JP2007335835A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress remaining of heat from a heating component and to discourage cracking at the soldering part for connecting a mounting component, relating to a wiring board that has an electric wiring at least on one surface, with the heating component being mounted. <P>SOLUTION: The total thickness of a first metal layer 3 and a second metal layer 4 on both surfaces of a first resin insulating layer 5 is set to be larger than the first resin insulating layer 5, with the edge of the first metal layer 3 positioned inside the peripheral edge of the first resin insulating layer 5. The thermal expansion coefficient of the first metal layer 3 in planar direction is set smaller than that of the second metal layer 4 in planar direction. The thermal conductivity of the first metal layer 3 is set higher than that of the second metal layer 4. A reinforcing fiber packed second resin insulating layer 6 whose thickness is equal to or more than that of the first metal layer, contacting the entire periphery of the edge of the first metal layer 3, is added to the first resin insulating layer 5. The first resin insulating layer 5 is such highly thermally conductive insulating layer as formed of the insulating material having a higher thermal conductivity than the second resin insulating layer 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring board having high heat dissipation characteristics and high connection reliability even in a configuration in which a heat generating component is mounted.

  A wiring board mounted on an electronic device is required to have a technology for fine wiring and high-density mounting in accordance with a reduction in the thickness and size of the electronic device, and a technology for high heat dissipation corresponding to heat generation is also required. In particular, in electronic circuits such as automobiles that use a large current for various controls and operations, heat generation due to the resistance of the conductive circuit and heat generation from the power element are very large, and the heat dissipation characteristics of the wiring board may be high. It has become essential.

  As a countermeasure, prepare a laminated board in which a thick metal layer (copper plate or copper foil) is integrated with an insulating layer holding a thermosetting resin on a highly heat-dissipating ceramic substrate or sheet-like fiber base material. There is a circuit processed wiring board (for example, description in paragraph 0002 of Patent Document 1).

  In a wiring board in which a thick metal layer is integrated with an insulating layer holding a thermosetting resin on a sheet-like fiber base, mounting a heat-generating component such as a power element on the wiring board by soldering will cause thermal expansion / contraction of the metal layer. Stress is applied to the solder portion, and cracks are likely to occur in the solder portion.

JP 2003-198103 A

  The problem to be solved by the present invention is composed of a first resin insulation layer reinforced with a sheet-like fiber base material, a first metal layer and a second metal layer integrated on both sides thereof, and at least the first metal layer is In a wiring board having a function of electrical wiring and mounting a heat generating component on the electrical wiring of the first metal layer, it is possible to suppress heat retention due to the heat generating component, and to prevent a crack from occurring in a solder portion connected to the mounting component. It is.

  In order to achieve the above object, a wiring board according to the present invention (Claim 1) includes a first resin insulating layer reinforced with a sheet-like fiber base material, a first metal layer and a second metal integrated on both sides thereof. In the configuration in which the first metal layer has a function of electric wiring, at least the first metal layer has a function of electric wiring, and a heat generating component is mounted on the electric wiring of the first metal layer. The total thickness of the first metal layer and the second metal layer is set to be thicker than the thickness of the first resin insulation layer, and the edge of the first metal layer is located inside the periphery of the first resin insulation layer. The thermal expansion coefficient in the planar direction of the first metal layer is set smaller than the thermal expansion coefficient in the planar direction of the second metal layer, and the thermal conductivity of the first metal layer is set higher than the thermal conductivity of the second metal layer. Is done. The first resin insulating layer is further provided with a reinforcing fiber-filled second resin insulating layer that is in contact with the entire periphery of the edge of the first metal layer and has a thickness equal to or greater than the thickness of the first metal layer. The insulating layer is a highly thermally conductive insulating layer formed of an insulating material having a higher thermal conductivity than the second resin insulating layer.

  In the first aspect, preferably, the thermal conductivity of the first resin insulating layer is 4 W / m · K or more (claim 2). Furthermore, the thermal expansion coefficient in the planar direction of the second resin insulating layer is smaller than the thermal expansion coefficient of the first metal layer (Claim 3).

  When a heat-generating component such as a power element is mounted on a metal layer having a function of electrical wiring, the thermal expansion coefficient of the power element is about 5 ppm / ° C. On the other hand, the coefficient of thermal expansion (α) of the metal layer directly under the power element is about 9 to 30 ppm / ° C. If the heat cycle of the power element is repeated and the heat generation is stopped, stress is concentrated on the solder part that joins the two due to the difference in the coefficient of thermal expansion between the two, causing cracks in the solder part and connecting. Reliability decreases.

