JPS6332991A - Manufacture of printed wiring board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a printed wiring board, and particularly to a method for manufacturing a through-hole printed wiring board having through holes.

[Prior Art] A conventional method for manufacturing a printed wiring board having through holes is as follows. That is, first, as shown in Figure 2 (a),
The surface of the substrate 1 and the inner wall surface of the through-hole hole 3 are plated to form a conductive layer 2.

Next, after filling the holes 3 of the substrate 1 with the resin paste 4 using a roll coater (not shown), the resin paste on the surface of the substrate 1 is scraped off through a pair of upper and lower squeegees (not shown). Figure 2(b)).

Next, after hardening the resin paste 4, the resin paste 4 on the surface of the substrate 1 is removed by polishing using a puff polisher, a belt polisher, etc. (FIG. 2(C)). Next, as shown in FIG. 2(d), after forming an etching resist layer 5 on the surface of the substrate 1, the exposed portion of the conductive layer 2 is removed by etching using the etching resist layer 5 as an etching mask (see FIG. 2(e)).
)). Next, the resin paste 4 and the etching resist layer 5 are peeled off to obtain a desired circuit pattern.

(Figure 2(f)).

[Problems to be Solved by the Invention] The conventional method for producing through-hole printed wiring boards has the following drawbacks.

(a) After curing the resin paste 4, when removing the resin paste 4 on the surface of the substrate 1 by using a puff polisher or belt polisher, if the puff or belt is locally worn. Since the resin paste 4 on the surface of the substrate 1 is not removed and remains, short circuits often occur in the circuit pattern and copper remains.

In order to prevent this, methods have been used to increase the amount of polishing by providing two or three puff or belt polishing sections or by making the puff or belt rougher. Since the amount also increases, the plating thickness of the conductive layer 2 at a part of the corner of the hole 3 becomes thinner, which poses a problem in terms of reliability.

(b) Another method is to provide two or three stages of squeegees for scraping off the resin paste 4 on the surface of the substrate 1 in order to minimize the amount of resin paste 4 adhering to the surface of the substrate 1. However, the squeegee can be used in two or three stages.
As the number of holes 3 increases, the resin paste 4 inside the holes 3 is also scraped off.
The disadvantages were that the coating became thin and the coating did not adhere. As a result, a portion of the corner of the hole 3 is etched away, which is a problem in terms of both yield and reliability.

An object of the present invention is to provide a method for manufacturing a printed wiring board that eliminates such conventional drawbacks.

[Differences between the invention and the prior art] In contrast to the above-described conventional printed wiring board manufacturing method, the present invention fills the holes in the substrate with the resin paste 4 and then chemically removes the resin paste 4 that adheres to the surface of the substrate 1. It has an original content of being dissolved and removed.

[Means for Solving the Problems] The present invention includes a step of filling a resin paste into a hole of a printed wiring board in which a conductive layer is formed on the inner wall and surface of the hole, and then hardening the resin paste, and a step of hardening the resin paste, and a step of chemically dissolving and removing the resin paste; a step of forming an etching resist layer on the substrate surface; a step of selectively etching away the exposed portion of the conductive layer using the etching resist layer as an etching mask; The method of manufacturing a printed wiring board is characterized in that it includes a step of removing an etching resist layer.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1(a) to IJ).

(Example 1) First, as shown in FIG. 1(a), the surface of the substrate 1 and the inside of the hole 3 are plated with copper to form the conductive layer 2.

Next, as shown in FIG. 1(b), an alkaline removable resin paste 4 is filled into the holes 3 using a roll coater (not shown), and a pair of upper and lower squeegees are used to coat the resin on the surface of the substrate 1. After scraping off the paste 4, the resin paste 4 is cured. As the resin paste 4, a thermosetting type or an ultraviolet curing type may be used, but when using an ultraviolet curing type, it is necessary to sufficiently harden the resin paste 4 in the hole 3, and the amount of ultraviolet energy irradiation of about 1 to 2 J/cm2. Next, the substrate 1 is immersed in a 0.5 to 2% by weight sodium carbonate aqueous solution, and the resin paste 4 on the surface of the substrate 1 is removed with a rotating brush while being dissolved.
In order to remove the sodium carbonate aqueous solution on the surface of the blocking plate 1,
Thoroughly wash with water (Fig. 1 (C)). Alternatively, as another method, after dissolving the resin paste on the surface of the substrate 1 by immersing it in a 0.5 to 2% by weight aqueous sodium carbonate solution, the dissolved resin paste 4 is rotated while spraying water on both sides of the substrate 1. A method of removing with a brush may also be used.

