio (equivalent to the MD (longitudinal direction) stretching ratio) and a blow ratio (blow). Ratio) (corresponding to the stretching ratio in the TD (width direction) direction), the stretching ratio, the stretching ratio in the MD direction, and the stretching ratio (or the stretching ratio) in the TD direction are extended in total. The magnification (that is, the draw ratio × the blow ratio) may be, for example, 5 times or more, preferably 10 times or more, more preferably 13 times or more. Further, the upper limit of the total stretching ratio may be appropriately set depending on the thickness of the film or the like, and for example, the total stretching ratio may be 30 times or less.

Further, the mold shear rate (sometimes referred to simply as "shear rate") of the thermoplastic polymer in the mold region when melted and extruded by the mold is selected in accordance with the thickness of the film to be formed, etc., 300 seconds ^-1 The above (e.g., 350 to 5000 sec ^-1 ) is preferably selected from about 400 to 4000 sec ^-1 .

In the present invention, a liquid crystal polymer film having a specific crystal domain structure can be formed by extrusion molding as described above.

Further, a conventional or conventional heat treatment may be applied to the film after extrusion molding, but it is preferably carried out within a range that does not cause a large change in the domain structure due to heat treatment. If the number of crystal domains is less than the range specified by the present invention, heat treatment may not necessarily be applied.

Further, the thermoplastic liquid crystal polymer film may be stretched as needed after extrusion molding as needed. The extension method itself is either a conventional biaxial extension or a uniaxial extension, and since it is easier to control the molecular orientation, it is preferably a biaxial extension. Further, the extension may be a conventional uniaxial stretching machine, a simultaneous biaxial stretching machine, or a sequential biaxial stretching machine or the like.

(light reflective film)

In the case of the light-reflective film of the present invention comprising the thermoplastic liquid crystal polymer film, a crystalline domain exists in the amorphous matrix, and the number of crystal domains is 8 to 40 per 10 μm in the thickness direction of the film. It is preferably from 10 to 35, more preferably from about 12 to 30. Further, the number of the crystal domains is a value measured by the method described in the examples below. Further, the film is preferably used for bonding to a conductor layer or a circuit board layer via an adhesive layer to form a light-reflective laminate.

In the light reflective film of the present invention, when the light incident on the film collides with the crystal domain inside the film, the boundary between the amorphous matrix and the crystalline domain Reflections will occur on the surface. If there are many crystal domains inside the film, the proportion of light transmitted through the film can be reduced, and the proportion of light reflected by the crystal domain can be further increased. Thereby, although the effect of the external reflection layer is not negated, even in the case where a reflection layer such as a metal thin film is not applied, the film as a whole can achieve high reflectance.

In particular, in the light-reflective film of the present invention, by imparting reflectivity to the film by controlling the crystal domain structure, the light-reflective filler or the light-scattering filler added to the film in order to improve light reflectivity is not used. The film can be imparted with high light reflectivity.

The shape of the crystal domain is not particularly limited as long as it can reflect light at the interface between the crystal domain and the amorphous matrix, and various shapes such as a spherical shape, a cylindrical shape, a spindle shape, a polygonal pyramid system, a rectangular shape, and an amorphous shape are exemplified, but From the viewpoint of increasing the reflectance at the interface between the crystal domain and the amorphous matrix, the shape of the domain is preferably flat.

For example, in the thickness direction cross section of the film, the crystal region preferably has an aspect ratio (long axis/minor axis) of the major axis and the minor axis of the domain, for example, 5 or more, preferably 10 or more, more preferably 15 or more. Further, the upper limit is not particularly limited, and for example, the aspect ratio may be 40 or less. Further, the crystal domain can be calculated in accordance with the method disclosed in the examples described later.

Further, when the crystal domain is flat, the major axis of each crystal domain is preferably substantially parallel to the plane of the film. Further, the term "substantially parallel" means that the intersection angle of the film plane and the long axis is, for example, within ±30°.

