JPS60163492A - Substrate for heat sink 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 [Technical Field of the Invention] The present invention relates to the improvement of heat dissipating printed wiring boards used in electronic devices, etc. The present invention relates to a heat dissipating printed wiring board.

[Technical background of the invention and its problems] In recent years, electronic devices incorporating ICs and LSIs have become smaller and more dense, and as a result, the processing of heat generated in circuits equipped with ICs and LSIs has become more difficult. This is an important problem that cannot be ignored in terms of design.

In order to solve this thermal problem, we used prepreg, which is based on an aluminum plate with excellent heat dissipation and machinability, or anodized aluminum plate, and a paper cloth base material impregnated with thermosetting resin. Various types of printed wiring boards have been studied in which metal foils for forming wiring are bonded together.

However, since aluminum plates have poor surface activity, it is very difficult to bond them to prepregs.

In other words, since the adhesion between the aluminum plate and the cured resin is weak in substrates using conventional aluminum plates that have been subjected to mechanical surface treatments such as chemical coating treatment, sandblasting, and honing, punching and drawing processes are not possible. At times, peeling occurs between the aluminum plate and the prepreg, resulting in a significant reduction in product yield.

[Object of the invention] The object of the present invention was made to eliminate the above-mentioned drawbacks, and has excellent adhesion between the aluminum plate and the cured resin.
The present invention aims to provide a heat dissipating printed wiring board with good machinability.

[Summary of the Invention] As a result of extensive research to achieve the above object, the present invention has revealed that if an aluminum plate is subjected to microwave discharge plasma treatment, the wettability with the prepreg will be improved and the adhesion will be improved. It has been discovered that a substrate with excellent machinability can be obtained. That is, in the present invention, the aluminum plate and metal foil subjected to microwave discharge plasma treatment are
This heat dissipating printed wiring board is characterized in that it is laminated with a prepreg formed by impregnating a paper cloth base material with a thermosetting resin and integrated under heating and pressure.

The aluminum plate treated with microwave discharge plasma used in the present invention transfers energy by using microwaves with a frequency of 109 to 10" Hz as electromagnetic field waves to accelerate electrons present in the gas and cause molecules and atoms to collide. Microwave discharge does not require a discharge electrode, so contamination from the electrode can be prevented, and microwave power can be locally injected into the external space. A high-density plasma can be generated due to low radiation loss, the discharge can be stable over a wide gas pressure range, the magnetron used for oscillation is simple and has a long life without the need for an amplifier, and it is transmitted using a waveguide. Therefore, it has characteristics such as no radiation loss and easy matching.A microwave discharge plasma device (not shown) includes a microwave oscillation section, its transmission circuit, a plasma generation section that performs discharge, It is composed of an exhaust device that transports and exhausts gas, a gas supply section, etc. Generally, microwaves with an output of 100 W to 10 kW are transmitted to a plasma generating section in a waveguide to generate plasma.

The exhaust device is used to transport radicals generated in the discharge plasma generating section to the processing chamber and to degas the system before discharge.
Further, as the raw material gas, usually air, oxygen gas, argon gas, helium gas, etc. are used. The discharge plasma created in this way contains electrons, ions, excited molecules, radicals, ultraviolet light, etc., so if an aluminum plate is exposed to this, the surface will be chemically modified in an extremely short time. . The thickness of this modified surface layer is 1 μm or less, and it can improve the wettability with the prepreg and significantly improve the adhesion without impairing the aluminum properties. Further, conventional sandblasting, honing, etc. can be used in combination as necessary.

The metal foil used in the present invention is not particularly limited, but copper foil is usually used, and either electrolytic copper foil or rolled copper foil may be used, and the thickness thereof is not limited.

The prepreg used in the present invention is a paper fabric base material impregnated with a thermosetting resin and semi-cured.

Examples of the paper fabric base material used for this prepreg include cotton linter paper, kraft paper, mixed paper, glass cloth, glass vapor, and nonwoven fabric. Further, examples of the thermosetting resin to be impregnated into the paper fabric base material include phenol resins, epoxy resins, polyimide resins, and modified resins thereof.

