JP2002324978A - Multilayer wiring board - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a multilayer wiring board that cannot satisfy the demands for higher wiring density and the requirements for solder heat resistance, insulation properties, high frequency transmission characteristics, and temperature cycle resistance. SOLUTION: A plurality of insulating layers 1 are laminated with a wiring conductor 2 made of metal foil interposed therebetween, and a through conductor formed in the insulating layer 1 between wiring conductors 2 located vertically above and below the insulating layer 1. Multilayer wiring board 4 electrically connected via
And the insulating layer 1 is formed on the upper and lower surfaces of the liquid crystal polymer layer 5,
60 to 80, depending on the polyphenylene ether organic material
A first layer 6a composed of a volume% of inorganic insulating powder;
2nd layer 6b formed by bonding ~ 60% by volume of inorganic insulating powder
And a third layer 6c formed by bonding 20 to 40% by volume of inorganic insulating powder to form a coating layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer wiring board used for electronic devices such as various AV devices, home appliances, communication devices, computers and their peripheral devices, and more particularly to a liquid crystal device having a part of an insulating layer. The present invention relates to a multilayer wiring board using a polymer layer.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board for forming a hybrid integrated circuit in which a predetermined electronic circuit is formed by mounting a large number of active parts such as semiconductor elements and passive parts such as capacitance elements and resistance elements is usually used. Through holes are formed up and down by drilling in an insulating layer made of glass cloth impregnated with epoxy resin,
It is formed by laminating a large number of wiring boards each having a plurality of wiring conductors formed inside the through holes and on the surface of the insulating layer.

In general, current electronic devices are required to be small, thin, lightweight, high-performance, high-function, high-quality, and high-reliability, as typified by mobile communication devices. Electronic components such as hybrid integrated circuits mounted on
In order to respond to such demands for higher densities, multilayer wiring boards that make up electronic components are also required to have finer wiring conductors and thinner insulating layers.
It is becoming necessary to miniaturize the through holes. For this reason, in recent years, laser processing that can perform finer processing than drill processing has been used in order to make through holes finer.

However, an insulating layer formed by impregnating a glass cloth with an epoxy resin has a limitation in miniaturizing a through-hole because it is difficult to pierce the glass cloth with a laser. There is a problem that it is difficult to form a through-hole having a uniform diameter due to the uneven thickness.

In order to solve such a problem, an insulating base made by impregnating a nonwoven fabric made of aramid resin fiber with an epoxy resin or an insulating base made by applying an epoxy-based adhesive to a polyimide film are used. A multilayer wiring board used for an insulating layer has been proposed.

However, an insulating substrate using an aramid nonwoven fabric or a polyimide film has high hygroscopicity. If solder reflow is performed in a state of absorbing moisture, the moisture absorbed by the heat of the solder reflow vaporizes to generate gas, and an insulating interlayer is generated. With the problem of peeling.

In order to solve such problems, use of a liquid crystal polymer as a material for an insulating layer of a multilayer wiring board has been studied. The layer composed of the liquid crystal polymer is composed of rigid molecules and has a structure in which molecules are regularly arranged to some extent, and has a strong intermolecular force.
Shows high heat resistance, high elastic modulus, high dimensional stability, low moisture absorption,
There is no need to use a reinforcing material such as glass cloth, and it has features of being excellent in fine workability. Furthermore, even in a high-frequency region, it has a characteristic that it has a low dielectric constant and a low dielectric loss tangent, and has excellent high-frequency characteristics.

[0008] Utilizing the characteristics of such a liquid crystal polymer,
Japanese Patent Application Laid-Open No. 8-97565 discloses a multi-layer printing method in which an adhesive layer containing a second liquid crystal polymer having a melting point lower than that of the first liquid crystal polymer is inserted between circuit layers containing the first liquid crystal polymer. A circuit board has been proposed.
JP-A-2000-269616 proposes a high-frequency circuit board in which a thermoplastic liquid crystal polymer film and a metal foil are bonded using an epoxy-based adhesive.

[0009] However, in the multilayer printed circuit board proposed in Japanese Patent Application Laid-Open No. 8-97565, the liquid crystal polymer molecules are rigid when the circuit layers are bonded by thermocompression bonding by inserting an adhesive layer containing a liquid crystal polymer therebetween. It is difficult to move, and it is not possible to enter the fine recesses on the surface of the circuit layer, as a result, it is not possible to exert a sufficient anchor effect, the adhesion between the circuit layer and the adhesive layer is poor, There is a problem that insulation failure occurs.