In the light reflective film of the present invention, for example, the light reflectance at a wavelength of 470 nm may be 60% or more, preferably 65% or more, more preferably It is 70% or more. Here, the "light reflectance" as used herein is a value measured by the method described in the examples below.

Further, in the case of the light-reflective film of the present invention, the heat resistance to high temperature is high due to the properties of the liquid crystal polymer, and the melting point (that is, the melting point of the liquid crystal polymer film) may be 250 ° C or higher (for example, about 250). Up to 350 ° C), preferably 260 ° C or higher (for example, about 260 to 340 ° C), more preferably 270 ° C or higher (for example, about 270 to 330 ° C). Further, the upper limit of the melting point is usually about 360 ° C.

Further, from the viewpoint of imparting heat dissipation to a film or a substrate, the light-reflective film of the present invention has a thermal conductivity in a planar direction of the film of 0.8 W/mK or more (for example, about 1 to 30 W/mK), preferably 1 W/. More than mK. Further, the thermal conductivity is a value measured by the method described in the examples below.

(circuit material)

The circuit material of the present invention is composed of a light reflective film. Further, the circuit material may be composed of a light reflective film and an adhesive layer formed on at least one surface of the light reflective film. In this case, the light-reflective film can be used as a circuit material in various modes. For example, a light-reflective film can be used as a dielectric layer on a circuit board or a cover film for a circuit board. Further, the adhesive layer can be formed by using various adhesives in the item of the light-reflective laminate described later.

(light reflective laminate)

The light-reflective laminated system of the present invention comprises at least the light-reflective film and a conductor layer or a circuit board layer joined to each other via at least one surface of the light-reflective film via an adhesive layer.

The light-reflective laminate of the present invention is characterized in that it is a thermoplastic liquid crystal polymer film as a constituent element of the light-reflective film. That is, in the light-reflective laminate, the light-reflective film is in an amorphous matrix of the thermoplastic liquid crystal polymer film, and the crystal domains are present in an amount of 8 to 40 per 10 μm in the thickness direction of the film. Therefore, the light-reflective film of the light-reflective laminate may have one or more of the above various physical properties.

These light-reflective laminated systems are produced by bonding a conductor layer or a circuit board layer to at least one surface of the light-reflective film via an adhesive layer.

The conductor layer is preferably made of a metal capable of forming a circuit, and examples thereof include metal foils of gold, silver, copper, nickel, aluminum or alloy metals thereof. Among these metals, copper is preferably used. The thickness of the metal foil may also be, for example, about 5 to 50 μm, preferably 8 to 40 μm.

The circuit board layer may be formed of a dielectric or an insulator having a circuit formed on at least one surface, and examples of the dielectric or insulator include ceramics, epoxy resins, polyimides, liquid crystal polymers, and the like. a film or sheet.

In the bonding step, various bonding methods can be carried out as long as the light reflectivity of the light-reflective film can be maintained, and the light-reflective film and the conductor layer or the circuit board layer are usually pressed by an adhesive.

For example, the adhesive may be applied to the coated surface of the light-reflective film by gravure coating, knife coating, roll coating, brush coating, spray coating, or the like, and then the conductor layer or the circuit board layer may be in contact with the coated surface. The press pressurization light reflective film is integrated with both the conductor layer or the circuit board layer.

Further, when a film-like hot-melt adhesive is used for the light-reflective film, the film-like hot-melt adhesive can be interposed between the conductor layer or the circuit board layer and the light-reflective film, and the press machine can be used. The pressurized light reflective film is integrated with both the conductor layer and the circuit board layer.

When the pressure is applied, from the viewpoint of maintaining the light reflectivity of the light-reflective film, if it is heated to a temperature higher than the melting point of the light-reflective film, it tends to be inferior. The pressing is preferably carried out under non-heating, and the heating temperature must be lower than the melting point of the light-reflective film even if it is subjected to hot pressing. If the melting point of the light-reflecting film is Mp, it is preferably Mp-10. Below °C, more preferably below Mp-20 °C.