However, in the wiring board according to the present invention, the first resin insulating layer is made of an insulating material that is thinner than the total thickness of the first metal layer and the second metal layer and has a higher thermal conductivity than the second resin insulating layer. Since the formed highly heat-conductive insulating layer is formed, the first resin insulating layer is less likely to hinder heat conduction, and the heat conductivity of the first metal layer and the second metal layer through the first resin insulating layer is reduced. Is ensured, and the temperature rise of the first metal layer itself is suppressed. Furthermore, since the thermal conductivity of the first metal layer is made higher than the thermal conductivity of the second metal layer, the heat generated by the power element is quickly transmitted through the first metal layer, and the heat dissipation is improved. Further, the first metal layer is regulated so that the entire circumference of the edge is in contact with the second resin insulating layer equal to or more than the thickness of the first metal layer, and the coefficient of thermal expansion in the planar direction of the first metal layer is the second. Since the thermal expansion coefficient in the planar direction of the metal layer is smaller than that, the thermal expansion in the planar direction of the first metal layer is suppressed. In this way, the expansion due to the temperature rise of the first metal layer is suppressed, and the stress applied to the solder portion is reduced.
Furthermore, the heat dissipation effect is increased by setting the thermal conductivity of the first resin insulating layer to 4 W / m · K or more. Moreover, the effect of suppressing the thermal expansion in the planar direction of the first metal layer is increased by making the thermal expansion coefficient in the planar direction of the second resin insulating layer smaller than that of the first metal layer.

  As a specific form for carrying out the present invention, for example, a configuration as shown in FIG. The first metal layer 3 and the second metal layer 4 are integrated on both surfaces of the first resin insulating layer 5 reinforced with the sheet-like fiber base material, and at least the first metal layer 3 has a function of electric wiring. The heating element 1 is mounted with solder 2 on the first metal layer having the function of electrical wiring. The total thickness of the first metal layer 3 and the second metal layer 4 integrated on both surfaces of the first resin insulation layer 5 is set to be greater than the thickness of the first resin insulation layer 5. Further, the edge of the first metal layer 3 is located inside the periphery of the first resin insulating layer 5. Furthermore, the thermal expansion coefficient in the planar direction of the first metal layer 3 is smaller than the thermal expansion coefficient in the planar direction of the second metal layer 4, and the thermal conductivity of the first metal layer 3 is the thermal conductivity of the second metal layer 4. It is set higher than the rate. The first resin insulating layer 5 is provided with a reinforcing fiber-filled second resin insulating layer 6 that is in contact with the entire periphery of the first metal layer 3 and has a thickness equal to or greater than the thickness of the first metal layer 3. . Here, the first resin insulation layer 5 is a high thermal conductivity insulation layer formed of an insulation material having a higher thermal conductivity than the second resin insulation layer 6.

  In the above configuration, first, the first metal layer 3 and the second metal layer 4 are arranged on both surfaces of the prepreg layer in which the thermosetting resin is held on the sheet-like fiber base material, and integrated by heat and pressure molding. To do. The prepreg layer becomes the first resin insulating layer 5 by the molding. And the 1st metal layer 3 is processed so that the edge of the 1st metal layer 3 may be located inside the periphery of the 1st resin insulation layer 5, and it is set as a plate-like body with a double-sided metal layer. This processing includes processing so that the first metal layer has a function of electric wiring. In addition, the 1st metal layer and 2nd metal layer which were previously processed into the predetermined shape are arrange | positioned on both surfaces of the said prepreg layer, and it is good also as a plate-like body with a double-sided metal layer by integrating by heat-pressure molding.

Next, the second resin insulating layer 6 is formed by stacking a prepreg layer on the first metal layer 3 side of the plate with double-sided metal layers and integrating them by heat and pressure molding. The second resin insulating layer 6 on the first metal layer 3 is removed by polishing or counterboring to expose the first metal layer 3. In this way, the second resin insulation layer 6 is added to the first resin insulation layer 5.
Then, the predetermined heating element 1 is mounted on a mounting region on the first metal layer 3 from which the second resin insulating layer 6 has been removed by means such as solder reflow.
The addition of the second resin insulating layer 6 is performed by adding the prepreg layer from which the region facing the first metal layer 3 has been removed in advance to the plate-like body with double-sided metal layers and integrating them by heat and pressure molding. The counterbore process can be omitted or simplified.