The high-frequency circuit board proposed in Japanese Patent Application Laid-Open No. 2000-269616 has a small thickness caused by pressure during lamination since the dielectric constant of an epoxy-based adhesive is significantly different from that of a liquid crystal polymer. Due to the variation, there is a problem that transmission characteristics are degraded in a high frequency region, particularly in a frequency region of 100 MHz or higher.

In order to solve such a problem, the applicant of the present invention disclosed in Japanese Patent Application No. 2001-53834 a plurality of insulating layers formed by forming a coating layer made of a polyphenylene ether organic material on the upper and lower surfaces of a liquid crystal polymer layer. A laminated multilayer wiring board was proposed.

[0012]

However, a multilayer wiring board comprising a plurality of insulating layers formed by forming a coating layer made of a polyphenylene ether-based organic material on the upper and lower surfaces of a liquid crystal polymer layer has a thermal expansion coefficient of the coating layer. Since the thermal expansion coefficient of the liquid crystal polymer layer is different, cracks tend to occur in the coating layer in a temperature cycle test involving a rapid temperature change. There is also a method of preventing the cracks in the temperature cycle test by filling the coating layer with the inorganic insulating powder at a high density and making the thermal expansion coefficient of the coating layer substantially coincide with the thermal expansion coefficient of the liquid crystal polymer layer.
The adhesion between the coating layer and the wiring conductor is deteriorated, so that the wiring conductor cannot be adhered and formed. In addition, when the insulation layers are bonded to each other, the adhesion between the coating layers forming the insulation layer is deteriorated, and the insulation layer is formed. , And the insulating property is liable to be deteriorated.

The present invention has been devised in view of the above-mentioned problems of the prior art, and has as its object the purpose of having high-density wiring, and being excellent in solder heat resistance, insulation, high-frequency transmission characteristics, and temperature cycle characteristics. To provide a multi-layer wiring board.

[0014]

Means for Solving the Problems A multilayer wiring board according to the present invention has a structure in which a plurality of insulating layers are laminated with a wiring conductor made of a metal foil interposed therebetween, and a wiring conductor positioned above and below the insulating layer is interposed between the insulating layers. A multilayer wiring board electrically connected via a through conductor formed on an insulating layer, wherein the insulating layer is formed on the upper and lower surfaces of a liquid crystal polymer layer by a polyphenylene ether-based organic material, each of which is 60 to 80% inorganic. A first layer formed by combining insulating powder, a second layer formed by combining 40 to 60% by volume of inorganic insulating powder, and a third layer formed by combining 20 to 40% by volume of inorganic insulating powder. It is characterized by forming a coating layer formed by sequentially laminating.

Further, the multilayer wiring board of the present invention is characterized in that the polyphenylene ether-based organic substance is a polyphenylene ether modified to be thermosetting.

According to the multilayer wiring board of the present invention, the insulating layer is formed on the upper and lower surfaces of the liquid crystal polymer layer by bonding a 60-80% by volume of inorganic insulating powder with a polyphenylene ether organic material. A coating layer is formed by sequentially laminating a second layer composed of 40 to 60% by volume of inorganic insulating powder and a third layer composed of 20 to 40% by volume of inorganic insulating powder. As a result, the thermal expansion coefficient of the first layer in contact with the liquid crystal polymer layer in the coating layer approximates the thermal expansion coefficient of the liquid crystal polymer layer. As a result, cracks occur in the coating layer even in a temperature cycle test involving a rapid temperature change. It does not occur and a highly reliable multilayer wiring board can be obtained. Further, the content of the inorganic insulating powder in the third layer is set to 20.
4040% by volume, the adhesion between the coating layer and the wiring conductor deteriorates, making it impossible to form the wiring conductor on the coating layer. It does not occur that the adhesion between the coating layers forming the layer is deteriorated and the insulating properties are reduced due to separation between the insulating layers.

Further, according to the multilayer wiring board of the present invention,
Since the polyphenylene ether-based organic material is a thermosetting polyphenylene ether, the coating layer made of the cured polyphenylene ether-based organic material has a small melting deformation, and is heated when the insulating layers are sequentially laminated to form a multilayer wiring board. -It is possible to provide a multilayer wiring board with excellent conduction reliability in which displacement between the through conductor and the wiring conductor due to pressure is less likely to occur.

[0018]

Next, a multilayer wiring board of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on a multilayer wiring board according to the present invention. FIG. 2 is a sectional view showing the multilayer wiring board shown in FIG. 3 is an enlarged sectional view of a main part of FIG. In these figures, reference numeral 1 denotes an insulating layer, 2 denotes a wiring conductor, and 3 denotes a through conductor, and these mainly constitute a multilayer wiring board 4 of the present invention. In this example, a multi-layer wiring board 4 formed by laminating four insulating layers 1 is shown.

