JPS62117392A - Formation of holes of printed circuit 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 [Technical Field] The present invention relates to a method for forming holes, such as mounting holes, exposed on the surface of a printed wiring board using metal as a substrate.

[Background technology]

As seen in FIG. 3 (al) and FIG. 4 (al), printed wiring boards in which electrical circuits 12 are formed on a metal substrate 10 via an insulating layer 11 are already well known.

By the way, as shown in FIG. 3(b) and FIG. 4(bl), a hole 13 exposed on the surface such as a mounting hole is formed in this.This hole 13 can be used alone or after the electric circuit is formed. ,
At the same time as the external form jJIl King, jJIl ] IT was being done. However, with this forming method, metal was exposed on the hole wall surface, so rust was generated from the hole wall surface. In addition, the stress during hole drilling caused adhesion breakdown between the insulating layer and the metal substrate, reducing the reliability of the printed wiring board in terms of electrolytic corrosion and moisture resistance after the hole was formed and exposed on the surface. .

[Purpose of the invention]

In view of the above circumstances, the present invention eliminates the generation of rust from the hole wall surface of the printed wiring board, and reduces reliability such as electrolytic corrosion and moisture resistance of the printed wiring board after forming the hole exposed on the surface. It is an object of the present invention to provide a method for forming holes in a printed wiring board without causing problems.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a method for forming holes exposed on the surface of a printed wiring board using a metal as a substrate.
A hole larger than the hole is provided in the metal substrate at the position where the hole is to be provided, and this large hole is filled with an insulating material, so that a layer of the insulating material remains on the wall surface of the large hole. The gist of the present invention is a method for forming holes in a printed wiring board, characterized in that processing is performed to form holes exposed on the surface.

An embodiment of this will be explained in detail below based on the accompanying drawings.

A printed wiring board with holes exposed on the surface as shown in FIG. 1 fb+ is formed in advance. That is, as shown in the figure, in this printed wiring board 9a, a metal foil 6 is laminated on a metal substrate 2 via an insulating layer 5 (made of resin in this embodiment).

In the metal substrate 2, each hole 3...larger hole 1... is formed at the position where the hole 3... exposed on the surface is provided, and an insulating material is insulated in all of these large holes 1... (in this example, resin) 4 is filled. To obtain this printed wiring board 9a, as shown in FIG.
...Metal substrate 24 with larger hole 1... formed
゛Preparation 1.7: After filling these large holes 1 with insulating material 4, an insulating layer 5Jl and metal foil (
j are stacked one after the other. In this embodiment, the same resin is used for filling the large holes 1 and the resin for the insulating layer 5. To obtain the printed wiring board,
Following the method described above, a metal substrate as shown in FIG. Alternatively, a thick hole in the metal substrate may be filled with the metal substrate. After forming the printed wiring board 9a as described above,
As shown in FIG.
At the same time, the walls 6. of the large holes l... are formed. - Processing is performed to open holes 3 exposed on the surface so that the layer of insulator 4 remains, and holes 3 exposed on the surface are formed in the printed wiring board. Holes that are exposed on the surface should be drilled with an L shape by drilling or punching. The shape of the hole exposed on the surface may be a non-through hole like the leftmost hole shown in Figure 1 (C1) or a through hole like the other holes.Formation of an electric circuit. Either of the process or the process for making a hole exposed on the surface may be performed first, or they may be performed simultaneously.

In the printed wiring board 9a' in which the holes exposed to the surface are formed in this way, since an insulating layer remains on the wall surface of the large hole 1, the wall surface of the hole 3 exposed to the surface remains. No metal is exposed to the holes 3, and rust does not form on the walls of these holes 3. In addition, these holes 3...larger holes 1... are provided at the positions where the holes 3... exposed on the surface of the metal substrate are provided, and these large holes l...
・Since the insulator is filled with an insulating material and processing is performed to make a hole exposed on the surface, the adhesion between the metal substrate 2 and the insulating layer 5 is not destroyed, and the hole exposed on the surface can be formed. The method of forming holes in the printed wiring board 9a, which has metal foil laminated on one side with an insulating layer interposed therebetween, is recommended as long as it does not later reduce the reliability of the printed wiring board in terms of electrolytic corrosion and moisture resistance. Although examples have been shown, Fig. 2 (al, fb), (cl
shows an example of a method for forming holes in a printed wiring board 9b having metal foil laminated on both sides with insulating layers interposed therebetween. In such a printed wiring board 9b, processing is performed to make holes exposed on the surface in the same manner as the printed wiring board 9a shown in the above embodiment, so that holes exposed on the surface are formed. The printed wiring board 9b' is the printed wiring board 9a of the above embodiment.
The same effect as ′ can be obtained. In the figure, 8 indicates a metal plating layer applied to the wall of the hole exposed to the surface in order to connect the electric circuit formed on both sides. This metal plating layer is formed after forming holes exposed on the surface.

The method for forming a hole in a printed wiring board according to the present invention is not limited to the above-mentioned embodiments.The degree of filling of the insulator may be tightly packed or may be such that the wall surface of the large hole is covered with the insulator. .

〔Effect of the invention〕

As described above, the method for forming holes in a printed wiring board according to the present invention includes providing a hole larger than the hole exposed on the surface of the metal substrate at a position where the hole is exposed on the surface of the metal substrate.
This large hole is filled with insulating material and processed to make the hole exposed on the surface, so that the adhesion between the metal plate and the insulating layer is not destroyed. After forming the holes exposed on the surface, reliability such as electrolytic corrosion and moisture resistance of the printed wiring board will not be reduced.

Since the insulating layer remains on the wall of the hole exposed to the surface and no metal is exposed, rust does not form on the wall of the hole.

[Brief explanation of drawings]

Figure 1 (fat, bl, fcl) is an explanatory diagram showing one embodiment of the method for forming holes in a printed wiring board according to the present invention, and Figure 2 (at, fb), (c) is an explanatory diagram showing another embodiment, respectively. Diagram explaining the hail, Figure 3 (al, (b)
4 (al) and 4 (b) are explanatory diagrams of conventional methods of forming holes in printed wiring boards, respectively. 1...Large hole 2...Metal plate 3...Exposed on the surface Hole 4...Insulator

Claims (1)

[Claims] (1) When forming a hole exposed on the surface of a printed wiring board using a metal substrate, a hole larger than the hole is provided at the position of the metal substrate where the hole is to be provided, and this large hole is filled with an insulator. A method for forming a hole in a printed wiring board, characterized in that the large hole is processed so that a layer of the insulating material remains on the wall surface of the large hole and the hole is exposed on the surface. .