JP2005064168A - Metal-based circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-based circuit board which is kept high in both thermal conductivity and heat cycle durability. <P>SOLUTION: The metal-based circuit board is used for a hybrid integrated circuit including both an electronic part releasing much heat and an electronic part requiring high thermal shock durability. The metal-based circuit board is composed of a metal plate and an insulating layer formed on the one main surface of the metal plate, and the circuits are formed on the one main surface of the metal plate through the intermediary of the insulating layer. The insulating layer is equipped with one region formed of a high-thermal conductivity insulating layer and the other region formed of silicone resin having JIS A hardness of 90 or below, and it is preferable that the region formed of a high-thermal conductivity insulating layer is formed of epoxy resin loaded with a high thermal conductivity filler. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal base circuit board for a hybrid integrated circuit including both a highly exothermic electronic component and an electronic component requiring thermal shock durability.

A circuit board, particularly a metal base circuit board, has a structure in which a circuit is provided on one main surface of a metal plate via an insulating layer (see Patent Document 1 and Patent Document 2), so that the insulating layer has high thermal conductivity. As a result, the heat generated from highly heat-generating electronic components such as highly integrated ICs can be efficiently dissipated, and the mechanical strength is also excellent, so circuit boards for audio equipment, automobiles, etc. Are widely used in the industry as circuit boards for in-vehicle use and circuit boards for air conditioning equipment.

Japanese Patent Laid-Open No. 11-150345

Japanese Unexamined Patent Publication No. 11-8450

On the other hand, regarding the electronic components mounted on the circuit board, recently there has been considerable progress, and the electronic components mounted on the circuit board are also transitioning from the self-supporting type to the chip type with good mountability, Chip ICs (hereinafter referred to as IC chips) are used in various applications. Resistor chips, capacitor chips, etc. are mainly ceramic molds with a small coefficient of thermal expansion and good durability.

The IC chip is mounted on the circuit board via a heat sink. In this case, since the IC chip generates a lot of heat, the IC chip is usually mounted on the heat sink via a high-temperature solder. The heat sink is mounted on a circuit on a circuit board. Thus, chip components such as the IC-mounted heat sink, resistor chip, and capacitor chip are bonded and mounted at predetermined positions on the circuit on the circuit board by the solder paste.

  Due to the above circumstances, two or more types of insulating layers are provided on one main surface of a metal plate so that the metal base circuit board also has various characteristics, and different characteristics are achieved depending on the location of the same circuit board. An attempt is also disclosed (see Patent Document 3).

JP-A-6-90071

  As described above, the metal base circuit board is excellent in mechanical strength, and can efficiently dissipate heat generated from the mounted IC etc. by making the insulating layer highly thermally conductive. Widely used in industry as circuit boards, circuit boards for air conditioning equipment, etc., especially as automotive circuit boards for automobiles, which are evolving day by day, metal-based circuits due to weight reduction, rust prevention, and the pursuit of price As the metal plate used for the substrate, aluminum alloy or anodized is the best.

  As a metal base circuit board applied to the application, extremely high durability is required, and a heat cycle of 3000 cycles or more at a low temperature side of −40 ° C. and a high temperature side of 125 ° C. is required. However, in the conventionally known metal base circuit board, the solder part that joins the chip to the circuit after several hundred cycles due to the difference in expansion coefficient between the metal board and the resistor chip or the capacitor chip during the heat cycle. A metal base circuit board that can prevent a solder crack is strongly desired.

  The inventor of the present invention has been made to solve the above-mentioned problems of the state of the art as a concrete problem, and the purpose thereof is excellent in heat dissipation and thermal shock resistance, and thus in electrical reliability. An object of the present invention is to provide a metal base circuit board that is excellent in durability and durability.

The present invention relates to a metal base circuit board for a hybrid integrated circuit including both a highly exothermic electronic component and an electronic component that requires thermal shock durability, and the circuit is provided on one main surface of the metal plate via an insulating layer. And the insulating layer has a region composed of a high thermal conductivity insulating layer and a region composed of a silicone resin having a JIS A hardness of 90 or less, preferably, The metal base circuit board according to claim 1, wherein the region made of the high thermal conductive insulating layer is made of an epoxy resin filled with a high thermal conductive filler.