The insulating layer 1 is composed of a liquid crystal polymer layer 5 and a coating layer 6 formed by bonding an inorganic insulating powder with a polyphenylene ether-based organic substance adhered to the surface of the liquid crystal polymer layer 5. It has a function as a support for the mounted electronic component 7 and the wiring conductor 2.

Here, the liquid crystal polymer refers to a polymer having a liquid crystal state or an optically birefringent property when melted, and generally a lyotropic liquid crystal polymer which exhibits liquid crystallinity in a solution state or a thermotropic liquid crystal polymer which exhibits liquid crystallinity when melted. It includes a liquid crystal polymer or a liquid crystal polymer of all types 1, 2, and 3 classified by heat distortion temperature. The polyphenylene ether-based organic material is a polyphenylene ether resin or a resin in which various functional groups are bonded to polyphenylene ether, or a derivative or a derivative thereof.
It means a polymer.

Further, the liquid crystal polymer preferably has a melting point at a temperature of 200 to 400 ° C., particularly 250 to 350 ° C., from the viewpoint of temperature cycle reliability, solder heat resistance and workability. Light stabilizers such as an antioxidant for improving thermal stability and an ultraviolet absorber for improving light resistance, and a halogen or phosphoric acid for improving flame retardancy, as long as the physical properties of the compound are not impaired. -Based flame retardants, antimony-based compounds, flame-retardant aids such as zinc borate, barium metaborate, and zirconium oxide; higher fatty acids and higher fatty acid esters to improve lubricity; higher fatty acid metal salts; and fluorocarbon-based interfaces Lubricants such as activators, aluminum oxide / silicon oxide / titanium oxide /
Barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate, aluminum borate, barium stannate, barium zirconate -It may contain a filler such as strontium zirconate.

The particle shape of the above-mentioned filler and the like includes a substantially spherical shape, a needle shape, a flake shape and the like, and a substantially spherical shape is preferred from the viewpoint of filling properties. The particle size is usually about 0.1 to 15 μm, which is smaller than the thickness of the liquid crystal polymer layer 5.

Further, the surface of the liquid crystal polymer layer 5 is buffed, blasted, brushed, and plasma-treated in order to improve the adhesion with the coating layer 6 formed by binding an inorganic insulating powder with a polyphenylene ether-based organic substance. -It is preferable that the surface is roughened using a method such as corona treatment, ultraviolet treatment, or chemical treatment so that the center line surface roughness Ra has a value of 0.05 to 5 µm. The center line surface roughness Ra is preferably 0.05 μm or more from the viewpoint of preventing separation of the liquid crystal polymer layer 5 and the coating layer 6 during solder reflow. When the coating layer 6 is formed on the surface, From the viewpoint of preventing air entrapment, the thickness is preferably 5 μm or less.

The coating layer 6 formed by binding the inorganic insulating powder with a polyphenylene ether-based organic material forms the insulating layer 1
Has a function of an adhesive when the wiring conductor 2 is adhered and formed, and also functions as an adhesive when the insulating layers 1 are laminated.

The coating layer 6 contains 20 to 80% by volume of a polyphenylene ether-based organic material such as a polyphenylene ether resin or a derivative thereof, or a polymer alloy thereof. From the viewpoint, it is preferable to contain a thermosetting polyphenylene ether such as an allyl-modified polyphenylene ether.

If the content of the polyphenylene ether-based organic substance is less than 20% by volume, the kneadability tends to decrease, and if it exceeds 80% by volume, the liquid crystal polymer layer 5
When the coating layer 6 is formed on the surface, the thickness variation of the coating layer 6 tends to increase. Therefore, the content of the polyphenylene ether-based organic substance is preferably in the range of 20 to 80% by volume.

The coating layer 6 has two or more functional groups capable of performing a polymerization reaction from the viewpoint of improving the adhesiveness to the liquid crystal polymer layer 5 and the adhesiveness to the wiring conductor 2 and the through conductor 3. It is preferable to contain an additive such as a polyfunctional monomer or a polyfunctional polymer. For example, it is preferable to contain triallyl cyanurate, triallyl isocyanurate, and a polymer thereof.

Further, the coating layer 6 comprises a first layer 6 formed by bonding 60 to 80% by volume of an inorganic insulating powder to the upper and lower surfaces of a liquid crystal polymer layer with a polyphenylene ether organic material.
a and 40 to 60% by volume of an inorganic insulating powder.
It is formed by sequentially laminating a layer 6b and a third layer 6c formed by bonding 20 to 40% by volume of inorganic insulating powder. This is important in the present invention.

