JP3199599B2 - Metal-based multilayer circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based multi-layer circuit board, and more particularly to a metal-based multi-layer circuit board capable of mounting a heat-generating power electronic element and having excellent reliability.

[0002]

2. Description of the Related Art In recent years, high-density mounting and high performance have been required for a circuit board for mounting a semiconductor, and the heat generated from the semiconductor element has been increased due to the miniaturization, high performance, and fine wiring density of the semiconductor element. The problem is how to dissipate.

[0003] Therefore, a metal-based circuit board in which a conductive metal foil is adhered to a metal plate via an insulating layer is excellent in heat dissipation, and is used mainly in the field of power supplies. However, since the metal base circuit board has a structure in which a thin insulating layer is applied on a metal plate, the parasitic capacitance is nearly one digit larger than that of a commonly used glass epoxy board, and noise is likely to occur. For this reason, the electric circuit design becomes very complicated and has many restrictions.

As a countermeasure against this noise, a metal-based multilayer circuit board in which an insulating circuit board is laminated on a metal plate as an upper circuit board is disclosed (Japanese Patent Application Laid-Open Nos. 58-9399 and 5-327169). . However, the structures disclosed in JP-A-58-9399 and JP-A-5-327169 each include a metal plate or a metal plate coated with an insulating layer made of a resin containing an inorganic filler and an upper circuit board. Due to the structure of laminated glass epoxy substrates with poor heat conductivity, when mounting elements with high heat generation, heat dissipation is insufficient and the temperature of electronic elements rises,
As a result, there is a problem that a malfunction occurs.

[0005] In addition, there has been studied an insulating layer used for an upper circuit board, in which an insulating material filled with an inorganic filler is used to improve the thermal conductivity. Although the effect is recognized, it cannot be said that it is sufficient for a high heat-generating electronic element, and in addition, it is presumed to be expensive.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an excellent heat radiation property to prevent an increase in the temperature of an electronic component mounted on a circuit board.
An object of the present invention is to provide a metal-based multilayer circuit board having excellent reliability.

[0007]

According to the present invention, a circuit board and a high heat-generating electronic component are mounted on an insulating adhesive layer on a metal plate.
A metal-based multilayer circuit board, comprising:
Is provided directly on the insulating adhesive layer, and the
Electronic components are attached to the insulating adhesive layer via a high thermal conductive adhesive.
A metal base multilayer circuit board, characterized in that provided, also, which is the metal base multilayer circuit board having a metal layer between the insulating adhesive layer and the high thermal conductive adhesive.

Further, the present invention provides the metal-based multilayer circuit board, wherein the insulating adhesive layer is made of an epoxy resin containing any one of aluminum oxide, silicon oxide, and boron nitride. The circuit board is a metal-based multilayer circuit board, wherein at least two or more metal layers are laminated via an insulating adhesive.

The present invention will be described below with reference to the drawings. FIG.
1 is a cross-sectional view illustrating an example of a metal-based multilayer circuit board according to the present invention. FIG. 2 is a sectional view showing an example of the metal-based multilayer substrate according to claim 2 of the present invention. In FIG.
A circuit board 10 having metal layers 5A and 5B and partially having an opening has a structure in which the circuit board 10 is laminated on a metal plate 1 with an insulating adhesive layer 2 interposed therebetween. It is mounted on the layer 2 via a high thermal conductive adhesive 3.

FIG. 2 shows that a metal layer 6 having a larger heat transfer area than the high heat-generating electronic component 4 is formed on the insulating adhesive layer 2 located at the opening of the circuit board 10. The heat-generating electronic component 4 has a structure in which the heat-generating electronic component 4 is mounted via the highly heat-conductive adhesive 3, so that heat generated from the heat-generating electronic component 4 is more easily dissipated through the metal layer 6.
The metal layer 6 may or may not be formed with a circuit.

In the present invention, the high heat-generating electronic component 4 means a high-frequency transformer having a capacity of 200 VA or more / operating frequency of 200 kHz, a diode bridge having a capacity of 100 VA or more. The present inventors have found that when the above-mentioned high heat-generating electronic component is mounted on a multilayer circuit portion, the electric insulating layer existing between the circuits simultaneously acts as a heat insulating layer, so that heat dissipation is not sufficient, That the high heat-generating electronic component is connected to the metal plate 1
It has been found that the heat generated from the high heat-generating electronic component can be sufficiently dissipated only when the electronic component is arranged on the upper side, and the present invention has been accomplished. In addition, electronic components having a small heat value can be mounted on a multilayer circuit portion according to the characteristics required of the multilayer circuit board. As in the present invention, a high heat conductive adhesive is provided on the insulating adhesive layer 2. 3 can be mounted.

