JPS5835998A - Method of producing multilayer 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 combines rigid (rigid) circuit parts and flexible (
The present invention relates to a method for manufacturing a multilayer wiring board having a flexible (flexible) circuit portion.

When electrically connecting a rigid wiring board to another wiring board, it is preferable that the connection end is a flexible part. If the circuit part (2) has a laminated structure, the connection end part has flexibility, so interconnection with other wiring boards (4) becomes easy and reliable, and both bases 11 (1) And (4) also has the advantage of increasing the degree of freedom in the installation location.@In addition, (5)
and (6) show the circuit turns of each board, and (7) shows the conductive material such as solder filled through the opening.As for the conventional manufacturing method of this type of multilayer circuit board, for example, Figure 2 shows Hard Bakelite substrate (8) as shown in A and BK
- A rigid circuit part shaft formed with a first layer circuit (9) formed on the main surface of the flexible circuit part a3 formed with a second layer circuit αδ made of copper foil on a polyimide film αυ are separated, respectively. The connection part (opening part) (14) of the flexible circuit part 0 is drilled, and adhesive a is applied to the back side.
After applying S and tightening it to the rigid circuit part, drill the connection part (14+ filled with solder AE and the through hole Q that passes through the connection part of the required circuit) and connect the required electrical parts. Or, as shown in @3 Figures M and B, a flexible wiring board (2) is provided in which a double-sided circuit board and Oa are formed using through-hole plating 0 on a polyimide P film (r11). Hard Bakelite substrate (8) via adhesive α9 K! I! Align D, and then insert the P rill into the through hole A through which the connection part of the required circuit passes. ) is connected to the required electrical component alt. However, in the former case, the accuracy of the tensioning between the rigid circuit part α and the flexible circuit part αj is poor (the flexible circuit is connected before joining). The flexible circuit part (I3 circuit formation has no rigidity and is difficult to handle, and the solder connection between the 1st layer circuit (9) and the 2nd layer circuit (2) is 1. It is not suitable for mass production because each hole is filled with solder by hand, it is difficult to drill the holes and it is difficult to connect circuits together, and the hole diameter cannot be made small because the hole is drilled using a P drill, which occupies circuit 0. There are problems such as the area becomes large, hindering high density, and it is not possible to implement a continuous production process.

In addition, in the latter case, the manufacturing process of the flexible wiring board is complicated and requires wastewater treatment equipment, which makes it difficult to handle. Since the holes are drilled in the wiring board using a P drill, there are limits to the hole diameter, which makes it difficult to form high-density circuits.1) It is not possible to implement a continuous production process, which is a problem.

The present invention solves the above-mentioned problems and provides a method for manufacturing a multilayer wiring board that is suitable for mass production and enables high-density circuit formation.

Hereinafter, a method for manufacturing a multilayer wiring board according to the present invention will be explained using FIG. 4A-1.

First, as shown in FIG. 4A, the present invention uses a so-called steel-clad multi-laminated board made of a rigid insulating substrate 0υ made of paper phenol, paper epoxy, or glass epoxy, covered with copper foil (2). This copper foil is selectively etched to form the first layer of interconnection turns (2), and the first layer having the interconnection turns is then separated from the first layer. Separation means (9) are provided which can be separated by mechanical force in relation to the second part (to). This separation means (
In the case of b), the illustrated example has so-called perforations (to) with predetermined holes made at equal intervals, but it is also possible to provide V-wave grooves along the separation line on the back side. Next, as shown in FIG. 4B, a release layer is formed on the flap 20 portion of the substrate 0υ by release printing or taping. For release printing, for example, epoxy resin containing 10% or more of silicone resin liquid, silicone ink based on phenol resin paint, or Teflon powder (particle size 5~
Ink containing epoxy or phenol resin containing 50μ) can be used. In addition, as the taping, a silicone film (silicon resin liquid) or a Teflon film (Teflon tape) coated with an acrylic emulsion adhesive can be used.Next, as shown in Figure 4C, on the base 1liCA1) Almost the entire surface of the first layer wiring pattern, that is, the connection part (a) with the first layer wiring pattern to be formed later, the electrical component connection part (not shown), and the connection part with other wiring boards. A flexible insulating resin layer (43 is formed by printing on the entire surface except for the part corresponding to 4υ)・This insulating resin layer (a is, for example, epoxy polyamide P%
After laminating a conductive foil layer, such as steel foil, on the entire surface of the insulating resin layer (6), which can be made of poxy acrylate, urethane acrylate, or a blended resin, as shown in FIG.
As shown, the copper foil is selectively etched to form an opening (2) that reaches the connection part (G) of the second layer wiring pattern (B) and the first layer wiring pattern (B).
In the opening (c), the adhesive ω from when the copper foil was pasted remains, so the adhesive in that area was further removed with an organic solvent, and the first layer wiring pattern (b) was removed. At the same time as this second layer wiring/turn αj is formed, an opening 6@ can be formed at a position corresponding to a connection portion with another wiring board.