The present invention also includes (1) a step of applying a high thermal conductivity epoxy resin adhesive to a desired portion on one main surface of a metal plate, (2) a step of semi-curing the high thermal conductivity epoxy resin adhesive, (3) a step of applying a silicone adhesive to a portion of the metal plate on which the high thermal conductivity epoxy resin adhesive is not applied; (4) the semi-cured high thermal conductivity epoxy resin adhesive; A step of laminating a metal foil on the surface of the silicone adhesive and curing the high thermal conductivity epoxy resin adhesive and the silicone adhesive; and (5) a step of processing the metal foil to form a circuit. A method of manufacturing a metal base circuit board characterized by the following.

Since the metal base circuit board of the present invention has both a region made of an insulating layer excellent in heat dissipation and a region made of an insulating layer excellent in thermal shock durability, each of them has a heat generating electronic component and a thermal shock. By placing and using electronic components that require durability, hybrid integrated circuits with excellent electrical reliability and durability can be easily provided, so strict durability is required. It is extremely industrially useful as an in-vehicle circuit board and a household circuit board related circuit board with a long life and an industrial circuit board.

  The metal base circuit board manufacturing method of the present invention is extremely useful industrially because a metal base circuit board having the above-described characteristics can be easily obtained with high productivity.

  The metal base circuit board of the present invention is a metal base circuit board for a hybrid integrated circuit including both high heat-generating electronic components and electronic components that require thermal shock durability. Examples of the highly exothermic electronic component include an integrated circuit element and a power transistor, and examples of the electronic component requiring thermal shock durability include a resistor chip and a capacitor chip.

  In the metal base circuit board of the present invention, a circuit is formed on one main surface of a metal plate via an insulating layer, and the insulating layer has a region composed of a high thermal conductive insulating layer and a JIS A hardness of 90 or less. A metal base circuit board having a region made of silicone resin, and is shown in, for example, a hybrid integrated circuit illustrated in FIG. 1 described later.

  In the present invention, the metal plate (1) used for the metal base circuit board includes many materials such as aluminum and aluminum alloys, steel, stainless steel, copper, and titanium. From the viewpoint of weight reduction, adhesiveness, cost, etc., aluminum, aluminum alloy, or alumite of the metal surface is preferable. Furthermore, for example, for the purpose of adding a special function such as magnetism, a metal plate can be selected such as using a steel plate.

  The metal base circuit board of the present invention has a region (2) in which the insulating layer is composed of a high thermal conductive insulating layer. The material constituting the high thermal conductive insulating layer is electrically insulative. What is necessary is just to be comprised with resin, and also what added the electrically insulating inorganic filler to the said resin is more preferable from high thermal conductivity being obtained. Examples of the inorganic filler include alumina powder and aluminum nitride powder. These are used by filling 85 to 90% by mass in a resin.

The resin is preferably a low-viscosity liquid reactive resin because of the need to contain an inorganic filler, and examples thereof include silicone resins, epoxy resins, acrylic resins, and urethane resins. These resins are generally used as adhesives, and may be mixed for the purpose of improving characteristics. Among the resins, epoxy resin is a particularly preferable resin from the viewpoint of adhesion to a metal foil or a metal plate and durability as a circuit board. In particular, an insulating layer having a high thermal conductivity of 3 to 8 W / m · K can be formed by filling the epoxy resin with 85 to 90 mass% of alumina powder or aluminum nitride powder.

The metal base circuit board of the present invention is characterized by having a region 3 made of a silicone resin having a JIS A hardness of 90 or less. And, as described above, the metal base circuit board of the present invention,
There is a structural feature in which the insulating layer has a region made of a highly thermally conductive insulating layer and also has a region made of a silicone resin having a JIS A hardness of 90 or less. And because it has the above structural features, it is applied to a hybrid integrated circuit that has both heat-generating electronic components and electronic components that are required to have thermal shock durability, and hybrid integration that excels in electrical reliability and durability. This shows the effect that the circuit can be easily provided.

  As a result of various studies on the silicone resin used in the present invention, the present inventors have obtained the knowledge that the effects of the present invention can be obtained only when the silicone resin having the above characteristics is used. .

