JPS59204296A - Board for printed circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to an electrically insulating substrate with good thermal conductivity used for proboscises, heat sinks, etc. in the electronic industry.

(2) Description of background technology The electrically insulating board usually has a structure in which a resin layer is pasted on a metal plate, and a Cu foil is pasted on the resin layer to mask the entire area of the Cu foil that will become the printed circuit. Cu exposed outside the mask
The foil is dissolved and removed by etching or the like to form a printed circuit. Furthermore, instead of using Cu foil, it is also possible to use a conductive paste or the like on the resin layer and to form a printed circuit by etching it in the same manner. All the various components such as transistors, diodes, resistors, and capacitors are mounted on the printed circuit thus formed. This is called implementation. Since these parts generate heat, the electrically insulating substrate needs to have heat discharge properties, and of course also needs to have electrical insulation properties.

(3) Explanation of the prior art and its problems Conventionally, substrate materials such as printed wiring boards and heat sinks have been made of organic polymer materials and base materials such as paper-based phenol resin laminates or glass-based Nigeki resin laminates. Composites such as aluminum and ceramic materials such as alumina substrates are used, but both have low thermal conductivity and insufficient heat dissipation, so they are not suitable for ICs and MSs.
There was a drawback that high heat generation components such as I and LSI could not be arranged (mounted) at high density.

Therefore, efforts have been made to develop substrates made of metal, which has excellent heat resistance and thermal conductivity. For substrates based on metal, an electrically insulating layer is essential for forming a printed circuit, and it is important that this electrically insulating layer does not completely reduce thermal discharge properties. Therefore, composite laminates of metal and organic polymer materials, or composite substrates of metal and ceramic with an electrically insulating alumite film formed on an aluminum plate, etc., have been developed. The latter has drawbacks such as cracking in the alumite film and poor electrical insulation when the temperature of the alumite film increases. In order to reduce the thermal resistance of the former, a composite laminate in which fillers such as At203°5i02 and BN are completely mixed in the organic polymer material has been developed, but the reduction in thermal resistance is insufficient. The present applicant has previously proposed an electrically insulating substrate in which a film in which polyhedral metal oxide particles with a shape factor of 1 to 14 and all smooth surfaces are dispersed in an organic polymer is provided on aluminum or the like ( JP-A-56-35494). However, such polyhedral metal particles can only be obtained by a special manufacturing method, so they have the disadvantage of being expensive.

Furthermore, it is known to incorporate glass fibers into organic polymers, as disclosed in Japanese Patent Application Laid-open No. 57-56988 and Japanese Patent Application Publication No. 57-155794.・Thermal conductivity of the resin layer decreases.

(4) Purpose of the Invention The purpose of the present invention is to improve the thermal conductivity of a composite substrate of metal and organic polymer.

(5) Structure of the Invention The present invention is a printed circuit board having an insulating layer on a metal plate, and the insulating layer is made of an organic polymer made of metal particles coated with a metal oxide. shall be.

Hereinafter, the present invention will be explained with reference to all the drawings.

FIG. 1 schematically shows the entire cross section of the substrate of the present invention.
Reference numeral 1 denotes a metal plate, for example an aluminum plate, which may be anodized although not shown. Reference numeral 2 denotes an insulating layer made of an adhesive organic polymer, in which metal particles 3 coated with a metal oxide (hereinafter referred to as coated metal particles 3) are present. 4 is ordinary Cu foil, etc. 1. As the metal &], in addition to aluminum, copper, silver, nickel, titanium, etc., which have high thermal conductivity, can be used, but due to price, amount of N, etc., aluminum or this It is most preferable to use alumite treatment. The thickness of these metal plates 1 is usually 0.5 to 3+++ m. As the adhesive molecule used in the insulating layer 2, resins such as epoxy and phenol, rubber-like substances such as silicone rubber, etc. can be used.

The greatest feature of the present invention is that the coated metal particles 3 are used as a component of the insulating layer 2, and the metal part (core) of the coated metal particles contributes to improving heat dissipation, and the oxide part Since the (coating layer) is submerged in the core so that the metal part does not participate in electrical conduction, good thermal conductivity and good electrical insulation are achieved at the same time.

