JPS59178788A - Method of producing 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 the relationship between the thickness of a liquid photosensitive Menki resist and the thickness of a conductor in fully additive circuit board manufacturing.

In recent years, full-additive methods have attracted attention as a low-cost and highly reliable method for manufacturing circuit boards, and some of them have been put into practical use.

However, it is limited to medium-density patterns with one-by-one kneading between bins. It is no exaggeration to say that when a circuit board is formed using a fully additive method, the density of the circuit board is determined by the Menkilenost resolution. Conventionally, this method of mesh registration screen printing has been used, making it difficult to produce single-density patterns. In addition to the problem that fine printing is difficult, the printing method also causes the edges to sag, resulting in a decrease in beer strength per conductor 1.

To explain with reference to FIG. 1, the apparent 1] of the conductor 3 is shown as b, but this beer is held in close contact with the substrate 1 only at the part a. To increase. That is, since the plating grows and precipitates in the lateral direction to the same extent as the growth thickness of electroless plating, the value of ly'a becomes thick. This situation is shown in FIG. The finer the pattern, the thicker the conductor must be in order to maintain a constant conductor resistance (the overall resistance is determined by the volume of the conductor), and with this screen printing resist method, it is difficult to use a high-density substrate. This was one of the reasons why it could not be manufactured. Furthermore, solder bridges caused by solder dipping in the subsequent process are more likely to occur as the solder becomes finer, and this must also be prevented. As a solution to such conventional methods, the present inventors have made it possible to ensure the first building strength, that is, a#b, by using a liquid photosensitive resist as a metal resist. Furthermore, the inventors found that the second solder bridge can also be solved by forming the resist thickness to be equal to or larger than the required conductor circuit thickness, leading to the present invention. Referring to FIG. 6, the thickness C of the liquid photosensitive resist 4 must satisfy the relationship C≧d with the thickness d of the conductor circuit 6. C can be adjusted by coating conditions, for example, in the case of a curtain flow coater, resist solid content concentration, viscosity, belt speed, curtain slit width, etc.

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

Example: Tenman Bakelite Paper Epoxy Board EL-8182
After drilling through holes using an NC drilling machine,
3002μ chromic acid, 200? / in sulfuric acid at 60℃1
The entire surface was roughened by immersion for 5 minutes. After washing with water, it was treated with a sensitizer H8-10i B manufactured by Hitachi Chemical Co., Ltd. for 5 minutes, and further immersed in an accelerator manufactured by Hitachi Chemical Co., Ltd. for 2 minutes. After washing with water and drying at 120°C for 30 minutes, apply a curtain coater FL- manufactured by Iwata Yaiki Co., Ltd.
86Fk is used, and urethane acrylate modified polybutadiene resin (UVS manufactured by Nippon Soda), which is a liquid photosensitive resist, is used.
-400) was applied to a thickness of 60μ. The conductor pitch interval of the pattern was 200 μm. The curtain coating conditions at this time were as follows.

UVS' -400 viscosity, 1.5 poise solid content concentration = 38 Solvent Nibutyl cell solve curtain coater Belt speed: 100 m/a
After curtain coating, the film was dried at 80° C. for 30 minutes, and the thickness of the coated film inside the substrate was actually measured to be 30 μ±2 μ.

Further, the opposite side was coated under the same conditions. Next, both sides were exposed with a mask and developed with trichlene to form a circuit pattern. Next, the thin material was immersed in an electroless M Ni -P plating bath S-680' manufactured by Kanigen Co., Ltd. for approximately 1μ of N1-P'i, and then the thin material was immersed in an electroless plating bath MK-450 manufactured by Muromachi Kagaku Co., Ltd. for 15 times. Got plated. Next, heat treatment was performed at 180°C for 20 minutes to promote polymerization of the resist, and N1-px
We aimed to improve the adhesion strength of cu to the substrate. Next, the work surface was activated with 5-layer I (2S○4), and after washing with water, fast thermal electrolysis [
The thick plate was first plated using plating (manufactured by World Metal Co., Ltd.). The plating time was changed, that is, the plating thickness was changed, and the beer strength (on the basis of conductor b'1) and the strength were confirmed.

Table 1 As shown above, b/a exceeds 1! If 7b≧a, that is, the plating thickness exceeds the resist thickness, the plating will rapidly grow in the direction of the lateral force of the conductor pattern, and the beer strength against the conductor core will decrease.

This tendency seems to increase as a becomes smaller, that is, as the density increases.

Also, solder bridges become brittle when b/a exceeds 1.

The relationship between the resist thickness and the plating thickness has been shown above for the full additive method using a liquid photosensitive resist, and the effects of the present invention are clear.

It can be said that the present invention is indispensable for a fully additive process that is high-density, inexpensive, and highly reliable.

[Brief explanation of the drawing]

Figure 1: A cross-sectional view of a fully additive circuit board using a conventional resin) Figure 2: A cross-sectional view of a full additive circuit board using a conventional resist Figure 3: A cross-sectional view of a fully additive circuit board using a conventional resin) Full additive circuit board & O cross section

Claims (1)

[Claims] Conductor circuit is applied to the circuit board by liquid photosensitive resist 7)K mask UV (ultraviolet rays) exposure and development to form a pattern, U■ hard hardened tube plating resist, and conductor is completely formed by plating on the development removed part. A method for manufacturing a circuit board, characterized in that, in a fully additive method, the thickness of a liquid photosensitive resist after UV curing is equal to or thicker than the required conductor circuit thickness.