Silicone resin generally has a glass transition temperature of −40 ° C. or lower, and has a characteristic that characteristics are not deteriorated even at a high temperature of 260 ° C. that is received at the time of soldering in a stage where a hybrid integrated circuit is formed. I get the impression that any silicone resin is acceptable. However, based on the inventor's experimental investigation, the reason is unknown, but the flexibility of a silicone resin having a JIS type A hardness of 90 ° C. or less at 23 ° C., ie, a silicone resin obtained by curing a silicone adhesive, is JIS. It has been found that the effect of the present invention can be obtained when the type A hardness is 90 or less, and in the numerical range exceeding 90, the effect of the present invention cannot be sufficiently obtained.
The hardness of the silicone resin is a value measured with a JIS type A hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) after curing the silicone adhesive in a circular frame having a depth of 4 mm and a diameter of 3 cm.

  In the present invention, the thickness of the insulating layers (2, 3) is preferably 50 to 300 μm. As described above, in the present invention, both the region (2) composed of a high thermal conductive insulating layer and the region (3) composed of a silicone resin having a JIS A hardness of 90 or less are combined, and a metal foil ( In order to mount 4), both are inevitably the same thickness, but the thickness is a region (2) composed of a high thermal conductive insulating layer and a region composed of a silicone resin having a JIS A hardness of 90 or less. Depending on the characteristics to be possessed by (3), a specific range is desirable. With a thickness of less than 50 μm, withstand voltage characteristics may not be ensured, and with a thickness exceeding 300 μm, heat dissipation is poor. May cause problems in application development.

  In the present invention, for the purpose of improving the characteristics, the insulating layers (2, 2 ', 3) may have a multilayer structure as shown in FIG. Even in this case, it is desirable that the thickness of the silicone resin portion (3) having a JIS A hardness of 90 or less is 15 to 150 μm. This is because when the temperature deviates from the above range, sufficient thermal shock durability may not be ensured.

  The metal foil (4) used for this invention forms the circuit in a circuit board, and can use highly conductive copper, aluminum, etc., those alloys, composite foil. The copper foil may be either an electrolytic copper foil or a rolled copper foil, but since the copper foil product is usually treated with an imidazole-based rust preventive agent, it is preliminarily heated with high temperature or alcohol. Since the copper foil adhesion strength of silicone adhesives using platinum compounds as a curing catalyst increases dramatically when washed or diluted with copper etchant, it is preferable to treat the copper foil in advance. There is no need for a silicone adhesive that does not inhibit the catalytic action of the platinum compound or that does not use the platinum compound as a curing catalyst.

Next, the manufacturing method of the metal base circuit board of this invention is demonstrated.
The method for producing a metal base circuit board according to the present invention includes (1) a step of applying a high thermal conductivity epoxy resin adhesive to a desired portion on one main surface of a metal plate, and (2) the high thermal conductivity epoxy resin adhesive. (3) a step of applying a silicone adhesive to a portion of the metal plate on which the high thermal conductive epoxy resin adhesive is not applied, (4) the semi-cured high thermal conductivity A step of laminating a metal foil on the surface of the epoxy resin adhesive and the silicone adhesive and curing the high thermal conductivity epoxy resin adhesive and the silicone adhesive; (5) processing the metal foil to form a circuit; And a process for producing a metal base circuit board.

FIG. 1 and FIG. 2 are diagrams each showing a hybrid integrated circuit using a metal base circuit board according to the present invention. In the present invention, first, a metal plate (1) cleaned by a method such as degreasing is prepared, and a high thermal conductive insulating layer (on a desired portion on one main surface of the metal plate (1) is prepared. 2) Apply a high thermal conductivity epoxy resin adhesive so that it can be formed, semi-cure the high thermal conductivity epoxy resin adhesive by means of heating or the like, and then apply the high thermal conductivity epoxy resin adhesive A semi-cured highly heat-conductive epoxy resin is coated with a silicone adhesive so that an insulating layer (3) composed of a silicone resin having a JIS A hardness of 90 or less after curing is obtained on an unfinished metal surface. A metal foil is placed on the surface of the adhesive and the silicone adhesive, both resins are cured by means such as heating, and the metal foil is further processed by means such as etching to form a circuit (4). It is characterized by.

  By executing the operations in the order as they are, the metal base circuit board of the present invention shown in FIG. 1 can be easily obtained with high productivity. In FIG. 1, the metal base circuit board obtained by the above operation is used, and subsequently, a solder resist (5) is applied and cured at a predetermined position, and then the heat sink (6) is attached to the high thermal conductive insulating layer. An IC chip (7), which is a heat-generating component, is formed on the circuit (4) in the region via a solder paste, and a circuit (4) on the insulating layer (3) made of a silicone resin having a JIS A hardness of 90 or less. On the top, a resistor chip or a capacitor chip (9) is mounted with solder (10), and further, wire bonding (8) is performed to form a hybrid integrated circuit.

