JPS5877295A - Heat sink board - 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 The present invention relates to a heat dissipation board for a high power circuit in which circuit elements that consume a large amount of power and generate a large amount of heat must be incorporated.

Conventional high-power circuits are made by forming conductors on an insulating substrate such as a ceramic plate or glass plate by screen printing or vapor deposition, and then adding passive circuit elements such as resistors and capacitors and active circuit elements such as transistors as appropriate. It was formed by adhesion.

However, in the above configuration, since the substrate is an insulating material such as ceramic glass, heat dissipation is poor, and when resistors and transistors designed for high power are incorporated, the resistors and transistors generate a large amount of heat. There is a risk that the heat may destroy not only peripheral components such as capacitors, but also resistors and transistors themselves. Moreover, even if it does not result in destruction, it often causes a significant change in the electrical characteristics. To counter this and improve reliability, it was often the case that a large aluminum heat sink was separately fabricated and installed between the conductor and the circuit element to prevent the temperature of the circuit element from rising.

Alternatively, in order to effectively dissipate heat, an aluminum metal plate is used, and the entire surface of the aluminum plate is anodized to form an aluminum oxide film, which is used as an insulating substrate. However, in this case, the aluminum oxide film is very sensitive to heat and cracks at 120°C, and cracks also occur at a temperature difference of 110°C. Therefore, electrical insulation becomes a big problem. As a measure against electrical insulation, some have coated a resin on the aluminum oxide film, but the resin layer deteriorates heat dissipation. Insulating substrates are also used in which a resin layer is provided directly on the entire surface of an aluminum plate, but due to the problem of the resin layer's bin holes and its electrical insulation properties, the resin layer is naturally thick and has very poor heat dissipation. .

In addition, conventional conductors on insulating films are formed by coating and curing a conductor material using a screen printing method, by mask deposition using a vapor deposition method, by electroless plating, or by forming a conductor material using a copper foil. The method is to attach it with adhesive and then etch it into a pattern, which increases the number of man-hours and is complicated.

As described above, the conventional heat dissipation board is unsuitable as a heat dissipation board for a high power circuit in which a circuit element that consumes a large amount of power and generates a large amount of heat must be incorporated, and has many drawbacks.

The present invention solves the above-mentioned drawbacks by effectively dissipating the heat generated from resistors and transistors, and providing excellent electrical insulation.
The present invention is intended to provide a heat dissipation board that has a simple structure and can be mass-produced.The present invention will be described in detail below with reference to the drawings.

The structure of the heat dissipation board of the present invention is as shown in FIGS. 1 and 2. A treatment agent in which silicon oxide is stably dispersed in a varnish made of silicone resin and a solvent is applied and hardened on at least one surface of an aluminum plate 1. An insulating film 2 is formed (so-called Pesta treatment using the Vesta treatment agent of the Dow Corning Company method), and on the film 2 /? It is formed by adhering and forming a flexible printed wiring JL layer 3 formed into turns.

The heat dissipation board of the present invention constructed in this way has very good heat resistance because it is coated with a PESTA treatment agent in which silicon oxide is stably dispersed in a varnish made of silicone resin and a solvent. Whereas the conventionally used aluminum oxide film only cracks when heated to about 120°C, no cracking occurs even after heating at 350°C for 10 minutes. Thermal shock resistance is also extremely high, approximately 110°C in the case of aluminum oxide film only.
The film cracks due to a temperature difference of 20°C, but even if the film is heated at 300°C for 10 minutes and then immediately immersed in water at 20°C, no film cracking occurs. In addition, any coating method such as dip method, spray method, or electrostatic coating method can be used. Even after 500 hours of immersion, no blackening occurs and it shows excellent hot water resistance.

When the Pesta-based film is coated using the dip method, 1
A film thickness of 4 to 6 μm can be obtained in one treatment. Since the film thickness can be reduced in this way, when resistors and transistors are incorporated, the heat generated from the resistors and transistors is transmitted to the aluminum plate and dissipated into the outside air. Since the flexible printed wiring board with the turns formed thereon is directly adhered onto the insulating film 2, the conductor 5 can be easily obtained; It has the advantage that the etching process can be omitted and the aluminum plate is not corroded by the etching solution (the corroded part in this case refers to the aluminum surface on which no insulating film is formed).

Another advantage is that it can be pre-treated with a conventional etching solution and stored in roll form. In addition, the patterned flexible printed wiring board can be bent into a roll shape and adhered to the board, so it is excellent in mass production.

