JPS5922396A - Method of producing multiwire 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 relates to a method for manufacturing a multi-wire wiring board, and particularly to a method for forming a plating resist layer used during a through-hole plating process.

In recent years, as mounting components such as ICs have become smaller and more highly integrated, there has been a growing demand for higher precision and higher density wiring patterns for printed wiring boards. Furthermore, as needs become more diversified, there is a growing tendency to produce a greater variety of products in smaller quantities.

A multi-wire wiring board forms a signal circuit by cross-wiring insulated wires on an insulating adhesive layer on a wiring board.

Therefore, not only does artwork such as original drawings and photographs that are necessary in the production of printed wiring boards become unnecessary, but it also facilitates high-density mounting, contributing to improved cost performance in high-mix, low-volume production.

A typical example of this stock's conventional multi-wire wiring board is shown below.
This will be explained with reference to the figures and FIG. As shown in Fig. 1(a), on an insulating substrate l containing a catalyst for electroless plating, paulownia foil j@2, which has been made into a batten, is coated on one side or so that it can be used as a power supply layer or a ground layer, if necessary. Then, as shown in Fig. 1 ([)], after forming an adhesive layer 3 containing a catalyst for non-plating plating in contact with the insulating J plate 1 and @ foil layer 2, as shown in Fig. 1 A desired circuit pattern of the insulating coated wire 4 as a signal circuit as shown in (C) is created using, for example, a numerical system.
The wires are fixed to the adhesive layer 3 using a type 1 automatic wiring device, and then the insulated wire 4 is fixed to the adhesive layer 3 as shown in FIG. 1(d).
In order to protect the circuit pattern and ensure adhesion, a prepreg containing a catalyst for electroless plating is laminated to form an insulating layer (hereinafter referred to as a catalytic insulating layer) that has catalytic properties against deplating. 5).

Furthermore, after forming a non-conforming mask layer (hereinafter referred to as "mask") 6 which does not have catalytic properties against electroless plating on the outer surface ++i, insulated wires and copper are placed at desired positions as shown in FIG. 1(e). A through hole JL7 is bored across the foil layer 2,
At least a portion of the insulating coated wire 4 and @ foil layer 2 are exposed on the inner surface of the through hole 7, and then a metal conductor layer 8 is formed on the wall surface of the through hole 7 by immersing it in an electroless plating solution to form a through hole, As shown in FIG. 1(f), the mask layer 6 is removed to form a multi-wire wiring board as shown in FIG.
It was something that

In the conventional manufacturing process of such a multi-wire wiring board, the mask layer 6 as a plating resist layer was processed 5 on the assumption that it would be peeled off after plating was completed.

The mask layer 6 is made by coating one side of a polyethylene sheet with an adhesive resin layer, and pasting to the substrate was done by thermocompression bonding, but electroless plating at a high temperature of 55 to 70°C was used. In general, due to long-term exposure or mechanical stress, it is sometimes impossible to maintain the function of a stable plating resist layer, and parts of the mask that cannot be plated may be peeled off or damaged. In some cases, plating precipitation occurred.

The object of the present invention is to provide a method for manufacturing a multi-wire wiring board that overcomes these conventional drawbacks.

According to the present invention, a circuit pattern is formed by wiring and fixing an insulating coated wire on an insulating substrate, and the terminal end of the wire is electrolessly plated on the hole wall of a through hole drilled on the substrate. In the method for manufacturing a multi-wire wiring board formed by forming and connecting layers, the formation of an insulating, fat-resistant layer having catalytic properties against plating is completed on the pattern after wiring the insulating coated wires. Insulating P, which does not have catalytic properties against electroless plating, is applied to the entire area on the insulating resin layer for the substrate.
A method for manufacturing a multi-wire wiring board is obtained, which includes the step of applying L ink and pasting.

The present invention will be explained below with reference to FIG.

FIG. 3 is a diagram showing one embodiment of the present invention.

FIG. 3(a) shows the state of the wiring board in the intermediate process manufactured in the same manner as in FIG. 1(C) of the conventional example described above. A desired number of sheets of prepreg having catalytic properties against non-1F deplating are stacked on the front and back screens of this wiring board, and the upper and lower surfaces of the structure are made of planar plates (not shown) having sufficient rigidity and made of stainless steel, for example. The planar plate structure is then held and heated and pressurized]7 to form a catalytic insulating layer 5. After the formation of this M:It medium embellishment layer 5, a thermosetting ink that does not have catalytic properties for electroless plating is applied to the outside of the catalytic insulation 1-5, and this is pasted by heating etc. Harden depending on the method.

By the above method, as shown in FIG. 3(b), an insulating layer 9 having no catalytic properties for electroless plating (hereinafter referred to as a non-catalytic insulating layer) 9 is formed.

Next, as shown in FIG. 3(C), a through hole 7 is bored at a desired position so as to cross the insulated wire 4 and the copper foil layer 2,
After exposing at least a part of the insulation coated wires 4 and f(1+I) to the inner wall surface of the shell hole 7, a third layer is formed on the inner wall surface of the through hole 7 by immersing it in an electroless plating solution. A metal conductor layer 8 was formed as shown in Figure (d).

The non-catalytic insulating layer 91i is stable like the inner and outer layers of the substrate, and
Because it is firmly formed, there is no plating precipitation on areas that cannot be plated due to damage etc. that was seen when using the conventional mask layer 6, so even after it is used as a plating resist layer, it can be used to protect the base material. Not only does it pose no problem even if it forms part of a product, but the residual material also has a great effect as a protector for the substrate.

As described above, the following effects were obtained by the present invention.

(1) During plating, the density Ii is higher than that of conventional plating resist layer.
Because it is possible to maintain the properties of the conductor, it has been possible to reduce the occurrence of bridging due to plated conductors and poor insulation.

(g) Since it is not necessary to remove the plating resist layer as in the conventional method, there are not only advantages of reduced man-hours and lead time, but also the damage to the substrate surface that frequently occurs during removal can be completely eliminated.

(iiQ The mechanical and environmental stability of the board after component mounting is improved.

[Brief explanation of drawings]

1(a) to 1(f) are cross-sectional views of the manufacturing process of the conventional multi-wire arrangement t, FIG. 2 is a perspective view of FIG. 1, and FIG.
11~<d) of the multi-wire wiring board of the present invention:! Cross-sectional mj diagram of A construction factory. l...Insulated substrate, 2...(Inner layer) copper foil, 3...Adhesive layer, 4...Insulated wire, 5... ...Catalytic insulating layer, 6...
Mask layer, 7... Through hole, 8... Metal conductor layer, 9... Non-catalytic insulating layer. ? Destruction? figure

Claims (1)

[Claims] At the same time, wire an insulated coated wire on the substrate to form an 11-way button, and form an electroless-plated through-hole conductive layer on the hole wall of the through-hole provided on the substrate at the terminal end of the wire. In the method for manufacturing a multi-wire wiring board connected by the following process, the above-mentioned method is applied to a substrate on which an insulating resin layer having catalytic properties for electroless plating has been formed on the pattern after wiring the insulating coated wires. A method for manufacturing a multi-wire wiring board, comprising the step of applying an insulating ink that does not have catalytic properties to electroless plating over the entire area on an insulating resin layer.