An aluminum plate having a thickness of 1.5 mm cut into 120 mm × 120 mm was immersed in an alkaline degreasing agent (Ecline manufactured by Riko Kyosan Co., Ltd.) at 50 ° C. for 1 minute, neutralized, washed with water, and then dried with hot air at 110 ° C. , Referred to as degreased aluminum plate).

A liquid epoxy resin (Epicoat 807 manufactured by Yuka Shell Co., Ltd.) is blended with an aromatic amine curing agent in a high thermal conductive epoxy resin in which 10 parts by mass of alumina powder (manufacturer, grade, particle size, etc.) is filled 90 parts by mass ( Hereinafter, 0.3 parts by mass of a surface improver (BIC Chemie Japan Co., Ltd. BYK) and 2 parts by mass of butyl cellosolve are added and mixed to adjust the viscosity (hereinafter referred to as “high heat”). (Hereinafter referred to as conductive epoxy adhesive ink), and applied to a desired portion of one main surface of the degreased aluminum plate at a thickness of 100 μm (hereinafter, printing application using a 15 GT printer manufactured by Neurong).

Next, after heating in an oven at 150 ° C. for 6 minutes and leaving to cool to 23 ° C., a silicone adhesive (SE-1701 manufactured by Toray Dow Co., Ltd.) was applied to the surface of the degreased aluminum plate to which the high thermal conductive epoxy adhesive ink was not applied. Then, a cured product JIS type A hardness 64) was applied to a thickness of 100 μm, and subsequently an electrolytic copper foil (manufactured by Furukawa Electric Co., Ltd.) having a thickness of 120 mm × 120 mm previously cut at 350 ° C. for 3 minutes in an oven. After the heat treatment, the cooled copper foil (hereinafter referred to as heat treated electrolytic copper foil) is placed on the surface of the high thermal conductive epoxy adhesive and the silicone adhesive, and hot pressed at 120 ° C. for 10 minutes for the adhesive. Cured. Further, it was taken out from the press and heated and cured in an oven at 150 ° C. for 10 hours to obtain a metal base substrate (hereinafter referred to as an aluminum base substrate).

<Peel strength> As a result of measuring the T-shaped peel with a tensile tester (tensile tester manufactured by Tensilon) under the condition of a peel rate of 50 mm / min by cutting the copper foil portion of the aluminum base substrate into a width of 1 cm. A peel strength of 20 N / cm was shown. The peel strength test piece of the aluminum base substrate was floated on a solder bath set at 260 ° C., allowed to stand for 10 minutes, cooled, and the peel strength was measured in the same manner as described above. As a result, there was no change in the peel strength.

<Withstand voltage> An etching resist is applied in a circular shape with a diameter of 2 cm on the copper foil portion of the aluminum base substrate, and after drying, the copper foil is etched with an aqueous solution of 10% by mass of ammonium persulfate. After washing and drying, the etching resist is removed. Thus, a test piece for withstand voltage measurement was prepared. Measure the breakdown voltage of the insulation layer by soldering a copper wire in the center of the circular copper foil and applying an AC voltage between the base aluminum plate and the copper wire in insulating oil (Fluorinert manufactured by Sumitomo 3M). (Withstand voltage measuring instrument TOS8700 manufactured by KIKUSUI) As a result, dielectric breakdown occurred at 5.8 KV. The withstand voltage test piece was floated on a solder bath set at 260 ° C., allowed to stand for 10 minutes, cooled, and the breakdown voltage was measured in the same manner as described above. As a result, there was no change in the breakdown voltage.

<High-temperature and humidity-resistant pressure cooker test> The peel strength test piece and the withstand voltage test piece were treated with a pressure cooker tester (manufactured by Alp, test temperature 121 ° C) for 100 hours, and the peel strength and dielectric breakdown voltage were measured. The strength was 20 N / cm, the dielectric breakdown voltage was 6.0 kV, and there was no change due to the treatment.