In the present invention, as described above, the high heat-generating electronic component 4 is disposed on the insulating adhesive layer 2 without the interposition of the circuit board 10, thereby promoting heat dissipation and reducing the temperature rise of the board itself. This suppresses the reliability of the entire metal-based multilayer circuit board and achieves a long life. A plurality of the high heat-generating electronic components may be mounted according to the characteristics required for the multilayer circuit board.

The insulating adhesive layer 2 is formed by applying a resin containing an inorganic filler onto a metal plate and then joining the metal layer to the metal layer by a pressing method or a laminator method. It is composed of an epoxy resin containing either silicon oxide or boron nitride. As the inorganic filler, those having excellent electric insulation and thermal conductivity and excellent filling properties into resin are selected.
A powder having a roundness of 50 μm or less and having an appropriate particle size distribution is used. Also, the higher the blending ratio, the better the thermal conductivity of the insulating adhesive layer. However, if the blending ratio is too high, bubbles may be involved in mixing with the resin, or the adhesiveness may deteriorate and the thermal conductivity may decrease rather. Therefore, usually 40 to 80% by volume is selected.

As the inorganic filler, aluminum oxide, beryllium oxide, silicon oxide, magnesium oxide, calcium oxide, boron nitride, silicon nitride, aluminum nitride and the like can be used. Of these, aluminum oxide, silicon nitride, and boron nitride are preferable because they provide an insulating adhesive having high thermal conductivity and high withstand voltage. In particular, when aluminum oxide or silicon oxide having a spherical particle shape is used, it is desirable because the resin can be highly filled and high thermal conductivity can be easily achieved economically. Aluminum oxide, silicon oxide, and boron nitride may be used alone or in combination of two or more depending on the characteristics required for the obtained metal-based multilayer circuit board.

As the resin, epoxy resin, polyimide resin, silicone resin, acrylic resin, phenol resin, bismaleimide triazine resin, various engineering plastics and the like are generally used. It is preferable because it has excellent insulation properties, adhesion to metals, and heat resistance.

Various types of epoxy resins are known, but modified with epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, butadiene / acrylonitrile copolymer having a terminal carboxyl group, and the like. A modified epoxy resin or a novolak-type epoxy resin such as phenol novolak or O-cresol novolak is particularly desirable in terms of electrical insulation, heat resistance, and the like.

Next, as the circuit board 10 of the present invention, a circuit board in which at least two or more metal layers 5A and 5B are laminated via an insulating adhesive layer 8 (hereinafter referred to as a double-sided resin board) is excellent in heat dissipation. It is preferred. However, depending on the characteristics of the desired multilayer circuit board, a circuit may be drawn on a rigid circuit board such as a glass epoxy resin circuit board, a phenol resin circuit board, a paper epoxy resin circuit board, or a polyimide resin board, in addition to the double-sided board resin board. Flexible circuit boards can be used. The thickness of these substrates is preferably 60 μm or less in order to improve heat dissipation.
It may also be used to improve response of the metal base circuit board comprising a surface of an electrically insulated metal plate as it is or needs.

The insulating adhesive 8 constituting the double-sided resin substrate
Is an electrically insulating material such as aluminum oxide, boron nitride, silicon oxide, magnesium oxide, aluminum nitride,
Moreover, it contains an inorganic filler having high thermal conductivity. Among the inorganic fillers, aluminum oxide, boron nitride, and silicon oxide are selected from the viewpoints of electrical insulation, thermal conductivity, and economy. Examples of the resin forming the insulating adhesive 8 include an epoxy resin, a polyimide resin, and a phenol resin, and an epoxy resin having a high adhesive strength to a metal is particularly preferable.

Examples of the high thermal conductive adhesive 3 of the present invention include epoxy resin, polyimide resin, silicone resin, acrylic resin, phenol resin, bismaleimide triazine resin, and various engineering plastics. Of these, epoxy resins, polyimide resins, bismaleimide triazine resins, and silicone resins are preferred because of their high electrical properties and excellent heat resistance. or,
The high heat conductive adhesive may contain an inorganic filler material such as aluminum oxide, silicon oxide, boron nitride, etc. as long as the adhesive performance is not reduced.