In addition, because the structure of the aluminum plate 1, the film 2 formed by PESTA treatment, and the flexible printed wiring board 3 has double insulation film layers, the board has sufficient voltage resistance required for high power applications. It has excellent electrical insulation. Furthermore, since the film formed by PESTA treatment can be formed extremely thinly,
Even when heat generating circuit elements such as resistors and transistors are incorporated, the heat can be immediately transferred to the aluminum plate and dissipated to the outside air.

As described above, the heat dissipation board of the present invention is obtained by performing PESTA treatment on the entire surface of an aluminum plate to obtain an insulating film, and then adhering a flexible printed wiring board with /IP turns formed on the insulating film. This structure is extremely simple and can be easily formed with a uniform thickness. Furthermore, it has excellent electrical insulation properties and has a large heat dissipation effect, so it can be used as a heat dissipation board for high power circuits that require incorporating circuit elements that consume large amounts of power and generate large amounts of heat.

Examples of the present invention will be described below.

Example 1 The aluminum plate 1 explained in FIG. 1 has a thickness of 2.0 m.
, 20 cm long and 10 cm wide was used.

After degreasing the aluminum plate 1 with acetone, it was immersed in a 10% sodium hydroxide solution for 3 minutes.

This is washed with pure water, immersed in concentrated nitric acid for 1 minute, thoroughly washed with pure water, and dried to obtain an aluminum material.

Next, a Pesta treatment agent from Dow Corning was applied by the Ditsuno method and cured at 150° C. for 30 minutes to form a Pesta treatment film (about 5 μm thick) 2.

In addition, a flexible printed wiring board (25μ thick polyimide film, copper-clad on one side, size 20c+ys) was prepared in advance.
Prepare X10crn)3. Etching resist ink was printed in a pattern on the surface of the copper foil using a screen printing method, and was cured at 90 tl for 10 minutes. The etching resist ink is an alkali-soluble etching resist ink (commercially available from Mesh Kogyo Co., Ltd. (DNAZ-DA).
Next, the copper foil portions on which the etching resist ink was not printed were etched away by immersion in a known etching solution (ferric chloride hydrochloric acid solution commercially available from Yoshitani Shokai Co., Ltd.) for 10 minutes.

Furthermore, the etching resist ink was dissolved and removed by immersion in a 3-triple sodium hydroxide aqueous solution, followed by washing with water and drying. In this way, a flexible printed wiring board 3 was obtained.

After that, a thin layer of epoxy adhesive 4 (approximately 10 to 20 μm in thickness) was applied to the film 2 formed by Vesta treatment on the aluminum plate 1, and a flexible Norint wiring board was laminated thereon, and the epoxy adhesive was applied to the film 2 at 160° C. The heat dissipating substrate of the present invention could be obtained by curing within minutes.

Example 2 This will be explained with reference to FIG.

Obtain an aluminum material by the same method as in Example 1 ◎Next,
Using Dow Corning's PESTA treatment agent, it is applied to the aluminum plate 1 by the Ditsuno method (coating thickness: 5 μm).

Next, before curing, the flexible Norint wiring board 3 obtained by the same method as in Example 1 is laminated onto the applied PESTA treatment agent.Then, it is cured at 150°C for 30 minutes to obtain the heat dissipation board of the present invention. I was able to get However, in this case, because the Pesta treatment agent was applied using the Di J7'' method,
An uncured film is formed on both surfaces of the aluminum plate 10. Therefore, a release film was applied to the opposite side to which the flexible printed wiring board was to be laminated.

In this way, Example 1. Peripheral parts such as resistors, transistors, and capacitors were attached to the heat dissipation board obtained in Example 2, a high power circuit board was assembled, and its heat dissipation characteristics were investigated. The results are shown in Figure 3. OA is a paper phenol board, B
is a glass epoxy plate, C is a ceramic plate, D is a conventional aluminum plate, and E is a heat dissipation board of the present invention.

As described above, the heat dissipation board of the present invention effectively dissipates the heat generated from resistors and transistors, has good electrical insulation, has a simple structure, is suitable for mass production, and has practical value. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of Example 1 of the present invention, FIG. 2 is a cross-sectional view showing the structure of Example 2 of the present invention, and FIG. 3 is a diagram showing the heat dissipation characteristics of various substrates. DESCRIPTION OF SYMBOLS 1... Aluminum plate, 2... Insulating film by Vesta treatment, 3... Flexible printed wiring board, 4...
Adhesive, 5... conductor. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A treatment agent in which silicon oxide is stably dispersed in a varnish consisting of a silicone resin and a solvent is applied to at least one main surface of an aluminum plate and cured to form an insulating film, and a setane is formed on the film. 1) A heat dissipation board characterized by having a component wiring board adhered thereto.