<Heat cycle test> After cleaning the metal foil of the aluminum base substrate, apply an etching resist in place, dry and etch to remove the etching resist, then apply a solder resist and cure I let you. Further, a solder paste (manufactured by Senju Metal Co., Ltd.) is applied onto the circuit, and a resistor chip (2125 manufactured by ROHM Co., Ltd.) and a capacitor chip (3225 manufactured by TDK Co., Ltd.) are mounted. The solder was melted to join the chips. Then, after removing the solder flux by ultrasonic cleaning with toluene, a heat cycle tester (LT-60S manufactured by Enomoto Kasei Co., Ltd.) holds the low temperature side at −40 ° C. for 7 minutes and the high temperature side at 125 ° C. for 7 minutes. As a result of carrying out the heat cycle test, no disconnection abnormality or the like due to the occurrence of solder cracks was found even after 5000 heat cycles.

<Measurement of thermal conductivity> As a result of curing a high thermal conductive epoxy adhesive to a thickness of 2 mm, cutting it into a 1 cm × 1 cm with a diamond cutter, and measuring the thermal conductivity by a laser flash method (FA8510B manufactured by Rigaku), The conductivity was 4 W / mK.

A high heat conductive epoxy adhesive ink was applied to the entire surface of a 1.5 mm thick degreased aluminum plate cut into 120 mm × 120 mm in a thickness of 50 μm. Next, after heating in an oven at 150 ° C. for 8 minutes, the mixture is allowed to cool to 23 ° C., and the above-mentioned high thermal conductive epoxy adhesive ink is applied to a thickness of 50 μm, heated at 120 ° C. for 20 minutes, and then cooled to 23 ° C. A silicone adhesive (SE-1701) was applied to a thickness of 50 μm. Subsequently, a 70 μm-thick electrolytic copper foil cut in advance of 120 mm × 120 mm was heated in an oven at 350 ° C. for 3 minutes and then cooled, and then the electrolytic copper foil was coated with a high thermal conductive epoxy adhesive ink and a silicone adhesive Installed on top. Next, the adhesive was cured by hot pressing at 120 ° C. for 10 minutes. Further, it was removed from the press and heated and cured in an oven at 150 ° C. for 10 hours to obtain an aluminum base substrate having a structure as shown in the hybrid integrated circuit diagram of FIG. As a result of evaluating the characteristics in the same manner as in Example 1, <Peel strength> The copper foil part of the aluminum base substrate was cut into a width of 1 cm, and T-shaped peeling was measured under the same conditions as in Example 1. As a result, 18 N / A peel strength of cm was shown. The peel strength test piece of the aluminum base substrate was floated on a solder bath set at 260 ° C., allowed to stand for 10 minutes, cooled, and peel strength was measured. As a result, there was no change in peel strength.

As a result of measurement in the same manner as in Example 1, the withstand voltage was 6.0 KV. Further, the dielectric strength test piece was floated on a solder bath set at 260 ° C., allowed to stand for 10 minutes, cooled, and the breakdown voltage was measured as described above. As a result, the breakdown voltage was not changed. The high temperature and humidity resistance pressure cooker test was measured in the same manner as in Example 1. As a result, the peel strength was 19 N / cm, the dielectric breakdown voltage was 6.0 kV, and there was no change due to the treatment. Furthermore, as in Example 1, chip components were mounted, flux washed, and heat cycle tests were conducted. As a result, no abnormalities in wire breakage due to the occurrence of solder cracks were found after 5000 heat cycles. One point out of 10 substrates on which apparent fine lines were observed was observed. Furthermore, the result of measuring the thermal conductivity in the same manner as in Example 1 was 4 W / mK.

Except for replacing the silicone adhesive of Example 1 with 74 parts by mass of alumina and 26 parts by mass of a silicone adhesive (SE-1700 manufactured by Toray Dow Co., Ltd.), an alumina-filled silicone adhesive (cured product JIS type A hardness 90). In the same manner as in Example 1, an aluminum base substrate was obtained. As a result of evaluating the characteristics of the aluminum base substrate in the same manner as in Example 1, the peel strength of the insulating layer portion in the region made of silicone resin is 15 N / cm, the peel strength of the insulating layer portion in the region made of high thermal conductive epoxy resin is 20 N / cm, The chip-bonded solder part was not disconnected at a withstand voltage of 5.6 kV and a heat cycle of 3000 cycles.