In the multilayer wiring board 4 of the present invention, since the covering layer 6 is configured as described above, the thermal expansion coefficient of the first layer 6a approximates the thermal expansion coefficient of the liquid crystal polymer layer 5,
As a result, cracks can be prevented from occurring in the coating layer 6 even in a temperature cycle test involving a rapid temperature change. Further, since the content of the inorganic insulating powder in the third layer 6c is as small as 20 to 40% by volume,
The adhesion between the coating layer 6 and the wiring conductor 2 becomes poor, and the coating layer 6
The wiring conductor 2 cannot be formed on the
When the insulating layers 1 are bonded to each other, there is no possibility that the adhesion between the coating layers 6 forming the insulating layer 1 is deteriorated and the insulating layers 1 are separated and the insulating property is not deteriorated.

The thickness of the first layer 6a is 0.2 from the viewpoint that the thermal expansion coefficient of the coating layer 6 is approximated to that of the liquid crystal polymer layer 5 when the thickness of the coating layer 6 is T.
T or more is preferable, and from the viewpoint of satisfactorily embedding the wiring conductor 2 in the coating layer 6, it is preferably less than 0.3T. In addition, the thickness of the second layer 6b is determined from the viewpoint of reducing the stress caused by the difference in the coefficient of thermal expansion between the first layer 6a and the third layer 6c.
0.4T or more is preferable, the effect of approximating the thermal expansion coefficient of the first layer 6a to the liquid crystal polymer layer 5 and the effect of the third layer 6c
0.6T or less is preferable from the viewpoint of sufficiently exhibiting the adhesiveness of the above. The thickness of the third layer 6c is preferably 0.2T or more from the viewpoint of improving the adhesion to the disposed wiring conductor 2, and is preferably less than 0.3T from the viewpoint of preventing disconnection due to thermal expansion in the thickness direction. preferable.

Further, the content of the inorganic insulating powder in the first layer 6a is preferably not less than 60% by volume from the viewpoint of approximating the coefficient of thermal expansion of the liquid crystal polymer layer 5; From the viewpoint of improving the adhesion to the layer 6b, the content is preferably 80% by volume or less.
The content of the inorganic insulating powder in the second layer 6 b is
It is preferably 40% by volume or more from the viewpoint of relaxing the stress caused by the difference in thermal expansion coefficient from the third layer 6c, and from the viewpoint of relaxing the stress caused by the difference in the thermal expansion coefficient from the third layer 6c. It is preferable that the content is not more than% by volume. The content of the inorganic insulating powder in the third layer 6c is preferably 20% by volume or more from the viewpoint of preventing resin flow during the pressurization process when the insulating layer 1 is laminated. The content is preferably 40% by volume or less from the viewpoint of improving the properties and the adhesion between the third layers 6c.

When the thickness T of the coating layer 6 is less than 10 μm, the thickness of the third layer 6 c becomes too thin as less than 2 μm, and the adhesiveness to the wiring conductor 2 tends to be reduced. If the thickness exceeds 3, the thickness of the third layer 6c exceeds 20 μm, and when the insulating layer 1 is laminated, resin flow is likely to occur in the third layer 6c, which tends to cause misalignment. Therefore, the thickness T of the coating layer 6 is preferably in the range of 10 to 100 μm.

The inorganic insulating powder of the coating layer 6 is, for example, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate. Barium titanate, strontium titanate, calcium titanate, aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. are used.

The shape of the above-mentioned inorganic insulating powder has a substantially spherical shape, a needle shape, a flake shape, and the like.
A substantially spherical shape is preferred. The particle diameter is about 0.1 to 15 μm, which is smaller than the thickness of the coating layer 6.

The coating layer 6 is made of a light stabilizer such as a rubber component for adjusting the elastic modulus, an antioxidant for improving thermal stability, and an ultraviolet absorber for improving light resistance. Halogen or phosphoric acid-based flame retardants to improve flammability, antimony compounds and flame-retardant aids such as zinc borate, barium metaborate, zirconium oxide, higher fatty acids to improve lubricity, Lubricants such as higher fatty acid esters, higher fatty acid metal salts and fluorocarbon surfactants, silane-based coupling agents and titanate-based coupling agents to improve affinity with fillers and improve their bonding properties and mechanical strength And the like.