Next, as shown in Fig. 4 E, fill the opening of the second layer wiring (2nd turn) with a conductive material (c) and connect the upper and lower wiring turns (9th turn). . After that, the substrate eη is separated along the perforation (to) by mechanical means and the second part (to) is removed. This second part (to) is separated from the insulating resin layer by the mold release layer (to). (6) Also released from the mold. As the conductive material (c), a conductive material made by metal spraying with a low melting point metal such as gallium alloy, solder dip, silver paste), cu, Zn, Sn, etc. can be used. Especially. In the case of a gallium alloy, gallium itself is liquid at room temperature of 30°C or below, a metal that is eutectic with gallium, and a metal powder (single metal powder or alloy powder) that can be alloyed with gallium and raise its melting point. The conductive material of this gallium alloy has the property of initially forming a paste form at the working temperature, and then alloying and solidifying over time. When using this gallium alloy, it is necessary to It avoids the problem of silver migrating that occurs with paint, and it also has the same electrical conductivity as Cu plating, making it possible to form high-quality circuits.

As a method for separating the second portion (to) of the substrate r31), for example, as shown in FIG.
C) After filling the laminate υ with rollers (to) and (b)
Insert the presser (c) between the two and push the second part (to) downward.
If you push it up at the perforation, it will be easily separated.

By doing this, as shown in FIG. 4E, on the rigid circuit part □□□ having the first layer wiring pattern,
A multi-layered layer consisting of nine flexible circuit parts (6) and a second layer wiring (3) with a second layer wiring so that the connection end (67) with another wiring board protrudes from its edge. Obtaining the wiring board (to) - When connecting this multilayer wiring board 69 to another wiring board, connect the connecting end 67 of the flexible circuit part (to) to the other wiring board (as shown in FIG. 1 above).
4) Connect the second layer wiring pattern (to) and the opening 6D on the connection end of the other wiring board (4) (see FIG. 1).

are stacked so as to match the required number of turns of the O circuit, and the opening fJa is filled with a conductive material (c).

According to the manufacturing method of the present invention described above, the rigid insulating substrate c11
), a first layer wiring pattern (b) is formed on the insulating substrate 61, and a flexible insulating resin layer is formed on the second layer wiring pattern (b). By separating and removing the second portion corresponding to the connection portion with another wiring board, this type of multilayer wiring board can be manufactured with high productivity while forming high-density circuits. In particular, the openings (materials) for connection between the two wiring patterns (b) and (43) are formed by chemical etching without using the conventional P rilling process, so the pores are fine in diameter. The area occupied by the wiring/turns 04) (to) including the connection portion can be small, and high density can be achieved. Furthermore, since the openings can be formed in the rigid substrate state, handling during the manufacturing process is facilitated.

In addition, since the distance between both wiring patterns (b) and (to) is small due to the insulating resin layer (6), when filling a conductive material (c) such as a gallium alloy, it can be easily filled by printing means, so that continuous school children can use it. This makes it possible to connect to other wiring boards, since an opening 61) can be provided in advance at the connection end.
You can easily connect using

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the connection state of different wiring boards for explaining the present invention; FIG.
4 is a process diagram showing an example of a conventional multilayer wiring board manufacturing method, respectively.
Figures A-B are process diagrams showing the manufacturing method of the present invention, Figures 5 and B are cross-sectional views showing an example of the separation process of the present invention, 00J is a rigid insulating substrate, (B) is the first layer wiring pattern, (to) is the first part, (to) is the second part, (to) is the perforation, (to) is the release layer, (c) is the first layer wiring pattern, (goods) is the opening. Yes, Figure 2

Claims (1)

[Claims] The first part of the board is made up of a part of the board 1 with the required wiring turn, and a second part connected to the first part but separated by mechanical force. a step of forming a release layer on the first portion and the second portion, a step of printing an insulating resin layer except for at least the upper and lower connecting portions of the first portion and the second portion and the electrical component connecting portion; A step of depositing a conductive foil layer on the resin layer; and a step of applying a conductive foil layer to at least the first portion of the conductive foil layer. A method for manufacturing a multilayer wiring board, comprising a step of forming and connecting an opening up to 1/2 inch, and a step of mechanically separating the front I'12 part from the first part.