As the adhesive, an acrylate-based, phenol-based or epoxy-based thermosetting adhesive can be used, or a film made of a thermoplastic resin film (for example, a thermoplastic polyester film or a thermoplastic liquid crystal polymer film) can be used. Hot melt adhesive.

Further, the melting point of the film-like hot-melt adhesive can be selected in accordance with the heating temperature. For example, when the melting point of the light-reflective film is Mp, it is preferably Mp-20 ° C or lower, preferably Mp -30 ° C or lower. .

The light-reflective laminate may be a unit including at least one conductor layer or a circuit board layer and one layer of a light-reflective film, and the light-reflective laminate may be formed by alternately stacking at least one layer. A multi-layer laminate of a light reflective film and at least one conductor layer or circuit substrate layer.

The light-reflective laminate of the present invention may have a light reflectance of, for example, a wavelength of 470 nm of 60% or more, preferably 65% or more, more preferably More than 70%. Here, the "light reflectance" as used herein is a value measured by the method described in the examples below.

Further, the light-reflective laminate of the present invention is excellent in heat dissipation, and may have a thermal conductivity in the planar direction of 1 W/mK or more (for example, about 1 to 30 W/mK), preferably 1.1 W/mK or more. Good is 1.2W/mK or more. Further, the thermal conductivity is a value measured by the method described in the examples below.

For example, the light-reflective laminate of the present invention may have a structure as shown in the following first to fifth embodiments as various embodiments. FIG. 1 is a view showing a light-reflective laminated body 10 including a light-reflective film 11 and a conductor layer 13 bonded to one surface of the light-reflective film 11 via an adhesive layer 12. In the embodiment mode of Fig. 1, the light reflective film 11 is used as a dielectric layer for the conductor layer 13.

2 is a view showing a light-reflective laminated body 20 including a light-reflective film 21 and a circuit board layer 24 joined to one surface of the light-reflective film 21 via an adhesive layer 22. In the embodiment mode of Fig. 1, the light reflective film 21 is used as a surface film for the circuit board layer 24.

3 is a view showing a light-reflective laminated body 30 including a light-reflective film 31, a first conductor layer 33 joined to one surface of the light-reflective film 31 via the first adhesive layer 32, and light reflection. The second conductor layer 36 joined to the other side of the thin film 31 via the second adhesive layer 35. In the embodiment mode of Fig. 3, the light reflective film 31 is used as a dielectric layer for the conductor layers 33, 36.

4 is a view showing a light-reflective laminated body 40 including a light-reflective film 41, a conductor layer 43 bonded to one surface of the light-reflective film 41 via the first adhesive layer 42, and a light-reflective film. The other side of the 41 is bonded to the circuit board layer 44 via the second adhesive layer 45. In the embodiment mode of Fig. 4, the light reflective film 41 is used as a dielectric layer for the conductor layer 43.

Fig. 5 is a view showing a light-reflective laminated body 50 including a first light-reflective film 51, a conductor layer 53 bonded to one surface of the light-reflective film 51 via a first adhesive layer 52, and light reflectivity. The circuit board layer 54 joined to the other surface of the film 51 via the second adhesive layer 55, and the second light reflectance bonded to the surface of the circuit board layer 54 facing the light reflective film 51 via the third adhesive layer 57 Film 58. In the embodiment shown in FIG. 5, the first light reflective film 51 is used as a dielectric layer for the conductor layer 53, and the second light reflective film 58 is used as a shield for the circuit substrate layer 54. membrane.

In addition, in all of the above-described embodiments, as long as the structure of the present invention including the light-reflective film, the conductor layer, or the circuit board layer is the smallest unit, other layers may be included as needed. The scope of the invention includes various modifications. Further, the adhesive layer may be unhardened or partially cured. Further, the circuit substrate layer may be uncured, locally hardened, or completely cured.

(light reflective circuit board)

The light-reflective circuit substrate of the present invention (hereinafter sometimes referred to as "light-reflective substrate") may be a single layer or a plurality of layers of two or more layers.

The light-reflective substrate is formed by forming a light-reflective laminated body from the above-described light-reflective film, and applying a circuit process to the light-reflective laminated body by a conventional or conventional method. Furthermore, the circuit processing is a method used to manufacture a general wiring board.