The insulating layer 1 has a particle size of, for example, 0.1
A thermosetting polyphenylene ether resin and a solvent, a plasticizer, etc., so that the content of the inorganic insulating powder after drying is 60 to 80% by volume in an inorganic insulating powder such as silicon oxide of about 15 μm or so.
A paste obtained by adding a dispersant or the like is formed on the upper and lower surfaces of the liquid crystal polymer layer 5 by using a sheet forming method such as a conventionally known doctor blade method to form a first layer 6a to be a part of the coating layer 6, Alternatively, the first layer 6a is formed on the surface of the liquid crystal polymer layer 5 by immersing the liquid crystal polymer layer 5 in the above paste and vertically pulling it up, and heating and drying at a temperature of 40 to 100 ° C. for 5 minutes to 3 hours. Then, the first layer 6a is deposited on the surface of the insulating layer 1, and subsequently, the second layer 6b having an inorganic insulating powder content of 40 to 60% by volume and the third layer 6 having a content of 20 to 40% by volume. 6c is sequentially formed by the same method as the first layer 6a. Alternatively, the particle size is 0.1
A thermosetting polyphenylene ether resin and a solvent, a plasticizer, etc., so that the content of the inorganic insulating powder after drying is about 40 to 60% by volume in an inorganic insulating powder such as silicon oxide of about 15 μm or so.
Add a dispersant, etc. to increase the viscosity at a shear rate of 1000 s ^-1
The paste having a thickness of 000 to 3000 Pa · s is coated on the upper and lower surfaces of the liquid crystal polymer layer 5 by using a sheet forming method such as a doctor blade method which is well known in the art.
After the secondary drying, the secondary drying is performed at 60 to 100 ° C. for 15 to 60 minutes, and the liquid crystal polymer layer 5
On the side, a first layer 6a having a content of inorganic insulating powder of 60 to 80% by volume, a second layer 6b having a content of inorganic insulating powder of 40 to 60% by volume, and an inorganic insulating powder thereon It is also possible to form the third layer 6c having a content of 20 to 40% by volume at a time. In this case, the first layer 6a, the second layer 6b, and the third layer 6c have the desired thickness and content by adjusting the thickness and the content of the inorganic insulating powder by adjusting the viscosity of the paste and the drying temperature and the drying time. can do.

The thickness of the liquid crystal polymer layer 5 should be 1 to 20 times the thickness T of the coating layer 6 from the viewpoint of ensuring high heat resistance, low moisture absorption, and high dimensional stability. Is preferred.

The wiring conductor 2 is formed on at least one of the upper and lower surfaces of the insulating layer 1. The wiring conductor 2 has a thickness of about 2 to 30 μm and is made of a highly conductive metal foil such as copper or gold, and electrically connects the electronic components 7 mounted on the multilayer wiring board 4 to an external electric circuit (not shown). It has the function of connecting to

In order to prevent the occurrence of voids around the wiring conductor 2 when a plurality of insulating layers 1 are laminated, such a wiring conductor 2 has at least the surface of the wiring conductor 2 on the covering layer 6. It is preferable that the surface of the coating layer 6 is buried so as to be flat. When the porosity of the coating layer 6 in the dry state is set to 3 to 40% by volume when the wiring conductor 2 is embedded in the coating layer 6, the resin swelling of the coating layer 6 around the wiring conductor 2 does not occur. The flattening can be performed, and the air trapped between the wiring conductor 2 and the coating layer 6 can be easily discharged to prevent air bubbles from being trapped. When the porosity in the dry state exceeds 40% by volume,
After pressurizing and heating and curing the laminated insulating layer 1, pores remain in the coating layer 6, and the pores adsorb moisture in the air and reduce the insulating property of the coating layer 6. Since there is a possibility that the porosity of the coating layer 6 in a dry state is 3 to
It is preferable to set the range to 40% by volume.

The porosity of the coating layer 6 in the dry state can be adjusted by appropriately controlling the drying conditions such as the drying temperature and the heating rate when the coating layer 6 is applied on the surface of the liquid crystal polymer layer 5 and dried. By doing so, the porosity can be set to a desired value.

The lower surface of the wiring conductor 2 is formed on the second layer 6 b of the coating layer 6 from the viewpoint of the adhesion to the coating layer 6.
Alternatively, it is preferable to be buried so as to be located in the third layer 6c. When the lower surface of the wiring conductor 2 is located on the first layer 6 a of the coating layer 6, the first layer 6 a has a high content of the inorganic insulating powder of 60 to 80% by volume, so that the adhesion to the wiring conductor 2 is large. At the interface between the coating layer 6 and the wiring conductor 2. Therefore, the lower surface of the wiring conductor 2 has the coating layer 6.
It is important to be located on the second layer 6b or the third layer 6c, and particularly preferably located on the third layer 6c.