  In the above, since the thickness of the first resin insulating layer 5 is thinner than the total thickness of the first metal layer 3 and the second metal layer 4, by pressing the first metal layer 3 into the first resin insulating layer 5, The resin insulating layer cannot be in contact with the periphery of the edge of the first metal layer 3 beyond its thickness. It is essential to add the second resin insulation layer 6 to the first resin insulation layer 5.

The sheet-like fiber base material constituting the prepreg is a woven fabric or a nonwoven fabric made of glass fiber or organic fiber. In order to reduce the thermal expansion coefficient of the resin insulating layer, a sheet-like fiber base material made of aramid fiber or alumina fiber is preferable. The first resin insulating layer preferably has a thermal conductivity of 4 W / m · K or more. The thermosetting resin for impregnating the sheet-like fiber base material to form the resin insulating layer is, for example, as follows when the thermal conductivity of the resin insulating layer is 4 W / m · K or more. Adopt resin composition.
That is, an epoxy resin composition containing an inorganic filler and containing an epoxy resin monomer having a molecular structure represented by (Formula 1) is employed. The inorganic filler has a thermal conductivity of 20 W / m · K or more, and is present in the insulating layer in an amount of 10 to 185 parts by volume with respect to 100 parts by volume of the resin solid content.

上記（式１）で示す分子構造のエポキシ樹脂モノマは、ビフェニル骨格あるいはビフェニル誘導体の骨格をもち、１分子中に２個以上のエポキシ基をもつエポキシ化合物全般である。エポキシ樹脂モノマの硬化反応を進めるために、硬化剤を配合する。硬化剤は、例えば、アミン化合物やその誘導体、酸無水物、イミダゾールやその誘導体、フェノール類又はその化合物や重合体などである。また、エポキシ樹脂モノマと硬化剤の反応を促進するために、硬化促進剤を使用することができる。硬化促進剤は、例えば、トリフェニルホスフィン、イミダゾールやその誘導体、三級アミン化合物やその誘導体などである。

The epoxy resin monomers having the molecular structure represented by the above (formula 1) are all epoxy compounds having a biphenyl skeleton or a biphenyl derivative skeleton and having two or more epoxy groups in one molecule. In order to advance the curing reaction of the epoxy resin monomer, a curing agent is blended. Examples of the curing agent include amine compounds and derivatives thereof, acid anhydrides, imidazoles and derivatives thereof, phenols or compounds and polymers thereof, and the like. Moreover, in order to accelerate | stimulate reaction of an epoxy resin monomer and a hardening | curing agent, a hardening accelerator can be used. Examples of the curing accelerator include triphenylphosphine, imidazole and derivatives thereof, tertiary amine compounds and derivatives thereof, and the like.

The inorganic filler having a thermal conductivity of 20 W / m · K or more blended in the epoxy resin composition blended with the curing agent or curing accelerator is a metal oxide, hydroxide, inorganic ceramic, or other filler. For example, inorganic powder fillers such as boron nitride, aluminum nitride, silicon nitride, silicon carbide, titanium nitride, zinc oxide, tungsten carbide, alumina, magnesium oxide, fibrous fillers such as synthetic fibers and ceramic fibers, colorants, etc. is there. Two or more of these inorganic fillers may be used in combination.
An inorganic filler is mix | blended so that it may become the quantity of 10-185 volume parts with respect to 100 volume parts of resin solid content. The lower limit values of the thermal conductivity and blending amount of the inorganic filler are necessary when the thermal conductivity of the resin insulating layer is 4 W / m · K or more. Moreover, when there are few inorganic fillers mix | blended with an epoxy resin composition, it will become difficult to disperse | distribute an inorganic filler uniformly in an epoxy resin composition. In this respect as well as ensuring thermal conductivity, it is important to define the lower limit value of the inorganic filler content. On the other hand, when the blending amount of the inorganic filler is increased, the viscosity of the epoxy resin composition is increased and the handling becomes difficult. Therefore, the upper limit value of the blending amount of the inorganic filler is defined from this viewpoint.

  In addition, it is preferable if the thermal conductivity of the inorganic filler is 30 W / m · K or more because the thermal conductivity of the resin insulating layer can be further increased. Further, the inorganic filler may have any shape such as powder (bulk shape, spherical shape), short fiber, long fiber and the like. In addition to the above epoxy resin composition, a flame retardant, a diluent, a plasticizer, a coupling agent, and the like can be blended as necessary.

