JPS60214953A - Metallic base printed wiring substrate - 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] The present invention relates to a printed wiring board based on a metal plate.

1. Background Art] Printed wiring boards based on steel plates and other metal plates have recently come into widespread use as substrates for printed wiring boards used in electrical and electronic equipment. This metal-based printed wiring board has excellent properties such as heat dissipation effect due to the base metal plate and magnetic constant effect, and the base metal plate can also be used as a device case to make the device smaller. It also has the advantage of being able to

However, with printed wiring boards based on metal plates, corrosion such as rust easily occurs on the exposed parts of the metal plates, and this corrosion causes peeling of the insulating resin layer, which tends to reduce reliability. It was something that I had. In addition, when such a metal-based printed wiring board is press-cut, sag occurs on the cut end surface, and this sagging causes peeling of the insulating resin layer, and as this peeling progresses, the printed wiring board There is also the problem that the reliability of the system will be reduced. This problem can be solved by selecting the pressing surface if the printed wiring board is coated with metal foil on one side, but
If both sides are coated with metal foil, this kind of innovation will not be possible and will not solve the problem caused by sagging.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and is designed to eliminate the risk of corrosion such as rust occurring on the exposed surface of the metal plate as a base, and to remove the insulating resin from the metal plate. It is an object of the present invention to provide a highly reliable metal-based printed wiring board that can also prevent the progress of layer peeling.

[Disclosure of the Invention] The metal-based printed wiring board according to the present invention has the following features:
The present invention is characterized in that a metal foil 3 is laminated on the surface of a metal plate 1 via an insulating resin layer 2, and the exposed surface of the metal plate 1 is covered with a resin film 4. explain.

The printed wiring board A is formed as shown in FIGS. 1 and 2 by laminating a metal foil 3 on one or both sides of a metal plate 1 with an insulating resin layer 2 interposed therebetween. Iron plates such as steel plates and stainless steel plates, aluminum plates, brass plates, copper plates, nickel plates, etc. can be used.

Further, as the insulating resin layer 2, a resin-impregnated base material is usually used. Resin-impregnated substrates are made by impregnating and drying thermosetting resins such as epoxy resins, phenolic resins, unsaturated polyester resins, diallyl phthalate resins, polyimide resins, and fluorinated resins into substrates such as glass cloth, synthetic fiber cloth, paper, and nonwoven fabrics. Among them, a prepreg prepared by impregnating glass cloth with an epoxy resin is preferable. Then, this resin-impregnated base material is sandwiched between the metal plate 1 and the metal foil 3 and molded under heat and pressure, thereby laminating the metal foil 3 on the metal plate 1. The metal foil 3 can be made of copper, brass, aluminum, stainless steel, nickel, etc., but if particularly high adhesion is required, it may be adherable to the back side of the metal foil 3. It is best to apply a disinfectant.

In the printed wiring board A formed as described above, the end surface and back surface of the metal plate 1 are exposed in the one shown in FIG. 1, and the end surface of the metal plate 1 is exposed in the one shown in FIG. There is. Therefore, corrosion such as rust is likely to occur on this exposed surface of the metal plate 1. Therefore, in the present invention, resin is applied to the exposed surface of the metal plate 1 to form a resin film 4. As this resin, any resin can be used as long as it does not have any particular problem in adhesion to metals, such as thermosetting, photocuring, room temperature curing, and thermoplastic resins. In order to form the resin film 4 on the exposed surface of the metal plate 1, it is possible to apply till fat in the form of varnish and apply it to the exposed surface of the metal plate 1, or to form a resin film on the exposed surface of the metal plate 1. This can be done by pasting it on the exposed surface of the

Next, the present invention will be specifically explained with reference to Examples.

A steel plate with a thickness of 1.0111111 has a thickness of 0.1 on both the top and bottom sides.
The epoxy resin-impregnated glass cloth with a thickness of 0.035 IOI1 is layered on the outer surface of each layer.
Layer the copper foils of
．． Lamination molding was performed at 170° C. for 160 minutes to obtain a double-sided copper foil-clad reprinted wiring board. Next, an epoxy resin varnish was applied to a local exposed surface of the steel plate of this double-sided copper foil-clad reprinted wiring board and cured, thereby covering the exposed surface of the steel plate with a resin film.

The metal-based printed wiring board obtained as described above is
The specimens were immersed in water at 3° C. for 24 hours, and the water absorption rate and appearance were examined to determine whether rust had formed. For comparison, a similar test was conducted using the printed wiring board obtained in Example 1 without being treated with a resin film (comparative example). The results are shown in the table below.

The results in the table confirm that rust can be prevented by coating the exposed surface of the steel plate with a resin film.

[Effects of the Invention] As described above, in the present invention, the exposed surface of the metal plate is covered with a resin film, so the exposed surface of the metal plate is isolated from oxygen and moisture in the air by the resin film. This prevents rust from forming, and even if part of the insulating resin layer peels off when press-cutting a metal-based printed wiring board, the resin film applied to the metal plate will enter this peeled part and bond. By acting on the adhesive, it is possible to prevent the progress of peeling, and it is possible to prevent the reliability of the printed wiring board from deteriorating.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing an example of a printed wiring board according to the present invention. 1 is a metal plate, 2 is an insulating resin layer, 3 is a metal foil, and 4 is a resin film. Agent Patent Attorney Ashichi Ishida Figure 1

Claims (1)

[Claims] (1) A metal-based printed wiring board characterized in that a metal foil is laminated on the surface of a metal plate via an insulating resin layer, and the exposed surface of the metal plate is covered with a resin film.