The light-reflective substrate may have any thickness as long as it can be used as a substrate, and includes a plate shape or a sheet shape of 5 mm or less. For example, the flexible substrate preferably has a thickness of 10 to 500 μm. More preferably, it is in the range of 15 to 200 μm.

Further, the substrate may be formed of a single layer of a light-reflective film, or a laminate of a plurality of sheets of a film having a thickness of 10 to 200 μm (for example, about 3 to 20 sheets, preferably about 5 to 15 sheets). Substrate.

The light-reflective substrate of the present invention has various physical properties (light reflectivity, radioactivity) derived from the light-reflective laminate. Therefore, for example, a circuit board which can be used for various electronic devices by utilizing light reflectivity can be used, and particularly, it can be used as a circuit board for mounting light-emitting elements such as various LEDs (particularly white LEDs) and laser diodes.

"Embodiment"

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited by the examples. Further, the examples and comparative examples below were measured for various physical properties by the following methods.

[melting point]

Obtained by observing the thermal behavior of the film using a differential scanning calorimeter (TA3000 manufactured by Mettler Co., Ltd.). That is, after the test film is completely melted at a temperature of 20 ° C /min, the endothermic peak which appears when the melt is rapidly cooled to 50 ° C at a rate of 50 ° C / min and then raised at a rate of 20 ° C / min. The position is recorded as the melting point of the film.

[mold shear rate]

The film shear rate experienced by the molten thermoplastic liquid crystal polymer in the mold region at the time of film formation of the blown film is defined as follows. In the formula, Q represents the resin discharge amount (mm ³ /second), R represents the mold diameter (mm), and d represents the mold slit interval (mm).

Mold shear rate (sec ^-1 ) = (6 × Q) / (π × R × d ² )

[Number and aspect ratio of crystal domains]

The film was immersed in ethylamine at room temperature for 4 hours, and the cut surface was observed in the thickness direction of the film by an electron microscope. On the photograph taken at 10,000 times, three straight lines were randomly drawn in the thickness direction, and the number of crystal domains intersecting each straight line was measured, and the average value of the thickness of the film per 10 μm was taken as the number of crystal domains.

Further, the aspect ratio (long axis/minor axis) of the crystal domain intersecting the straight line was measured, and the average value thereof was defined as the aspect ratio of the crystal domain of the film.

[light reflectivity]

The total reflectance (specular reflectance + diffuse reflectance) of the film or the light-reflective laminate in the wavelength region of 470 nm was measured using a spectrophotometer ("V-570" manufactured by JASCO Corporation).

〔Thermal conductivity〕

The measurement was carried out at a measurement temperature of 20 ° C using a laser flash thermal constant measuring device ("LF/TCMFA8510B" manufactured by Rigaku Corporation). Furthermore, the measurement of the planar direction is carried out with a dedicated attachment.

[thickness of film]

The thickness is a digital thickness meter (Mitutoyo Co., Ltd.), and the film (size: TD direction 50 cm × MD direction 3 metric) The measurement was performed at intervals of 1 cm in the TD direction, and the average value of 10 points arbitrarily selected from the center portion and the end portion was taken as the film thickness.

[Example 1]

A thermoplastic liquid crystal polymer having a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (mole ratio: 73/27) and a melting point of 280 ° C is heated and kneaded by a single screw extruder, and the diameter of the mold is An annular blown film mold of 33.5 mm and a die slit interval of 500 μm was melt-extruded at a die shear rate of 1000 sec ^-1 , and the elongation ratio (Dr) in the longitudinal direction was 2.9, and the lateral extension ratio (Bl) A film having a melting point of 280 ° C and a film thickness of 25 μm was obtained under the conditions of 6.2. A cross-sectional photograph of the obtained film is shown in Fig. 6, and its properties are shown in Table 1.