  The resin insulation layer is formed by preparing a prepreg in which the epoxy resin composition is diluted with a solvent as necessary to prepare a varnish, impregnating the varnish into a sheet-like fiber base material, and drying by heating to a semi-cured state. And these are heat-press-molded and it is set as a resin insulating layer. In the heat and pressure molding, metal layers are arranged on both surfaces of the prepreg layer, and these are integrated by heat and pressure molding. The metal layer may be either electrolytic metal or rolled metal.

In addition, since the first metal layer has a function of electrical wiring, it is common to use copper having high electrical conductivity, but copper / molybdenum alloy, copper / tungsten alloy, copper / chromium having low thermal expansion coefficient. It is preferable to use a copper alloy such as an alloy or a copper / invar alloy because the connection reliability can be further improved. Among these, a copper / chromium alloy is more preferable because it is inexpensive and can maintain connection reliability equivalent to that of a copper / molybdenum alloy. Although the electrical conductivity of these copper alloys is inferior to copper, there is no practical problem.
When the varnish is prepared by diluting the epoxy resin composition in a solvent, the blending and use of the solvent does not affect the thermal conductivity of the cured epoxy resin.

  Examples of the present invention will be described below, and the present invention will be described in detail. In the following examples and comparative examples, “part” means “part by mass”. Moreover, this invention is not limited to a present Example, unless it deviates from the summary.

The material specifications used in this example are as follows.
(A) Epoxy resin varnish a; 100 parts of an epoxy resin monomer having a biphenyl skeleton as an epoxy resin monomer component (Japan Epoxy Resin “YL6121H”, epoxy equivalent 175) is prepared, and this is methyl isobutyl ketone (Wako Pure Chemical Industries, Ltd.) It melt | dissolved in 100 parts at 100 degreeC, and returned to room temperature. The "YL6121H" the molecular structure described above in (Equation _{1), R = -CH 3,} n = 0.1 in which the epoxy resin monomer and molecular structural formula (Formula 1), R = -H, n = 0.1 An epoxy resin monomer containing an equimolar amount of an epoxy resin monomer of 0.1.
As a curing agent, 22 parts of 1,5-diaminonaphthalene (“1,5-DAN” manufactured by Wako Pure Chemical Industries, Ltd., amine equivalent 40) is prepared and dissolved in 100 parts of dimethylformamide (manufactured by Wako Pure Chemical Industries) at 100 ° C. , Returned to room temperature.
The above epoxy resin monomer solution and the curing agent solution are mixed and stirred to form a uniform varnish, and boron nitride (“HGPE” manufactured by Denki Kagaku Kogyo, average particle size: 8 μm, thermal conductivity 60 W / m 116 parts (corresponding to 67 parts by volume with respect to 100 parts by volume of the resin solid content) were added and kneaded to prepare an epoxy resin varnish a.
(B) Epoxy resin varnish b; 43 parts of boron nitride (“HGPE” manufactured by Denki Kagaku Kogyo), which is an inorganic filler in the epoxy resin varnish a, is added (corresponding to 25 parts by volume with respect to 100 parts by volume of resin solids). Except for kneading, an epoxy resin varnish b was prepared in the same manner as the epoxy resin varnish a.
(C) Epoxy resin varnish c: 75 parts of boron nitride (“HGPE” manufactured by Denki Kagaku Kogyo), which is an inorganic filler in the epoxy resin varnish a, is added (corresponding to 40 parts by volume with respect to 100 parts by volume of the resin solid content). Except for kneading, an epoxy resin varnish c was prepared in the same manner as the epoxy resin varnish a.
(D) Prepreg d: Epoxy resin varnish a was impregnated into a glass woven fabric having a thickness of 60 μm and dried by heating to obtain a prepreg having a thickness of 100 μm.
(E) Prepreg e; Epoxy resin varnish b was impregnated into a glass woven fabric having a thickness of 30 μm and dried by heating to obtain a prepreg having a thickness of 100 μm.
(F) Prepreg f: Epoxy resin varnish c was impregnated into a glass nonwoven fabric having a thickness of 80 μm and dried by heating to obtain a prepreg having a thickness of 100 μm.
(G) Prepreg g: Epoxy resin varnish a was impregnated into a glass nonwoven fabric having a thickness of 80 μm and dried by heating to obtain a prepreg having a thickness of 100 μm.