Further, the wiring conductor 2 provided on the insulating layer 1
Has a trapezoidal shape in which the length of the base on the insulating layer 1 side is shorter than the length of the opposing base, and the angle between the base and the side on the insulating layer 1 side is 95 to 150 °. It is preferable that The cross-sectional shape in the width direction of the wiring conductor 2 disposed on the insulating layer 1 is trapezoidal in which the length of the base on the side of the insulating layer 1 is shorter than the length of the opposite base, and the width of the base on the side of the insulating layer 1 By setting the angle between the side and the side at 95 to 150 °, when the wiring conductor 2 is embedded in the coating layer 6, the wiring conductor 2
Can be easily embedded in the coating layer 6. In addition, from the viewpoint of burying without entrapping air bubbles, it is preferable that the angle between the bottom side and the side of the insulating layer 1 is 95 ° or more, and from the viewpoint of miniaturizing the wiring conductor 2, it is 15 °.
Preferably, it is 0 ° or less.

Such a wiring conductor 2 is formed by depositing a metal foil made of, for example, copper, which is patterned by a subtractive method using a known photoresist, on a precursor sheet to be the insulating layer 1 by a transfer method or the like. It is formed by this. First, a metal foil transfer film is prepared by bonding a metal foil made of copper on a film serving as a support with an adhesive, and then the metal foil on the film is subjected to a subtractive method using a known photoresist. Is used to etch in a pattern. At this time, the side surface on the front side of the pattern
Since the contact time with the etching solution is longer than that of the side surface on the film side, etching is easy, and the cross-sectional shape in the width direction of the pattern can be trapezoidal. The trapezoidal shape can be formed into a trapezoidal shape in which the angle between the short base and the side is 95 to 150 ° by adjusting the concentration of the etching solution and the etching time. Then, this metal foil transfer film is laminated on a precursor sheet to be the insulating layer 1, and the temperature is 100 to 200 ° C. and the pressure is 0.5 to 10 MPa for 10 minutes to 1 hour.
After hot pressing for a period of time, the film serving as the support is peeled off and the metal foil is transferred to the surface of the precursor sheet serving as the insulating layer 1, so that the trapezoidal upper and lower sides become the coating layer 6 made of a polyphenylene ether-based organic material. The buried wiring conductor 2 can be formed.

The position of the lower surface of the wiring conductor 2 can be arranged in a desired area of the coating layer 6 by adjusting the pressure of the hot press during the transfer of the metal foil. The surface of the wiring conductor 2 is preferably roughened by a process such as buffing, blasting, brushing, or chemical treatment in order to enhance the adhesion to the coating layer 6.

The insulating layer 1 has a diameter of 20 to 150 μm.
The through conductor 3 is formed to a degree. The through conductor 3 has a function of electrically connecting the wiring conductors 2 positioned above and below the insulating layer 1, and after forming a through hole by drilling the insulating layer 1 with a laser, Copper /
It is formed by embedding a conductive paste made of silver, gold, solder or the like by a conventionally known screen printing method.

According to the multilayer wiring board 4 of the present invention, the insulating layer 1 is formed on the upper and lower surfaces of the liquid crystal polymer layer 5 by coating the inorganic insulating powder with a polyphenylene ether organic material.
Formed from the liquid crystal polymer layer 5
And the coating layer 6 made of a polyphenylene ether-based organic material has a low dielectric constant and is almost equal to each other, so that it has excellent transmission characteristics in a high-frequency region of 100 MHz or more, and even if a slight thickness variation occurs during lamination, the transmission characteristics in a high-frequency region The liquid crystal polymer layer 5 has high heat resistance, high elastic modulus, high dimensional stability, low moisture absorption, and glass cloth. It is possible to form the insulating layer 1 without using a reinforcing material as described above, and as a result, drilling with a laser is facilitated and fine and uniform through holes can be formed.

In such a multilayer wiring board 4, after forming the through conductor 3 at a desired position on the precursor sheet to be the insulating layer 1 manufactured by the method described above, a patterned metal foil of, for example, copper is formed. , Temperature is 100 ~ 200 ℃ and pressure is 0.5 ~ 10
Transfer by hot pressing under the condition of MPa for 10 minutes to 1 hour,
These are laminated and finally the temperature is 150-300 ° C and the pressure is 0.
It is manufactured by hot-pressing under conditions of 5 to 10 MPa for 30 minutes to 24 hours to completely cure.

Thus, according to the multilayer wiring board 4 of the present invention, the insulating layer 1 is formed on the upper and lower surfaces of the liquid crystal polymer layer 5 by 60-80% by volume of a polyphenylene ether organic material.
A first layer 6a formed by combining inorganic insulating powders of the following, a second layer 6b formed by combining 40 to 60% by volume of inorganic insulating powder,
Since the coating layer 6 is formed by sequentially laminating a third layer 6c formed by bonding 40% by volume of inorganic insulating powder, the first layer in contact with the liquid crystal polymer layer 5 in the coating layer 6 is formed. 6a is close to the thermal expansion coefficient of the liquid crystal polymer layer 5. As a result, no cracks occur in the coating layer 6 even in a temperature cycle test involving a rapid temperature change, and the highly reliable multilayer wiring board 4 It can be. Further, the content of the inorganic insulating powder in the third layer 6c is set to 20 to 40.
Since the volume% is small, the adhesion between the coating layer 6 and the wiring conductor 2 is deteriorated, so that the wiring conductor 2 cannot be formed on the coating layer 6 or the insulating layers 1 are bonded to each other. In this case, the adhesion between the coating layers 6 forming the insulating layer 1 is not deteriorated, and the insulating properties are not degraded due to the separation between the insulating layers 1.