Further, a light reflective laminate was formed using the film in the following procedure. "JTC-18AM" (thickness: 18 μm) made of JX Nippon Mining & Metal Co., Ltd., and Nikaan Industrial Co., Ltd. "NIKAFLEX (registered trademark) SAFW" (thickness: 20 μm), and The light-reflective film was laminated under the conditions of a temperature of 160 ° C and a pressure of 2 MPa over 60 minutes to produce a light-reflective laminate (copper-clad laminate). The physical property evaluation sample was a film in which a copper foil was removed using a ferric chloride solution.

[Example 2]

A thermoplastic liquid crystal polymer having a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (mole ratio: 80/20) and a melting point of 325 ° C is heated and kneaded by a single screw extruder, and the diameter of the mold is A 33.5 mm annular blown film mold with a die slit spacing of 950 μm was melt extruded at a die shear rate of 500 sec ^{- 1} with a longitudinal extension ratio (Dr) of 2.9 and a lateral extension ratio (Bl). A film having a melting point of 325 ° C and a film thickness of 50 μm was obtained under the conditions of 6.2. A photograph of the cross section of the obtained film is shown in Fig. 7, and its properties are shown in Table 1.

Further, using this film, a light-reflective laminate was produced in the same manner as in Example 1.

[Example 3]

The glass fiber epoxy resin substrate FR-4 ("R-1766" (thickness: 1.6 mm) manufactured by Panasonic Electric Co., Ltd.) was processed into a specific circuit, and the adhesive was made using NIKAFLEX (registered by Nikkan Industrial Co., Ltd.). The trademark "SAFW" (thickness: 20 μm) was laminated on the light-reflective film obtained in Example 1 under the conditions of a temperature of 160 ° C and a pressure of 2 MPa for 60 minutes to produce a light-reflective laminate (surface film). Laminated circuit board).

[Comparative Example 1]

About 1 g of the same polymer material as in Example 1 was spread on a SUS plate, and the film was pressed at 300 ° C under a pressure of 4 MPa for 10 minutes to obtain a film having a film thickness of 50 μm. A photograph of the cross section of the obtained film is shown in Fig. 8, and its properties are shown in Table 1. Further, using this film, a light-reflective laminate was produced in the same manner as in Example 1.

[Comparative Example 2]

The "Vectra C950" manufactured by Polyplastics Co., Ltd. was melted in a single-screw extruder (screw diameter of 60 mm) from the T-die at the front end of the extruder (the length of the lip was 300 mm, and the lip gap was 1.0 mm and a mold temperature of 350 ° C) were extruded into a film form and cooled to obtain a liquid crystal polymer film having a thickness of 250 μm. On both sides of the liquid crystal polymer film, a porous polytetrafluoroethylene film having a thickness of 40 μm was heat-pressed at a temperature of 330 ° C (rolling speed of 2 m/min).

Next, the light-reflective laminated body obtained as described above was extended by a biaxial stretching machine. The extension condition at this time was that the stretching temperature was 350 ° C, the stretching ratio was 1.6 times in the MD direction, the TD direction was 3.2 times, and the stretching speed was 20%/second. Finally, the porous polytetrafluoroethylene film was peeled off from both sides of the liquid crystal polymer film to obtain a liquid crystal polymer film having a thickness of 50 μm. A cross-sectional photograph of the obtained film is shown in Fig. 9, and its properties are shown in Table 1. Further, using this film, a light-reflective laminate was produced in the same manner as in Example 1.

As shown in FIGS. 6 and 7 and Table 7, the light-reflective films of Examples 1 and 2 have a thickness cross section of the film, and the domains are substantially parallel to the film plane in a layered manner, and there are 10 or more layers due to the existence of the domain. , can improve the light reflectivity of the film.

The obtained film can exhibit high light reflectance even without using a light-scattering filler, and can suppress cracking due to the filler. Further, the obtained film has high thermal conductivity and excellent heat dissipation.

Further, in the case of the light-reflective laminates obtained in Examples 1 to 3, the number of domains in the thickness direction of the film does not change before the bonding step of the conductor layer or the circuit board layer. Therefore, when the light-reflective substrate is used as the light-reflective substrate of the substrate, the high-reflectivity and heat dissipation property of the light-reflective film can be imparted to the circuit substrate.

