JPS6398178A - Metal base printed wiring board - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a metal-based printed wiring board that has been subjected to a patterning process.

[Background technology 1] Metal-based printed wiring boards are available in the United States, which are based on metal plates such as silicon steel plates and have excellent heat resistance, resistance to damage, shielding effects, mechanical strength, and heat dissipation properties. However, when such a printed wiring board is bent and drawn,
Microcracks occurred in the anti-rust layer made of a non-isoga layer pre-formed on the silicon steel plate at the bent portions, and rust increased due to humidity, resulting in poor rust resistance reliability.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to ensure rust prevention of bent portions during bending and drawing in metal-based printed wiring boards. .

[Disclosure of the Invention] The metal-based printed wiring board of the present invention is a metal-based printed wiring board in which a conductor pattern 3 is formed on a metal plate 1 via an insulating layer 2, and *1 is formed on the exposed surface 1a of the mounting board 1. It is characterized by forming a secondary rust prevention M4 and also forming a secondary & fourth layer 6 on the exposed surface 5a side of the bent portion 5 of the metal plate 1 which is bent during the bending process. With this configuration, the above objectives were achieved. That is, even if cracks occur in the primary rust prevention layer 4 of the bent portion 5 of the metal plate 1 due to bending and drawing, the reflux is covered with the secondary rust prevention N6 to prevent moisture from entering the metal plate 1. It is possible to prevent rust and ensure rust prevention.

Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings. The metal plate 1 used in the present invention may be made of iron, aluminum, copper, nickel, or an alloy thereof. This metal plate 1 is provided with a second primary antirust layer 4 on the exposed surface 1al.

On the opposite side of the metal plate 1 to the exposed surface 1a, a continuous layer 2 such as prepreg, for example, aluminum? L
mW, gold In like stainless steel foil, nickel foil, iron foil
IN is pasted, and a conductive pattern 3 is formed by a conventional method to form a metal base printed wiring board A. In this metal-based printed wiring board A, in practical use, the recess 7 is formed by bending and drawing. A secondary rust preventive layer N6 is formed on the exposed surface 5a side of the bent portion 5 of the metal plate 1 that is bent during the bending and drawing process. The two-layer TII layer 6 is formed of an organic layer such as epoxy resin or an inorganic layer such as water glass. This secondary anti-corrosion layer 6 may be formed either before or after bending and drawing when formed from an organic layer, and preferably after bending and drawing when formed from an inorganic layer.

The metal-based printed wiring board A formed in this manner and subjected to bending and drawing processing was placed under conditions of a temperature of 60 cm and a humidity of 9595 cm, and the rust prevention effect of the bent portion 5 was measured.
Secondary rust prevention) In the case where tI6 was formed of epoxy resin, no rust occurred even after 500 hours. Also, 2
50% even if Rustproof No. 6 is made of water glass.
No rust occurred at 0hrf&.

On the other hand, in the case where only the primary rust prevention/C4 was formed and the secondary rust prevention/C46 was not formed, a large amount of red rust occurred after 481+r. Note that the radius of curvature of the bend g5 was 3+aa+.

[Effects of the Invention] The second aspect of the present invention is that it is based on a metal plate.
Not only does it have excellent heat resistance, flame retardancy, shielding effect, mechanical strength, and heat dissipation, but even though it is based on a metal plate, it forms a primary rust prevention layer on the exposed surface of the metal plate. At the same time, a secondary rust prevention layer is formed on the exposed surface of the bent portion of the metal plate that is bent during the bending and drawing process, so cracks will occur in the primary rust preventive layer at the bent portion of the metal plate during the bending and drawing process. Even so, by covering the cracks with the secondary rust-preventing layer, it is possible to prevent moisture from entering the metal plate as a whole, thereby ensuring rust-proofing properties, and significantly improving rust-resistant reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, in which A is a metal base printed wiring board, 1 is a metal plate, 1a is an exposed surface, 2 is an insulating layer, 3 is a conductive pattern, and 4 is a primary Rust prevention layer, 5
5a is the exposed surface, and 6 is the secondary rust prevention Iη. Agent Patent Attorney Ishi 1) Ai Figure 7 1

Claims (1)

[Claims] (1) A metal-based printed wiring board in which a conductor pattern is formed on a metal plate through an insulating layer, and a primary rust prevention layer is formed on the exposed surface of the metal plate, and the metal plate is bent during bending and drawing. A metal-based printed wiring board characterized by forming a secondary anti-rust layer on the exposed surface side of the bent portion.