Example 1
Using one prepreg d, a 1.4 mm thick copper layer (thermal expansion coefficient: 17 ppm / ° C., thermal conductivity: 395 W / m · K) as the first metal layer on both sides, and 1 as the second metal layer A 4 mm thick aluminum plate (thermal expansion coefficient: 24 ppm / ° C., thermal conductivity: 200 W / m · K) is stacked, heated and pressed for 90 minutes under the conditions of a temperature of 175 ° C. and a pressure of 6 MPa, and integrated. A laminated plate having a thickness of 2.9 mm in which metal layers were integrated on both surfaces of the resin insulating layer was obtained. And the 1st metal layer (copper layer) was processed into the predetermined shape, and it was set as the plate-like body with a double-sided metal layer. The first resin insulating layer has a thermal expansion coefficient of 12 ppm / ° C. and a thermal conductivity of 3 W / m · K.

Next, the prepreg e is matched with the predetermined shape of the plate with the double-sided metal layer and the portion corresponding to the first metal layer is removed by punching, and then the plate-like body with the double-sided metal layer is moved to the first metal layer side. One sheet was placed, sandwiched between release films, and heated and pressed for 90 minutes under the conditions of a temperature of 175 ° C. and a pressure of 6 MPa, and the second resin insulation layer was integrated.
The release film is peeled off to obtain a wiring board having a configuration in which the second resin insulating layer added to the first resin insulating layer contacts the periphery of the first metal layer edge at the same height as the first metal layer (copper layer). It was. This corresponds to the configuration shown in FIG. The thermal expansion coefficient of the second resin insulation layer is 17 ppm / ° C., and the thermal conductivity is 2 W / m · K.

The results of measuring the thermal expansion coefficient, thermal conductivity, element heat generation temperature, and solder connection reliability of the wiring board obtained in Example 1 are shown together in Table 1 together with the configuration of the metal layer. The measurement is based on the method shown below.
Thermal expansion coefficient: A plate sample of 5 × 10 mm was cut out from the wiring board, and the thermal expansion coefficient in the plane direction in the range of 30 ° C. to 80 ° C. was measured by TMA measurement.
Thermal conductivity: A plate-like sample having a diameter of 50 mm was cut out from the wiring board, and the thermal conductivity in the thickness direction not including the metal layers on both sides was measured by a heat flow meter method (based on JIS-A1412).
Element heating temperature: A heating element (ceramic heater chip) is soldered to the first metal layer processed into a predetermined shape, and the second metal layer is cooled by cooling fins and kept at a constant temperature. A power of 80 W was input to the heating element, and the element temperature after 2 minutes of input was measured.
Solder connection reliability: A heating element (ceramic heater chip) is soldered to the first metal layer processed into a predetermined shape, a thermal cycle test is conducted in the range of 105 ° C to -40 ° C, and cracks in the solder part occur after 1000 cycles The presence or absence of was investigated.

Example 2
In Example 1, a wiring board was obtained in the same manner as in Example 1 except that the prepreg f was used as the first resin insulating layer. The first resin insulating layer has a thermal expansion coefficient of 18 ppm / ° C. and a thermal conductivity of 4 W / m · K.

Example 3
In Example 1, a wiring board was obtained in the same manner as in Example 1 except that prepreg g was used as the first resin insulating layer. The first resin insulating layer has a thermal expansion coefficient of 18 ppm / ° C. and a thermal conductivity of 5 W / m · K.

Example 4
In Example 3, a copper / molybdenum alloy (thermal expansion coefficient: 9 ppm / ° C., thermal conductivity: 220 W / m · K) having a thickness of 1.4 mm was used as the first metal layer. A wiring board was obtained.

Example 5
In Example 4, a wiring board was obtained in the same manner as in Example 4 except that prepreg d was used as the second resin insulating layer. The thermal expansion coefficient of the second resin insulation layer is 12 ppm / ° C., and the thermal conductivity is 3 W / m · K.

Example 6
In Example 5, the same procedure as in Example 5 was used except that a 1.5 mm thick copper / chromium alloy (thermal expansion coefficient: 10 ppm / ° C., thermal conductivity: 200 W / m · K) was used as the first metal layer. A wiring board was obtained.

Comparative Example 1
Using one prepreg g, a copper layer with a thickness of 1.4 mm as the first metal layer on both sides (thermal expansion coefficient: 17 ppm / ° C., thermal conductivity: 395 W / m · K), 1 as the second metal layer A 4 mm thick aluminum plate (thermal expansion coefficient: 24 ppm / ° C., thermal conductivity: 200 W / m · K) is stacked, heated and pressed for 90 minutes under the conditions of a temperature of 175 ° C. and a pressure of 6 MPa, and integrated. A laminated plate having a thickness of 2.9 mm in which metal layers were integrated on both surfaces of the resin insulating layer was obtained. The first metal layer (copper layer) is processed into a predetermined shape, and the second resin insulating layer is not added. This corresponds to the configuration shown in FIG. The first resin insulating layer has a thermal expansion coefficient of 18 ppm / ° C. and a thermal conductivity of 5 W / m · K.

