JPS5922397A - 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 an insulating coating 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 efficiency in high-mix, low-volume production.

A typical example of this type of conventional multi-wire wiring board is shown in the first example.
This will be explained with reference to the figures and FIG. As shown in Fig. 1(a), a copper foil layer is formed on an insulating substrate (2) containing a catalyst for non-glare plating, if necessary, so that it can be used as a power supply (1) -1 (ground) layer. 2 is formed on one or both sides, and then, as shown in FIG. 1 (1), after forming an adhesive layer 3 containing a catalyst for no-liquid plating in contact with the rutted substrate 1 and the copper foil layer 2, 81N1 A desired circuit pattern of the insulated wire 4 as the No. 1 circuit is fixed to the adhesive layer 3 using, for example, a numerically controlled automatic wiring device, as shown in FIG.
Furthermore, as shown in FIG. 1(d), in order to protect the circuit pattern formed by the insulated wire 4 fixed to the wiring and to ensure the fixation, a prepreg containing electroless plating #J catalyst is bonded with an irradiation layer. An insulating layer 5 having catalytic properties for electroless plating (hereinafter referred to as catalytic insulating layer) is formed.

Furthermore, after forming a non-conforming mask layer (hereinafter referred to as mask layer) 6 that does not have catalytic properties against electroless plating on the outer surface, insulated wires and copper are placed at desired positions as shown in FIG. 1(e). A through hole 7 is formed across the foil layer 2, and at least a portion of the insulated wire 4 and the copper foil layer 2 are exposed on the inner surface of the through hole 7, and then penetrated by dipping in an electroless plating solution. A metal conductor layer 8 is formed on the wall surface of the hole 7 to form a through pole, and the mask layer 6 is removed as shown in FIG. 1(f).
A multi-wire wiring board as shown in the figure was formed. In the conventional manufacturing process of such a multi-wire wiring board, the mask layer 6 as a plating resist layer was processed on the premise that it would be peeled off after plating was completed.

The mask layer 6 is a polyethylene sheet coated with an adhesive resin layer on one side, and was bonded to the substrate by a method called thermocompression bonding, but it was applied to a high-temperature electroless plating bath at a temperature of 55 to 70 degrees. Due to long-term exposure or mechanical stress, the plating resist layer is sometimes unable to maintain its function as a stable plating resist layer, resulting in partial peeling or damage of the mask, resulting in unplated areas being damaged. , plating precipitation may occur.

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 coated with an electroless-plated through-hole conductive layer on the wall of a through-hole drilled on the substrate. In the manufacturing method of a multi-wire wiring board formed by forming and connecting insulating coated wires, a substrate on which an insulating resin layer having catalytic properties for electroless plating has been laminated on a pattern after wiring insulation coated wires. The production of a multi-wire wiring board is characterized in that it includes a step of applying an insulating ink that does not have catalytic properties to electroless plating to areas other than the portions corresponding to the through-hole lands on the insulating resin layer. method is obtained.

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

FIG. 3 is a sectional view showing an embodiment of the present invention.

FIG. 3(a) shows a wiring board in an intermediate step manufactured in the same manner as in FIGS. 1(a) to 1(C) of the conventional example described above. A desired number of sheets of prepreg having catalytic properties for non-removal plating are stacked on both sides of the wiring board, and the upper and lower surfaces of the structure are covered with flat plates (not shown) having sufficient rigidity and made of stainless steel, for example. The catalytic insulating layer 5 is formed by heating and pressurizing the flat plate structure. After the formation of this catalytic insulating layer 5, the catalytic insulating layer 5
A thermosetting ink that does not have catalytic properties is applied to the outside of the electroless plating layer, and on the catalytic insulating layer 5, through-hole lands are formed in subsequent steps. For the part, screen printing is performed using printing and printing patterns that have relief parts.

After applying the ink by screen printing, it is cured by means such as heating.

By the above method, as shown in Fig. 3(b), an insulating layer (hereinafter non-catalytic insulating
9).

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,
At least a part of the insulated wire 4 and the copper foil layer 2 are exposed on the inner wall surface of the through hole 7, and then immersed in an electroless plating solution to coat the inner wall surface of the through hole 7. A metal conductor layer 8 was formed as follows.

Since the non-catalytic insulating layer 9 is formed to be stable and strong like the inner and outer layers of the substrate, there is no plating precipitation on areas that cannot be plated due to damage etc. that was observed when using the conventional mask layer 6. Even after being used as a plating resist layer, there is no problem in forming a part of the product to protect the base material, and the residual material is highly effective as a protector for the base material.

As described above, the following effects have been achieved by the present invention.

(1) Since it is possible to maintain the adhesion of the conventional plating resist (11&) during plating, the occurrence of bridging due to the plating conductor and the occurrence of insulation debris etc. can be reduced.

(11) Since there is no need 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 no damage to the plate surface, which often occurs during removal.

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

[Brief explanation of the drawing]

1(a) to 1(f) are cross-sectional views of the manufacturing process of a conventional multi-wire wiring board, and FIG. 2 is a perspective view of FIG. 1. Figure 3 (a
) to (d) are cross-sectional views of the manufacturing process of the multi-wire wiring board of the present invention. ■...Insulating substrate, 2...Inner steel foil layer,
3... Adhesive layer, 4... Insulating coated wire, 5... Catalytic insulating layer, 6... Mask layer, 7... Through hole, 8... Metal conductor layer, 9... Non-catalytic insulating layer. Figure 1 ゛” / Figure #2

Claims (1)

[Claims] A circuit pattern is formed by wiring an insulated wire on an insulating substrate, and the terminal end of the wire is connected by forming an electroless-plated through-hole conductive layer on the wall of a through-hole provided on the substrate. In the method for manufacturing a Yaruchi wire wiring board, the insulating layer is applied to a substrate on which an insulating resin layer having catalytic properties for electroless plating has been laminated on the pattern after wiring the insulating coated wire. 1. 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 to areas other than those corresponding to through-hole lands on a polyurethane resin layer.