Examples of the metal plate 1 used for the metal-based multilayer circuit board of the present invention include aluminum and aluminum alloys, copper and copper alloys, iron and iron alloys, and copper / iron-nickel alloys / copper having good thermal conductivity. And a composite material such as aluminum / iron-nickel alloy / aluminum can be used. The thickness of the base metal plate 1 is not particularly limited, but is generally 0.5 mm to 3.0 mm.

The material of the metal layer 6 and the metal layers 5A and 5B may be any one of copper, aluminum, nickel, iron, tin, silver and titanium, or an alloy containing two or more of these metals and each metal. The used clad foil is used. The method of manufacturing the foil at this time may be an electrolytic method or a rolling method. Ni plating, Ni +
Metal plating such as Au plating or solder plating may be applied.

Hereinafter, the present invention will be described in more detail with reference to examples.

【Example】

Example 1 A glass epoxy circuit board (manufactured by Matsushita Electric Works Co., Ltd .; R-176) having a desired circuit drawn on a copper foil having a thickness of 35 μm on both sides and a glass epoxy material having a thickness of 60 μm.
6) was prepared and through holes were formed. Next, 510m
Bisphenol F type epoxy resin (manufactured by Yuka Shell Co .; Epicoat 807) containing 72 vol% of silicon oxide (manufactured by Denki Kagaku Kogyo KK) on an mx 510 mm x 1.5 mm aluminum plate Was used as an insulating adhesive, an amine-based curing agent was added, and the mixture was applied so as to have a thickness of 150 μm, and bonded and cured by heating. Using this original substrate, the substrate size is 100 × 150 mm, the output power is 1
A DC / DC converter with 50 W / operating frequency of 300 kHz was manufactured. The electronic control components are placed on the circuit on the glass epoxy circuit board in order to reduce the effect of the parasitic capacitance of the board.
(Capacity: 150 VA) was fixed on the insulating adhesive with a silicone adhesive. This device is placed in a room temperature of 25 ° C for 5 hours.
As a result of measuring the temperature of the back surface of the substrate at 112 ° C., the temperature was 112 ° C. During this time, the device operated functionally stably.

Example 2 An original substrate was prepared in the same manner as in Example 1. Using this substrate original, a substrate size of 1
00 × 150 mm, output power 150 W / operating frequency 30
A 0 kHz DC / DC converter was manufactured. The electronic control components are placed on the circuit on the glass epoxy circuit board to reduce the influence of the parasitic capacitance of the board, and the high heat generating component high-frequency transformer (made by TDK / capacity 150VA) is placed on the circuit on the insulating adhesive. Was fixed with a silicone adhesive. At this time, the high frequency transformer and the circuit pattern are electrically insulated. This device was operated for 5 hours in an environment at room temperature of 25 ° C., and the temperature of the back surface of the substrate was measured. As a result, the temperature was 107 ° C., and the device stably operated.

Example 3 Bisphenol A type epoxy resin having a desired circuit drawn on a copper foil with a thickness of 35 μm on both sides and containing 72% by volume of aluminum oxide (manufactured by Yuka Shell Co., Ltd .; Epicoat 828) was thermally cured with an amine-based curing agent to prepare a double-sided resin substrate having a thickness of 100 μm, and through holes were formed. Next, 510 mm x 51
A bisphenol F type epoxy resin containing 72% by volume of aluminum oxide was used as an insulating adhesive on an aluminum plate of 0 mm × 1.5 mm, an amine-based curing agent was added, and the mixture was applied to a thickness of 150 μm and heated by laminating. Cured. Next, a DC / DC converter having a substrate size of 100 × 150 mm, an output power of 250 W, and an operating frequency of 300 kHz was manufactured using this substrate plate. Electronic control components are placed on the circuit on the double-sided resin substrate to reduce the influence of the parasitic capacitance of the substrate, and a high-frequency heat-generating component high-frequency transformer (made by TDK / capacity 250 VA) is bonded to the insulating adhesive with silicon. It was fixed with the agent. This device is placed at room temperature 25
The device was operated for 5 hours in an environment of ° C., and the temperature of the back surface of the substrate was measured. As a result, the temperature was 108 ° C., and the device stably operated.