Comparative Example 2
A wiring board was obtained in the same manner as in Example 1 except that prepreg e was used as the first resin insulating layer and prepreg d was used as the second resin insulating layer. The first resin insulating layer has a thermal expansion coefficient of 17 ppm / ° C. and a thermal conductivity of 2 W / m · K. The second resin insulating layer has a thermal expansion coefficient of 12 ppm / ° C. and a thermal conductivity of 3 W / m · K.

Comparative Example 3
In Example 3, a 1.4 mm thick aluminum plate (thermal expansion coefficient: 24 ppm / ° C., thermal conductivity: 200 W / m · K) as the first metal layer, and a 1.4 mm thick copper layer (second metal layer) A wiring board was obtained in the same manner as in Example 3 except that the coefficient of thermal expansion was 17 ppm / ° C. and the thermal conductivity was 395 W / m · K.

  For the wiring boards of Examples 2 to 5 and Comparative Examples 1 to 3, the characteristics were measured in the same manner as in Example 1, and the results are shown in Table 1.

As shown in the above table, in Comparative Example 1, there is nothing that regulates the periphery of the edge of the first metal layer, so the thermal expansion of the first metal layer cannot be suppressed, and the difference from the linear expansion of the heating element. Stress is generated from the solder and cracks in the solder part are likely to occur. In Comparative Example 3, since the thermal expansion of the first metal layer that solder-connects the heating elements is larger than the thermal expansion of the second metal layer, the number of cracks in the solder portion is increased.

  In the embodiment according to the present invention, the first resin insulation layer is a high thermal conductivity insulation layer made of an insulation material having a higher thermal conductivity than the second resin insulation layer. It can be understood that conduction is hardly hindered, thermal conductivity from the first metal layer to the second metal layer is ensured, and the element heat generation temperature and the number of cracks in the solder portion are suppressed (Example 1). To 5 and Comparative Example 2). In addition, it can be understood that when the thermal conductivity of the first resin insulating layer is 4 W / m · K or more, the heat generation of the element is suppressed and the heat dissipation effect is increased (Examples 2 to 6 and Example 1). Contrast). The first metal layer is copper or a copper alloy, and has a sufficiently high thermal conductivity to transfer heat from the heating element. On the other hand, the first resin insulating layer has a significantly lower thermal conductivity than the metal, and heat from the heating element tends to be trapped. In such a situation, the difference in thermal conductivity of 1 W / m · K and 2 W / m · K of the first resin insulating layer affects the suppression of the temperature rise of the heating element and the improvement of the solder connection reliability. It will be.

(A) is sectional drawing of the wiring board of embodiment which concerns on this invention, (b) is sectional drawing of the conventional wiring board.

Explanation of symbols

1 is a heating element 2 is solder 3 is a first metal layer 4 is a second metal layer 5 is a first resin insulation layer 6 is a second resin insulation layer

Claims (3)

In the wiring board composed of a first resin insulating layer reinforced with a sheet-like fiber base material, a first metal layer and a second metal layer integrated on both sides thereof, and at least the first metal layer has a function of electrical wiring, A heating component is mounted on the electrical wiring of the first metal layer,
The total thickness of the first metal layer and the second metal layer is set to be thicker than the thickness of the first resin insulation layer, and the edge of the first metal layer is located inside the periphery of the first resin insulation layer,
The thermal expansion coefficient in the planar direction of the first metal layer is smaller than the thermal expansion coefficient in the planar direction of the second metal layer, and the thermal conductivity of the first metal layer is set higher than the thermal conductivity of the second metal layer,
A reinforcing fiber-filled second resin insulating layer that is in contact with the entire periphery of the edge of the first metal layer and has a thickness equal to or greater than the first metal layer thickness is added to the first resin insulating layer,
The wiring board, wherein the first resin insulating layer is a highly heat conductive insulating layer formed of an insulating material having a higher thermal conductivity than the second resin insulating layer.   The wiring board according to claim 1, wherein the first resin insulating layer has a thermal conductivity of 4 W / m · K or more.   The wiring board according to claim 1, wherein the thermal expansion coefficient in the planar direction of the second resin insulating layer is smaller than the thermal expansion coefficient of the first metal layer.

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