The multilayer wiring board 4 of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Manufactured the multilayer wiring board 4 by laminating the four insulating layers 1;
The multilayer wiring board 4 may be manufactured by laminating more than one insulating layer 1. Further, on the upper and lower surfaces of the multilayer wiring board 4 of the present invention,
One, two, or three or more build-up layers or solder resist layers composed of an insulating layer mainly containing an organic resin may be formed.

[0051]

EXAMPLES Next, the following samples were manufactured and evaluated for the multilayer wiring board of the present invention. (Example) First, a thermosetting polyphenylene ether resin has an average particle size of 0.6 μm.
Is added so that the content becomes 70% by volume in a dry state, and toluene is added as a solvent, and a catalyst for accelerating the curing of the organic resin is added thereto, and mixed for 1 hour to prepare a paste. did. Next, the surface of the liquid crystal polymer layer having a melting point of 320 ° C. is subjected to plasma treatment to prepare a liquid crystal polymer layer having a thickness of 35 μm and a center line surface roughness Ra of 0.10 μm, and the above paste is applied to the upper surface of the liquid crystal polymer layer. It was applied by a doctor blade method to form a first layer of thermosetting polyphenylene ether in a dry state having a thickness of about 10 μm. Then, a paste adjusted so that the spherical fused silica content was 50% by volume in a dry state was applied thereon in the same manner to form a second layer having a thickness of about 20 μm. further,
A paste adjusted to have a spherical fused silica content of 30% by volume in a dry state was applied thereon by the same method to form a third layer having a thickness of about 10 μm. Similarly, a first layer, a second layer, and a third layer are manufactured on the lower surface of the liquid crystal polymer layer.
A precursor sheet to be an insulating layer was obtained.

Next, a through hole having a diameter of 65 μm was formed in the precursor sheet by a CO ₂ laser, and a conductive paste containing copper powder and an organic binder was embedded in the through hole by screen printing to form a through conductor. did.

Further, a transfer supporting film having a 12 μm-thick copper foil formed in a circuit shape and a precursor sheet to be an insulating layer having a through conductor formed thereon are aligned with each other, and are subjected to 3 MPa by a vacuum laminator. After applying pressure for 30 seconds, the transfer support film was peeled off, and the wiring conductor was embedded on the precursor sheet. Finally, four precursor sheets on which the wiring conductors are formed are superimposed, and a pressure of 3 MPa and a temperature of 200 ° C.
A heating treatment was performed for a period of time to complete the curing, thereby obtaining a multilayer wiring board.

In a test board for evaluating insulation, a wiring conductor having a comb-tooth pattern with a wiring width of 50 μm and a wiring interval of 50 μm is formed in a multilayer wiring board, and the temperature cycle resistance is evaluated. The test board used for this test had a via chain formed of two upper and lower wiring conductors located inside the insulating layer of the multilayer wiring board and through conductors electrically connecting the two.

(Comparative Example 1) The multilayer wiring board used for Comparative Example 1 was prepared by applying a paste adjusted so that the spherical fused silica content was 50% by volume in a dry state to a liquid crystal polymer layer by a doctor blade method. The procedure was performed in the same manner as in Example 1 except that a coating layer having a thickness of 40 μm was formed.

The thickness of the coating layer of the multilayer wiring board used for Comparative Example 1 was 40 μm, and the silica content was 51% by volume within a range of 10 μm from the interface between the liquid crystal polymer layer and the coating layer. , Within the range of 10-30 μm
% By volume, and 49% in the range of 30 to 40 μm.
% By volume, and the silica content of the coating layer was almost uniform.

Comparative Example 2 The multilayer wiring board used for Comparative Example 2 was prepared by applying a paste adjusted so that the content of spherical fused silica was 70% by volume in a dry state to a liquid crystal polymer layer by a doctor blade method. The procedure was performed in the same manner as in Example 1 except that a coating layer having a thickness of 40 μm was formed.