On the other hand, in the thermoplastic liquid crystal polymer films of Comparative Examples 1 and 2, since the number of domains existing in the thickness direction of the film was small, the ratio of transmitted light was increased, so that excellent light reflectivity could not be exhibited. Further, the thermal conductivity is also lower than the value of the embodiment, and is also inferior to the embodiment in terms of heat dissipation. Therefore, in the case of the light-reflective laminate and the circuit board obtained by using the film, light reflection from the film cannot be imparted to the circuit board.

[Industrial use possibility]

The light reflective film, the light reflective laminate, and the circuit material of the present invention are usable as electrical. The substrate material of the electronic product is particularly excellent in light reflectivity, and can be effectively used as a light-reflective substrate for mounting various light-emitting elements (such as LEDs such as white LEDs).

As described above, the preferred embodiments of the present invention have been described with reference to the drawings, and those skilled in the art can be easily modified and modified within the scope of the present disclosure. However, such changes and amendments shall fall within the scope of the invention as defined by the scope of the patent application in this case.

10‧‧‧Light reflective laminate

11‧‧‧Light reflective film

12‧‧‧ adhesive layer

13‧‧‧Electrical layer

20‧‧‧Light reflective laminate

21‧‧‧Light reflective film

22‧‧‧ adhesive layer

24‧‧‧Circuit board layer

30‧‧‧Light reflective laminate

31‧‧‧Light reflective film

32‧‧‧First adhesive layer

33‧‧‧First conductor layer

35‧‧‧Secondary adhesive layer

36‧‧‧Second conductor layer

40‧‧‧Light reflective laminate

41‧‧‧Light reflective film

42‧‧‧First adhesive layer

43‧‧‧Electrical layer

44‧‧‧Circuit board layer

45‧‧‧ adhesive layer

50‧‧‧Light reflective laminate

51‧‧‧Light reflective film

52‧‧‧First adhesive layer

53‧‧‧Electrical layer

54‧‧‧Circuit board layer

55‧‧‧Secondary adhesive layer

57‧‧‧ Third adhesive layer

58‧‧‧Light reflective film

Fig. 1 is a schematic cross-sectional view showing an embodiment of a light-reflective laminate of the present invention.

Fig. 2 is a schematic cross-sectional view showing another embodiment of the light-reflective laminate of the present invention.

Figure 3 is a view showing the light reflective laminate of the present invention. A schematic cross-sectional view of other embodiments.

Fig. 4 is a schematic cross-sectional view showing another embodiment of the light-reflective laminated body for explaining the present invention.

Fig. 5 is a schematic cross-sectional view showing another embodiment of the light-reflective laminate of the present invention.

Fig. 6 is an electron micrograph (10,000 magnifications) showing a cross section in the thickness direction of the light-reflective film produced in accordance with Example 1.

Fig. 7 is an electron micrograph (10,000 magnifications) showing a cross section in the thickness direction of the light-reflective film produced in Example 2.

Fig. 8 is an electron micrograph (10,000 magnifications) showing a cross section in the thickness direction of the liquid crystal polymer film obtained in Comparative Example 1.

Fig. 9 is an electron micrograph (10,000 magnifications) showing a cross section in the thickness direction of the liquid crystal polymer film obtained in Comparative Example 2.

10‧‧‧Light reflective laminate

11‧‧‧Light reflective film

12‧‧‧ adhesive layer

13‧‧‧Electrical layer

Claims (16)