Further, as the alkali, something other than sodium carbonate may be used, but it is necessary to perform sufficient water washing or neutralizing water washing so that no alkali remains on the surface of the substrate 1. Next, the surface of the substrate 1 is polished using a puff polisher or a belt polisher, and if necessary, acid treatment or permice polishing treatment is performed to smooth the surface (FIG. 1(d)). Next, an etching resist layer 5 is formed on the surface of the closing plate 1 by a screen printing method or a photoprinting method using a liquid resist or a dry film photoresist (FIG. 1(e)).
. After removing the exposed portion of the conductive layer of the substrate 1 by etching, as roughly shown in FIG. 1(U), the etching resist layer 5 and the resin paste 4 are peeled off to obtain a desired circuit pattern (FIG. 1(g)). ).

(Example 2) First, as shown in FIG. 1(a), the surface of the substrate 1 and the inside of the hole 3 are plated with copper to form the conductive layer 2. Next, Figure 1 (b
) with a roll coater.
(not shown) is used to fill the holes 3, and after scraping off the resin paste 4 on the surface of the substrate 1 with a pair of upper and lower squeegees, the resin paste 4 is cured. Both the thermosetting type and the ultraviolet curing type can be used as in 1. Next, the substrate 1 is immersed in a 0.5 to 2% by weight hydrochloric acid aqueous solution, and the resin paste 4 on the surface of the substrate 1 is removed with a rotating brush while being dissolved. Then, in order to remove the hydrochloric acid on the surface of the substrate 1, thoroughly wash it with water (Fig. 1 (C)). After dissolving the resin paste on the surface of 1,
A method may be used in which the dissolved resin paste 4 is removed using a rotating brush while spraying water on both sides of the substrate 1. Furthermore, as the acid, other than hydrochloric acid may be used, but the substrate 1
It is necessary to perform sufficient water washing or neutralizing water washing so that no acid remains on the surface. Next, the surface of the substrate 1 is polished with a puff polisher or belt polisher, and then acid treatment or permice polishing treatment is performed as necessary to smooth the surface (
Figure 1(d)). Next, as in Example 1, an etching resist layer 5 is formed on the surface of the substrate 1 (FIG. 1(e)).
First, the exposed portion of the conductive layer 2 of the substrate 1 is removed by etching.
(FIG. 1(f)), the etching resist layer 5 and resin paste 4 are peeled off to obtain a desired circuit pattern (FIG. 1(g)).

[Effects of the Invention] As is clear from the above description, according to the present invention, the resin paste on the surface of the substrate can be reliably removed, so printed wiring boards can be manufactured at high yield and at low cost. Since the parts can be reliably protected, a highly reliable printed wiring board can be manufactured.

[Brief explanation of drawings]

FIGS. 1(a) to (a) are cross-sectional views explaining an embodiment of the method for manufacturing a printed wiring board according to the present invention in the order of steps, and FIG.
) to (f) are cross-sectional views illustrating a conventional method for manufacturing a printed wiring board in the order of steps. 1... Printed wiring board 2... Conductive layer 3... Hole 4... Resin paste 5... Etching resist layer

Claims (1)

[Claims] (1) Filling the holes of a printed wiring board with a conductive layer formed on the inner wall and surface of the hole, and then curing the resin paste, and chemically curing the resin paste on the surface of the substrate. a step of dissolving and removing the conductive layer; a step of forming an etching resist layer on the surface of the substrate; a step of selectively etching away the exposed portion of the conductive layer using the etching resist layer as an etching mask; and a step of removing the resin paste and the etching resist layer. A method for manufacturing a printed wiring board, comprising the step of peeling and removing.