JPS5880896A - Method of producing through hole lint 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 The present invention provides a method for manufacturing a through-hole printed wiring board in which a desired wiring pattern is provided using steel foil on both sides of an insulating substrate such as polyimide film, glass epoxy resin, etc., and the wiring patterns are electrically connected to each other. Regarding.

Conventionally, the method of making this type of through-hole printed S board has been to use a method that mocks through-hole plating.In other words, steel is coated on both sides of an insulating board such as polyimide film or glass epoxy. Laminate the foil L1. Next, a through hole is formed at a predetermined location, and then electroless steel plating and electrolytic steel plating are applied to plate the inside of the hole with steel to make the steel foils on both sides electrically conductive. Thereafter, a resist such as 7-otoresist is placed on the substrate, and a desired wiring pattern is exposed and etched to obtain a wiring pattern. Since the holes are intentionally formed, the uniform wiring pattern becomes electrically conductive due to the copper deposited within the through holes.

However, the above-mentioned conventional one-manufacturing method has the disadvantage of high cost due to electroless steel plating and electrolytic steel plating, and also because cocoons of electrolytic steel plating adhere to the steel foil. One drawback is that it becomes thicker, making it difficult to form lines with narrow line spacing.

The present company has developed a 1L through-hole printed wiring board that ensures continuity between the wiring patterns provided on both sides of the insulating board, and also simplifies the front process and reduces costs.
This paper aims to provide a method for manufacturing Ii. The means for achieving this objective is to laminate steel foil on one side of an insulating substrate, provide a hole with a diameter of one radius thicker than the thickness of the insulating substrate, and laminate steel foil on the other side. A wiring pattern having a steel foil portion covering the hole is formed, and then a pressing mold is inserted from above the steel foil portion on the other side to bend the steel foil portion into the hole and the steel foil portion protrudes to one side. The tip of the foil is brought into contact with the foil on one side.

Embodiments of the present invention will be described in detail below with reference to process diagrams shown in FIGS. 1 to 6.

Reference numeral 1 in the figure represents a film-like insulating substrate made of polyimide. A steel foil 2 is laminated on the entire surface of one side of this insulating substrate l as shown in Fig. 1! (see #A in FIG. 2), and a hole 3 having a radius larger than the plate of the insulating substrate 1 is passed through (see #A in FIG. 2). Hole 3t
- Laminate steel foil 4 on the entire other side of the opened insulating substrate l (see 18314 #IN).

Next, steel foil laminated on both sides of Zettai #4 board l?・
4 by a known method to obtain the desired wiring pattern (see Figure 4). To obtain the desired wiring pattern by etching, for example, after coating the copper foil with 7 photoresist, the desired wiring pattern is obtained. There is a method of exposing the wiring pattern, developing it, and then etching it. The steel foil 4 on the other side connects the hole 3 to the steel foil part 4.
′ is formed so as to cover it. Therefore, the steel foil W64 on the other side
'From above, press IJ1s, a sharp round bar tool, to press the steel foil part 4/
While breaking the center part, push it into the hole 3. The radius of the stamp S is smaller than the radius of the hole 3 by the thickness of the steel foil 4. This is because when the stamp S is pushed into the hole 3, the broken steel foil portion 4' is pressed against the inner wall of the hole 3. This is to bend it into the hole 3 while pressing it down (see Fig. 5). When the steel foil 5IS4' having a radius larger than the plate thickness of the insulating substrate l is bent by the stamping die i, its tip #i protrudes toward the wire foil 2 side, and its tip is further bent. The tip of the steel foil part 4' that has been brought into contact with the steel foil part 3 is bent and brought into contact with the steel foil part 3' to make the steel foils 3 and 4 electrically conductive (see Figure 6). Connect to @J as shown in Figure 7,
The tip of the steel foil portion 1' may be connected to the tin foil layer with solder 6, and furthermore, a conductive paste may be used in place of the solder 6.

In the above embodiment, a flexible film made of polyimide is used as the insulating substrate l, but a soft or hard insulating substrate made of glass epoxy resin may also be used.

f&, in the above embodiment, when bending the steel foil Wh4' into the hole 3, the steel foil g4'
Although the steel foil @a/ was bent without breaking, it goes without saying that the steel foil @a/ may be bent separately using a sharp die for breaking and a bar-shaped die for folding 1 ml. Furthermore, the center part of the steel foil part is punched out using a small-diameter breaking die, and the center part is punched out by bending the am part to punch out the center part using a small-diameter breaking die. *m
This is to ensure that the bent tip will stick out from the wiring pattern with the land note when it comes into contact with the steel foil. It is bent by inserting a small, single-layer stamp into the hole, and its tip is further bent to contact the steel foil on the opposite side.◎ As explained above, the present invention covers the hole drilled in the insulating substrate with the steel foil. While bending the foil part into the hole, Il! The tip of the steel foil that protrudes from the side is further folded so that it comes into direct contact with the steel foil on the other side, ensuring continuity and making sure that the contact between the steel foils is on the front side of the insulating bottle plate instead of inside the hole. - The contact state can be confirmed visually and a more reliable conductive state can be maintained.

In addition, since there is no need to perform electroless steel plating or electrolytic steel plating, the process can be simplified and the equipment can be reduced, and the steel foil layer does not have to be thick and the wire spacing is narrow, making it possible to This has the advantage that a 41# bright wiring pattern can be obtained and costs can be reduced.

[Brief explanation of drawings]

Figures 1 to 6 are diagrams showing each process of an embodiment of the present invention, Figure 1 is a cross-sectional view of the process in which steel foil is laminated on one side of the insulating board, and Figure 21iW is a cross-sectional view of the process in which a hole is drilled. figure,
Figure 3 is a cross-sectional view of the next process in which steel foil is laminated on the other side of the insulating substrate, Figure 4 is a cross-sectional view of the nine steps in which the desired pattern is obtained after etching, and ll5m is a cross-sectional view of the next process in which the steel foil portion is bent with a pressing die. , FIG. 6 is a process drawing in which the tip of the steel foil portion is convergent to the steel foil on one side. FIG. 7 is a cross-sectional view of the process in which the contact portion of the steel foil portion is soldered. 1... Insulating substrate, 2... 4... Group steel foil, 3...
...hole, 4'...steel foil part, S...
Press type. Patent Applicant Shindo Electronics Industry Co., Ltd. Agent Patent Attorney Shun Nakao 1 Figure 2 Figure 3 Figure 4 Figure 5 F 〒 Figure 6 to Figure 7

Claims (1)

[Claims] Laminate steel foil on one side of the insulating substrate to provide a hole with a radius larger than the thickness of the insulating board, and laminate steel foil on the other side to cover the hole and form a wiring pattern having a steel foil portion. Next, press a mold from above the other steel foil part to bend the steel foil part into the hole, protrude to the - side, and bend the tip of the steel foil part to the one side of the steel foil. A method for producing a through-hole printed wiring board, which is characterized by making steel foils on both sides electrically conductive by bringing them into contact with each other.