The thickness of the coating layer of the multilayer wiring board used for Comparative Example 2 was 40 μm, and the silica content was 72% by volume within a range of 10 μm from the interface between the liquid crystal polymer layer and the coating layer. , 70 in the range of 10-30 μm
% By volume, and 68% within the range of 30 to 40 μm.
% By volume, and the silica content of the coating layer was almost uniform.

The insulation was evaluated by subjecting the sample to a high-temperature bias test with an applied voltage of 5.5 V at a temperature of 130 ° C. and a relative humidity of 85%, and measuring the insulation resistance between the wiring conductors after 300 hours. Evaluation was made by comparing the amount of change before and after the test.
In addition, the evaluation of temperature cycle resistance was performed by setting the sample to -55 ° C.
A temperature cycle test was performed with one cycle of 30 minutes at 125 ° C. and 30 minutes at 125 ° C., the conduction resistance of the via chain after 2,000 cycles was measured, and the amount of change before and after the test was evaluated.

Table 1 shows the evaluation results of the insulation properties, and Table 2 shows the evaluation results of the temperature cycle resistance.

[0061]

[Table 1]

[0062]

[Table 2]

From Table 1, it was found that the multilayer wiring board of Comparative Example 2 had an extremely low insulation resistance of 2.9 × 10 ⁵ Ω after 300 hours of the high-temperature bias test, and was inferior in heat resistance. Table 2 shows that the multilayer wiring board of Comparative Example 1 was subjected to the temperature cycle test.
The rate of change of the conduction resistance after 2000 cycles was 21%, indicating that the temperature cycle resistance was poor.

On the other hand, the multilayer wiring board of the present invention
2.3 × 10 ¹⁰ Ω insulation resistance even after 300 hours of high temperature bias test
And the rate of change was as small as 3% even after 2000 cycles of the temperature cycle test.

[0065]

According to the multilayer wiring board of the present invention, the insulating layer is formed on the upper and lower surfaces of the liquid crystal polymer layer by bonding a 60-80% by volume of inorganic insulating powder with a polyphenylene ether organic material. And a second layer formed by combining 40 to 60% by volume of inorganic insulating powder, and a third layer formed by combining 20 to 40% by volume of inorganic insulating powder to form a coating layer. Therefore, the thermal expansion coefficient of the first layer in contact with the liquid crystal polymer layer in the coating layer approximates the thermal expansion coefficient of the liquid crystal polymer layer. As a result, even in a temperature cycle test involving a sudden temperature change, Cracks do not occur and a highly reliable multilayer wiring board can be obtained. Further, the content of the inorganic insulating powder in the third layer is set to 20.
4040% by volume, the adhesion between the coating layer and the wiring conductor deteriorates, making it impossible to form the wiring conductor on the coating layer. It does not occur that the adhesion between the coating layers forming the layer is deteriorated and the insulating properties are reduced due to separation between the insulating layers.

Further, according to the multilayer wiring board of the present invention,
Since the polyphenylene ether-based organic material is a thermosetting polyphenylene ether, the coating layer made of the cured polyphenylene ether-based organic material has a small melting deformation, and is heated when the insulating layers are sequentially laminated to form a multilayer wiring board. -It is possible to provide a multilayer wiring board with excellent conduction reliability in which displacement between the through conductor and the wiring conductor due to pressure is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on a multilayer wiring board of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the multilayer wiring board of the present invention.

[Explanation of symbols]

 1 ... insulating layer 2 ... wiring conductor 3 ... through conductor 4 ... multilayer wiring board 5 ... liquid crystal polymer layer 6 ... coating layer 6a: first layer 6b: second layer 6c: third layer T: thickness of coating layer

Continued on the front page F-term (reference) 4F100 AA20 AK01A AK54B AK54C AK54D AK54E AS00A BA05 BA06 BA07 BA10C BA27 CA30B CA30C CA30D CA30E EH46 GB43 JG04 JJ03 YY00B YY00C YY00D YY00E 5E346 AA02 CC

Claims (2)

[Claims] 1. A plurality of insulating layers are laminated with a wiring conductor made of a metal foil interposed therebetween, and a through conductor formed in the insulating layer is formed between the wiring conductors located above and below the insulating layer. A multi-layer wiring board electrically connected to each other via a liquid crystal polymer layer, wherein the insulating layer is formed on the upper and lower surfaces of the liquid crystal polymer layer by a polyphenylene ether-based organic material.
A first layer formed by bonding 0% by volume of an inorganic insulating powder;
A second layer formed by bonding 無機 60% by volume of an inorganic insulating powder;
A multilayer wiring board comprising a coating layer formed by sequentially laminating a third layer formed by bonding 20 to 40% by volume of an inorganic insulating powder. 2. The multilayer wiring board according to claim 1, wherein the polyphenylene ether-based organic substance is a thermosetting polyphenylene ether.