JPH02137294A - Manufacture of multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To easily connect and disconnect pin-like conductors with and from conductor layers by inserting and removing the pin-like conductors into and from through holes so as to miniaturize a printed circuit board by forming separated conductor layers on inner walls of the through holes in led-out states. CONSTITUTION:Inner walls 7 of primary through holes are formed by drilling a multilayer circuit board 1 constituted of externally mounted conductors 5, in layer conductors 6, and an insulating base material 2. Then, after performing an activating process on the inner walls 7, primary plated layers 9 are formed on the inner walls 7 by electroless plating, etc. After forming the layers 9, inner walls 8 of secondary through holes are formed by forming prescribed holes in the circuit board 1. Then secondary plated layers 10 are obtained by performing electroplating to the base plate 1. When the electroplating is performed, conductors are precipitated by plating only on the surfaces of the in-layer and outer-layer conductors 6 and 5 exposed on the inner walls 8 of the secondary through holes and the conductors separated from each other rise from the surface of the insulating base material 2 on the inner walls 8. Then unnecessary conductors are removed by etching. Thus a prescribed printed circuit board is obtained. Therefore, the secondary through holes can be connected with and disconnected from through holes 3 through the in-layer conductors 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board having conductor layers separated from each other on the inner wall of a through hole.

[Conventional technology]

Conventionally, a conductor layer on the inner wall of a through hole in a printed wiring board is generally formed uniformly over the entire inner wall surface of the hole by plating or the like. For example, a through hole is formed in a substrate, the inner wall surface of the hole is activated, a very thin conductor layer is formed by electroless plating, and then a conductor layer of a predetermined thickness is formed by electrolytic plating.

[Problem to be solved by the invention]

In the conventional multilayer printed wiring board described above, a conductor layer is uniformly formed on the entire inner wall surface of the through hole, so the method of connecting separated patterns is to use an insulating base material as shown in Fig. 4. In a multilayer substrate 1 formed by forming patterns 4 on 2, through holes 3 are formed at the ends of the patterns 4 separated from each other.
, insert the connecting conductor 13 into this through hole 3,
A method is used to obtain electrical connection between the separated patterns by soldering 14, and in this way, when the patterns 4 of the multilayer board 1 need to be connected later, Since it is necessary to provide two or more through-holes such as the through-holes 3 in advance, the printed wiring board becomes larger and furthermore, the cost increases.

An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board that can be miniaturized and is inexpensive.

[Means to solve the problem]

The method for manufacturing a multilayer printed wiring board of the present invention includes (a) a step of providing a primary through hole at a predetermined position of a multilayer board and forming a conductor layer on the entire inner wall of the member through hole; (I7) forming the multilayer board; further providing a secondary through hole at a predetermined position of the substrate, and depositing a conductor layer on the exposed conductor portion of the inner wall of the secondary through hole and the conductor layer on the inner wall of the member through hole by plating. It is made up of.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(e) are longitudinal cross-sectional views showing the order of steps for explaining the manufacturing method of the first embodiment of the present invention.

In the first embodiment, as shown in FIG. 1(a), first, an exterior conductor 5. A hole is formed in the multilayer substrate 1 composed of the inner layer conductor 6 and the insulating base material 2 to form the inner wall 7 of the -member through hole.

Next, as shown in FIG. 1(b), the inner wall 7 of the member through hole is activated, and electroless plating or electroless plating plus electrolytic plating is performed to obtain a primary plating layer 9. .

Next, as shown in FIG. 1(C), a predetermined through hole is bored to form the inner wall 8 of the secondary through hole.

Next, as shown in FIG. 1(d), electrolytic plating is applied to the multilayer substrate 1 without performing activation treatment on the inner walls 8 of the secondary through holes to obtain a secondary plating layer 10.

At this time, the inner layer conductor 6 exposed on the inner wall 8 of the secondary through hole
A conductor is deposited by plating only on the conductor surface of the outer layer conductor 5, and the conductors separated from each other are formed so as to bulge out from the surface of the insulating base material 2 of the inner wall 8 of the secondary through hole. No plating layer is formed on the insulating base material 2 of the inner wall 8 of the secondary through hole because the activation treatment is not performed.

Next, as shown in FIG. 1(e), unnecessary conductors are removed by etching to obtain a predetermined printed wiring board.

FIG. 2 is a plan view of FIG. 1(e).

A through hole 3 having a land hole is provided in the printed wiring board. The inner layer conductor 6 allows the secondary through hole and the through hole 3 to be connected and separated via the inner layer conductor 6, as indicated by the broken line.

FIGS. 3(a) to 3(c) are a plan view, a plan sectional view of a two-layer inner layer conductor, and a plane sectional view of a three-layer inner layer conductor, respectively, of the second embodiment of the present invention.

In the second embodiment, as shown in FIG. 3(a), the printed wiring board has a through hole 3 formed with a primary plating layer on the inner wall of the member through hole, similar to the first embodiment. The secondary through hole 12 can be connected from three directions via the inner layer conductor 6 from the surrounding primary through holes.

As shown in FIG. 3(b), the secondary plating layer exposed on the inner wall 8 of the secondary through hole connected to the inner layer conductor 6 on the two-layer surface is divided into two parts.

As shown in FIG. 3(c), on the three-layer surface, the secondary plating layer 10 on the inner wall 8 of the secondary through-hole covers the entire circumference of the inner wall 8 of the secondary through-hole, and the inner layer 10 of the inner wall 8 of the secondary through-hole covers the entire circumference of the inner wall 8 of the secondary through-hole. Connected to through hole.

In the second embodiment, by dividing the secondary plating layer 10 of the inner wall 8 of the secondary through hole on the two-layer surface into two parts, it becomes possible to connect and separate three patterns.

〔Effect of the invention〕

As explained above, the present invention provides conductor layers that are separated from each other and are formed on the inner wall of a through hole of a printed wiring board.
It can be easily connected by press-fitting a connecting pin-shaped conductor into the through-hole, and it can be separated by pulling it out, and the number of through-holes can be reduced, which has the effect of downsizing printed wiring boards. .

Further, there is an effect that two or more separate patterns can be connected simultaneously with one through hole.

[Brief explanation of the drawing]

1(a) to 1(e) are vertical sectional views showing the manufacturing method of the first embodiment of the present invention in the order of steps, FIG. 2 is a plan view of FIG. 1(e), and FIG. (a) to (C) are respectively a plan view of the second embodiment of the present invention, a plan cross-sectional view of the inner layer conductor on the two-layer surface, and a plan cross-sectional view of the inner layer conductor on the three-layer surface, and FIG. 4 is the conventional printed wiring. It is a partially notched perspective view of an example of a board. DESCRIPTION OF SYMBOLS 1... Multilayer board, 2... Insulating base material, 3... Through hole, 4... Pattern, 5... Outer layer conductor, 6...
...Inner layer conductor, 7...Inner wall of member through hole, 8...Inner wall of secondary through hole, 9...Primary plating layer, 10...Secondary plating layer, Ro...Land, 12...・Secondary through hole, 13・
...Connection conductor, 14...Soldered.

Claims (1)

[Scope of Claims] A method for manufacturing a multilayer printed wiring board, characterized by having the following steps: (a) providing a primary through hole at a predetermined position of a multilayer board; and forming a conductor layer on the entire inner wall of the primary through hole. (b) Further providing a secondary through hole at a predetermined position of the multilayer substrate, and plating a conductor on the exposed conductor portion of the inner wall of the secondary through hole and the conductor layer on the inner wall of the primary through hole. The process of depositing a layer.