The heat dissipating printed wiring board of the present invention can be easily manufactured as follows. An aluminum plate treated with microwave plasma and metal foil are passed through prepreg, which is made by impregnating a paper cloth base material with thermosetting resin, drying and semi-curing (one side of the prepreg is an aluminum plate treated with plasma, the other side is (metal foil) superimposed, 80-25
5~ at a temperature of 0℃, a pressure of 5~100ka/co+2
Manufactured by heating and laminating for 90 minutes.

[Effects of the Invention] The thus obtained heat dissipating printed wiring board of the present invention has excellent adhesion due to improved wettability between the aluminum plate and the prepreg, and is suitable for punching and drawing during the production of printed wiring boards. There is no peeling during machining, etc., and such product defects are significantly reduced, making it possible to improve yield.

[Examples of the Invention] Examples of the present invention will be described below, but the present invention is not limited to these Examples.

Example 1 Aluminum plate with a thickness of 1111Il (Al100P
-H24) after cleaning with Triclean, the microwave oscillation part is 2
450M)-1z, 1kW1 plasma gas is oxygen,
3 from a distance of 50 cm at a pressure of 101-orr.
Microwave discharge plasma treatment was performed for 1 minute. A glass cloth is impregnated with an epoxy resin containing a hardening agent on the treated surface of the aluminum plate and dried to a thickness of 0, 1+n.
m prepregs were superimposed, and then a 35 μm thick copper foil was superimposed on the prepregs, and the temperature was 150°C.
A heat dissipating printed wiring board was obtained by heating and pressurizing and laminating and integrating at a pressure of 30K (1/cm2) for 1 hour.

The punching workability and drawing workability of the obtained substrate were tested. The results are shown in Table 1.

Each test was conducted as follows.

Press punching workability is 50IIIIII at room temperature.
The copper foil of the sample press punched to a size of 70 mm was removed by etching, and the state of peeling between the aluminum plate and the prepreg was visually inspected, and any peeling even slightly was judged to be defective. In addition, the drawing processability is 20m1 as a simple method.
A sample press-punched to x 100+u was bent at 90 degrees so that the copper foil was on the outside, and any sample in which even a small amount of the glass cloth was peeled off from the aluminum plate was judged as defective. Both punching workability and drawing workability are expressed as the percentage of good products out of 150 samples.

Example 2 Except for using air as the plasma gas in Example 1, all the treatments were carried out in the same manner as in Example 1 to obtain a heat dissipating printed wiring board, and the test was conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative example 1 1 mm thick aluminum plate (A 1100P-H2
4) was washed with trichlene, sandblasted with 120 meshes, and washed again with trichlene. Using this, the same procedure as in Example 1 was carried out at 150°C and 30k (1/011
12. A heat dissipating printed wiring board was obtained by heating, pressing and laminating for 60 minutes. Characteristic tests were also conducted in the same manner, and the results are shown in Table 1.

Comparative Example 2 A 1 mm thick aluminum plate with a fluorine ion concentration of 0.5
%, a phosphate ion concentration of 6%, and a chromic acid concentration of 1.2%. After being immersed at 40°C for 1 minute in a chemical film treatment solution containing 6% phosphate ion concentration and 1.2% chromic acid concentration, washed with water and dried, a heat dissipating printed wiring board was prepared in the same manner as in Example 1. I got it. Characteristic tests were also conducted on the obtained substrate in the same manner, and the results are shown in Table 1.

As is clear from Table 1, the heat dissipating printed wiring board of the present invention was found to be superior in punching workability and drawing workability compared to the comparative example.

Patent applicant: Toshiba Chemical Corporation

Claims (1)

[Claims] 1. An aluminum plate treated with microwave discharge plasma and a metal foil are stacked together via a prepreg formed by impregnating a paper fabric base material with a thermosetting resin, and are integrated under heat and pressure. Heat-dissipating printed wiring board.