A light-reflective laminate comprising at least a light-reflective film and a conductor layer or a circuit board layer bonded to at least one surface of the light-reflective film via an adhesive layer, wherein the light-reflective film is non-conductive a thermoplastic liquid crystal polymer film having a crystal domain in a crystal matrix; wherein the crystal field is in the film by an average of the number of crystal domains randomly intersecting the straight lines in the thickness direction of the film section There are 8 to 40 in the thickness direction per 10 μm, and the thermoplastic liquid crystal polymer film is composed of a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine. The light-reflective laminate of the first aspect of the invention, wherein the light-reflective film has a melting point of from 250 ° C to 360 ° C. The light-reflective laminate of the first aspect of the patent application has a light reflectance of 60% or more for a wavelength of 470 nm. The light-reflective laminated body according to any one of claims 1 to 3, wherein the thermal conductivity in the plane direction is 1 W/m. K or more. A light-reflective circuit board which is formed by circuit-processing a light-reflective laminated body according to any one of claims 1 to 4. A light-reflective circuit substrate according to claim 5, which is used for mounting a light-emitting element. A method for producing a light-reflective laminate, which comprises a method of producing a light-reflective laminate by layering a light-reflective film, a conductor layer or a circuit board layer, and comprising the steps of: a bonding step of bonding an adhesive-using surface of the light-reflective film to the conductor layer or the circuit board layer using at least one surface of the light-reflective film; the light-reflective film is made of a thermoplastic liquid crystal polymer film The thermoplastic liquid crystal polymer film is composed of a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine, and the thermoplastic liquid crystal polymer film after being bonded to the conductor layer or the circuit substrate layer exists in the amorphous matrix. a crystal domain, and an average of the number of crystal domains intersecting each of the straight lines in the thickness direction of the film in the thickness direction, and the crystal domains are 8 to 40 per 10 μm in the thickness direction of the film. . The manufacturing method of claim 7, wherein in the bonding step, the light reflective film and the conductor layer or the circuit substrate layer are heated and pressed at a temperature lower than a melting point of the light reflective film. The manufacturing method of claim 7, wherein in the bonding step, the light reflective film and the conductor layer or the circuit substrate layer are pressed without heating. A light-reflective film for bonding a conductor layer or a circuit board layer via an adhesive layer to form a light-reflective laminate, the light-reflective film being composed of a thermoplastic liquid crystal polymer film, and the thermoplastic The liquid crystal polymer film is an average of the number of crystal domains in which a crystal domain exists in an amorphous matrix, and three straight lines are randomly drawn in the thickness direction of the film to intersect each line. The crystal domain is present in an amount of from 8 to 40 per 10 μm in the thickness direction of the film, and the thermoplastic liquid crystal polymer film is composed of a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine. The light-reflective film of claim 10, wherein the light-reflective film has a light reflectance of 60% or more with respect to a wavelength of 470 nm. The light-reflective film of claim 10, wherein the crystal domain is flat; the angle of intersection between the major axis of each crystal domain and the plane of the film is within ±30°. The light-reflective film of claim 10, wherein the aspect ratio (long axis/minor axis) of the major axis and the minor axis of the crystal domain is 5 or more and 40 or less in the thickness direction cross section of the film. . The light reflective film according to any one of claims 11 to 13, wherein the light reflective film has a thermal conductivity of 0.8 W/m in the plane direction. K or more. A circuit material which is composed of a light reflective film which is composed of a thermoplastic liquid crystal polymer film, and the thermoplastic liquid crystal polymer film is a crystalline domain in an amorphous matrix, and In the cross-section of the film, an average of the number of crystal domains intersecting each of the three straight lines and intersecting the respective straight lines in the thickness direction is 8 to 40 per 10 μm in the thickness direction of the film, and the thermoplastic liquid crystal is polymerized. The film is composed of a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine. A method for using a light-reflective film for a light-reflective laminate, comprising: forming a light-reflective laminate by bonding a conductor layer or a circuit board layer to at least one surface of the light-reflective film, the light The reflective film is composed of a thermoplastic liquid crystal polymer film composed of a thermoplastic liquid crystal polyester or a thermoplastic liquid crystal polyester decylamine, and in the light reflective laminate, the thermoplastic liquid crystal polymer The film has a crystal domain in the amorphous matrix, and is an average of the number of crystal domains intersecting each of the straight lines in the thickness direction of the film in the thickness direction, and the crystal field is in the thickness of the film. There are 8 to 40 directions per 10 μm.