Example 4 A bisphenol F type epoxy resin having a desired circuit drawn on a copper foil with a thickness of 35 μm on both sides and containing 72% by volume of silicon oxide was thermally cured with an amine curing agent. Was prepared and a through hole was formed. Next, 510mm × 5
A bisphenol F-type epoxy resin containing 36% by volume of silicon oxide and 36% by volume of boron nitride is used as an insulating adhesive on a 10 mm × 1.5 mm aluminum plate, and an amine-based curing agent is added to make a thickness of 150 μm. And heat-cured together. Using this base plate,
A DC / DC converter having a substrate size of 100 × 150 mm, output power of 250 W / operating frequency of 300 kHz was manufactured. The electronic control components are arranged in a circuit pattern on a double-sided resin substrate in order to reduce the influence of the parasitic capacitance of the substrate.
VA) was fixed on the circuit on the insulating adhesive with a silicone adhesive. This device was operated for 5 hours in an environment at a room temperature of 25 ° C.,
As a result of measuring the temperature of the back surface of the substrate, the temperature was 105 ° C., and the device stably operated.

Comparative Example 1 A glass epoxy circuit board having a desired circuit drawn on a copper foil having a thickness of 35 μm on both sides and a glass epoxy material having a thickness of 60 μm was prepared and through holes were formed. Next, 510 mm x 510 mm x 1.5
A bisphenol F-type epoxy resin containing 72% by volume of silicon oxide was used as an insulating adhesive on an aluminum plate having a thickness of 150 mm, an amine-based curing agent was added, the mixture was applied to a thickness of 150 μm, and bonded and heat-cured. Using this substrate plate, a substrate size of 100 × 150 mm and an output power of 1
A DC / DC converter with 50 W / operating frequency of 300 kHz was manufactured. The electronic control parts were arranged on a circuit on a glass epoxy circuit board, and a high-frequency heat-generating high-frequency transformer (TDK / capacity 150 VA) was also fixed on the glass epoxy circuit board with a silicon adhesive. The apparatus was operated for 5 hours in an environment at room temperature of 25 ° C., and the temperature of the back surface of the substrate was measured.

Comparative Example 2 Bisphenol F type epoxy resin having a desired circuit drawn on a copper foil of 35 μm thickness on both sides and containing 72% by volume of silicon oxide was thermally cured with an amine curing agent. Was prepared and a through hole was formed. Next, 510mm × 5
A bisphenol F-type epoxy resin containing 72% by volume of silicon oxide was used as an insulating adhesive on a 10 mm × 1.5 mm aluminum plate, and an amine-based curing agent was added.
It was applied so as to have a thickness of 0 μm, and was laminated and cured by heating. Using this substrate original, a substrate size of 100 × 15
A DC / DC converter of 0 mm, output power 250 W / operating frequency 300 kHz was manufactured. The electronic control components are arranged in a circuit pattern on a double-sided resin substrate, and a high-heat-generating electronic component, a high-frequency transformer (manufactured by TDK Corporation / capacity: 250 V)
A) was also fixed on the upper layer circuit of the double-sided resin substrate with a silicone adhesive. The apparatus was operated for 5 hours in an environment at room temperature of 25 ° C., and the temperature of the back surface of the substrate was measured.

The results of Examples 1 to 4 and Comparative Examples 1 and 2 are listed in Table 1.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to prevent an increase in the temperature of electronic components mounted on a circuit board due to excellent heat dissipation.
A highly reliable metal-based multilayer circuit board can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a metal-based multilayer circuit board according to the present invention.

FIG. 2 is a sectional view showing another example of the metal-based multilayer circuit board of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal plate 2 insulating adhesive layer 3 high heat conductive adhesive 4 high heat-generating electronic component 5A, 5B metal layer 6 metal layer 7 control IC element 8 substrate of circuit board (insulating adhesive layer of double-sided resin board) 9 heat generation Electronic component 10 Circuit board 11 Wire for bonding

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 1/05 C09J 163/00 H05K 1/18

Claims (4)

(57) [Claims] 1. A circuit board on an insulating adhesive layer on a metal plate.
Metal-based multilayer circuit board with high heat-generating electronic components
Wherein the circuit board is directly on the insulating adhesive layer
The high heat-generating electronic component is provided with a high heat conductive adhesive.
A metal-based multi-layer circuit board, wherein the metal-based multi-layer circuit board is provided on the insulating adhesive layer . 2. The metal-based multilayer circuit board according to claim 1, wherein a metal layer is provided between the insulating adhesive layer and the high thermal conductive adhesive. 3. The metal-based multilayer circuit board according to claim 1, wherein said insulating adhesive layer is made of an epoxy resin containing any one of aluminum oxide, silicon oxide, and boron nitride. 4. The metal-based multilayer circuit board according to claim 1, wherein the circuit board has at least two metal layers laminated via an insulating adhesive.