If the amount of coated metal particles dispersed in the organic polymer is too small, the thermal conductivity will be poor, and if it is too large, it will be difficult to form a strong insulating layer film. The proportion of particles is 10-70% by volume, preferably 2
It is 0-60%.

However, within a range that does not deteriorate the strength of the insulating layer film formation, an amount equivalent to 2 to 30 layers of the above 10 to 70% volume ratio is usually commercially available, such as ceramic or fine powder (for example, hexagonal BN It is also possible to form the insulating layer 2 by adding fine particles of BeO, 5i (32) and having a smaller particle size than the edge coating metal particles 3 and interposing them between the edge coating metal particles 3.

The thickness of the insulating layer 2 varies depending on the purpose of use, etc., but generally 0.01 to 0.1 - is suitable. Note that the thinner the male vein layer 2, the better the thermal conductivity, and the worse the insulation layer. Further, the diameter of the insulating layer 2 is approximately equal to the diameter of the coated metal particles 3,
It is possible to range from a state in which they are arranged in a uniform arrangement in an organic polymer to a state in which they are randomly arranged in multilayer fractions. In this case, naturally, the coated metal particles 3 also come into contact with each other. Since the coated metal particles 3 in the second aspect of the present invention have high thermal conductivity, a heat transfer path is formed by contact between the particles, contributing to improved heat conduction.

FIG. 2 is a diagram schematically showing the entire cross section of a coated metal particle. Here, 5 is a metal particle and 6 is a metal oxide particle. The metal particles 5 are fine particles made of copper, aluminum, silver, nickel, etc. and have a spherical shape or any other shape. If this metal particle is 5-19 mm thick, the insulating layer will inevitably become thicker, so
Generally, a thickness of about 100 microns or less, particularly about 30 microns or less, is suitable. Kagen 1 So compound 6 is At203. MgO
・At203. Floating types such as mullite and forsterite generally have a diameter of about 0.5 to 10 microns. Such coated metal particles 3 are produced by mixing the <1> group particles 5 into a dazzling powder and pressing at high speed.

All of these metal particles 5 are well mixed in the above-mentioned organic molecules.
1 Disperse, add all hardening agents, etc., and make ``V-1 printing method%''
Apply on one side or both sides of the V-koyoshi metal plate, dry,
Let it harden.

(6) Implementation ψ1" Example 1 75N parts of copper particles of 5 to 20 microns and an average particle size of 0.
Coated metal particles coated with 25 parts by weight of 5 micron alumina powder and a 5 micron layer of alumina were obtained. The coated metal particles were completely cured at 150° C. for about 1 minute.

50 mjt parts of the coated metal particles thus prepared were coated with 00 parts by weight of epoxy resin, thoroughly stirred, and coated on a 35 μm thick copper foil to a thickness of about 80 μm to prepare the entire adhesive layer. Then, it was placed on a blast-treated aluminum plate with a thickness of 1.5 mm and bonded under heat with a heated roll to create an aluminum base and copper cladding.

In the same manner, the thermal resistance was measured for cases in which AL206 particles of 10 μm or less were added as a total filler and cases in which no engraving was added. The dimensions of the board were 50 x 50 holes in the center, leaving the throat part (l x l 5 μs) by etching, and one run was made using all the heat dissipating solder of the 'l'(J-220" transistor). The measurement was performed with the substrate fixed to an ideal heat sink.

All measurement results are shown in the following table.

, bottom margin Table 1 Temperature rise rate (unit 'c,'w) In the table, Tj is the transistor junction temperature, Ps is the Inkaro power.

From Table 1, it can be seen that the printed circuit board of the present invention has a lower temperature increase rate than the comparative example.

(7) Effects According to the present invention, the thermal conductivity is improved compared to the conventional printed circuit board in which the entire ceramic powder is simply contained in the polymer.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a printed circuit board according to the present invention, and FIG. 2 is a schematic sectional view of coated metal particles. DESCRIPTION OF SYMBOLS 1...Metal plate, 2...Insulating layer, 3...Metal particles, 5...Metal particles, 6...Metal oxide. Patent applicant Showa Denko Co., Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Taku Murai Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. A printed circuit board comprising an insulating layer provided on a metal plate, wherein the insulating layer is made of an organic polymer containing metal particles coated with a metal oxide.