An aluminum base substrate was obtained in the same manner as in Example 2 except that the silicone adhesive in Example 2 was replaced with a silicone adhesive (SE-9207 manufactured by Toray Dow, JIS type A hardness 4).
As a result of evaluating the characteristics of the aluminum base substrate in the same manner as in Example 1, the peel strength of the insulating layer portion in the region made of silicone resin was 9 N / cm, the peel strength of the insulating layer portion in the region made of high thermal conductive epoxy resin was 20 N / cm, The chip bonding solder was not disconnected even at a withstand voltage of 5.4 kV and a heat cycle of 5000 cycles.
(Comparative Example 1)

A high thermal conductive epoxy adhesive ink is applied to a 100 μm thickness on a degreased aluminum plate, heated at 150 ° C. for 6 minutes, and after cooling, a 70 μm thick electrolytic copper foil cut into 120 mm × 120 mm is installed, Press to cure the adhesive. Further, the aluminum base substrate was obtained by removing from the press and heating and curing in an oven at 150 ° C. for 10 hours.

As a result of evaluating the characteristics of the aluminum base substrate in the same manner as in Example 1, the peel strength, the withstand voltage, and the thermal conductivity of the insulating layer were the same as in Example 1, but the heat cycle was 120 cycles, and the solder portion of the chip joint portion A crack occurred and the wire was broken.
(Comparative Example 2)

Instead of the silicone adhesive (SE-1701, JIS type A hardness 64) of Example 1, 90 mass parts of alumina and viscosity adjustment were added to a silicone adhesive (SE1700, cured product JIS type A hardness 46 manufactured by Toray Dow). For this purpose, a silicone adhesive ink blended with 6 parts by mass of toluene was applied, heated at 40 ° C. for 3 hours, cooled, and heat-treated electrolytic copper foil was placed thereon and hot pressed to cure the adhesive. Thereafter, the same processing as in Example 1 was performed to obtain an aluminum base substrate. The JIS type A hardness of the alumina high-filled silicone adhesive cured product was 100, and the thermal conductivity was 3.6 W / mK.

As a result of evaluating the characteristics of the aluminum base substrate in the same manner as in Example 1, the dielectric strength was 5.6 kV and the peel strength of the insulating layer portion in the region made of the high thermal conductive epoxy resin was 20 N / cm. The peel strength of the insulating layer portion was as low as 5 N / cm, and cracks were generated in the chip bonding solder after 500 heat cycles, resulting in disconnection.

  The present invention is, for example, an in-vehicle circuit board for automobiles and the like that is required to have severe performance and durability performance, particularly as an electronic control circuit board in an engine room, a circuit board for high-power acoustic equipment, and industrial use. Various applications such as circuit boards for air conditioning equipment can be made.

The figure of the hybrid integrated circuit which uses an example of the metal base circuit board based on this invention. The figure of the hybrid integrated circuit which uses another example of the metal base circuit board based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal plate 2 High heat conductive insulating layer 3 Insulating layer which consists of silicone resin whose JIS A hardness is 90 or less 4 Circuit 5 Solder resist 6 Heat sink 7 IC chip 8 Bonding wire 9 Resistor chip or capacitor chip 10 Solder

Claims (3)

A metal-based circuit board for a hybrid integrated circuit including both a highly exothermic electronic component and an electronic component requiring thermal shock durability, wherein a circuit is formed on one main surface of the metal plate via an insulating layer. The metal base circuit board is characterized in that the insulating layer has a region made of a high thermal conductivity insulating layer and a region made of a silicone resin having a JIS A hardness of 90 or less. 2. The metal base circuit board according to claim 1, wherein the region made of the high thermal conductive insulating layer is made of an epoxy resin filled with a high thermal conductive filler. (1) A step of applying a high thermal conductivity epoxy resin adhesive to a desired portion on one main surface of the metal plate, (2) a step of semi-curing the high thermal conductivity epoxy resin adhesive, (3) of the metal plate A step of applying a silicone adhesive to a portion of the main surface where the high thermal conductivity epoxy resin adhesive is not applied; (4) a surface of the semi-cured high thermal conductivity epoxy resin adhesive and the silicone adhesive; A metal base comprising: laminating a metal foil thereon and curing the high thermal conductive epoxy resin adhesive and the silicone adhesive; and (5) processing the metal foil to form a circuit. A method of manufacturing a circuit board.

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