JPS60160697A - Method of producing printed 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 of manufacturing a printed wiring board.

As the devices into which printed wiring boards are incorporated become smaller,
There is a need for smaller sizes and higher densities with closer distances between printed circuits.

When manufacturing printed wiring boards using an additive method such as the CG-4 method, an adhesive layer and a plating resist layer are sequentially provided on an insulating substrate, and then copper plating, etc. is formed on areas other than the resist by electroless plating. ing. This manufacturing method usually causes a phenomenon in which copper plating etc. precipitates and grows on the surface of the plating resist layer, which reduces the insulation resistance between the printed circuits and causes short-circuit defects. Countermeasures for high-density products are an important technical issue.

In order to improve these drawbacks, insulating substrates have traditionally been
A borohydrofluoric acid solution was used as the roughening liquid to roughen the adhesive layer, but this was replaced with a chromic anhydride sulfuric acid solution, which made it possible to reduce the number of defects. Ta. However, by using a chromate-sulfuric acid solution as a roughening solution, short-circuit defects etc. could be reduced, but on the other hand, the soldering heat resistance of printed circuits decreased, and in the case of insulating substrates with small through holes. had the disadvantage that the speed of plating inside the through ball was slow.

The present invention aims to improve the above-mentioned drawbacks and provide a method for manufacturing a printed wiring board that can improve solder heat resistance and the like.

In order to achieve the above object, the present invention sequentially forms an adhesive layer and a plating resist layer on an insulating substrate containing a plating catalyst, then roughens the adhesive layer with an anhydrous chromic acid sulfuric acid solution, and then removes the adhesive layer. In a printed wiring board manufacturing method in which a circuit is formed by dipping an insulating substrate in an electrolytic plating solution, the insulating substrate after forming a plating resist layer is heat-treated, and then immersed in a chromic anhydride-sulfuric acid solution to form an adhesive layer. The present invention provides a method for manufacturing a printed wiring board, which is characterized by roughening the surface of the printed wiring board.

Hereinafter, the present invention will be explained based on examples.

First, an adhesive containing a plating catalyst is applied to an insulating substrate such as a paper-phenol resin base material or a paper-epoxy resin base material containing a plating catalyst such as palladium to form an adhesive layer. Next, through holes are formed in the insulating substrate after the adhesive layer has been removed by punching or the like.

Note that the through hole may not be provided. After providing through holes in the insulating substrate, the through holes are subjected to seeder treatment to adhere a plating catalyst inside the through holes. After seeding, a plating resist is printed on the surface of the insulating substrate. Then, the insulating substrate provided with the adhesive layer and the plating resist Ill is heat-treated under predetermined conditions. The heating conditions are such that the temperature is 140° C. or higher and the time is 30 minutes or longer. The insulating substrate is heated and immersed in a chromic anhydride-sulfuric acid solution to roughen the adhesive layer. Anhydrous chrome! As a sulfuric acid solution, the composition is 0r0320~60g/j, 1-1
．． So, 150-500 ml/1, and NaF1
The liquid temperature is preferably 30°C to 45°C. After roughening the adhesive layer, the insulating substrate is immersed in an electroless copper plating solution to deposit copper plating at predetermined locations to form a printed circuit.

That is, according to the above embodiment, before roughening the adhesive layer laminated on the insulating substrate with an anhydrous chromium sulfuric acid solution,
Since the surface of the adhesive layer is heated, the adhesive layer is warmed in advance, and roughening by the anhydrous chromic acid/sulfuric acid solution is effectively performed, and appropriate irregularities are generated on the adhesive layer. Therefore, the adhesion between the adhesive layer and the printed circuit made of the stepped copper plating layer on this surface is improved, the solder heat resistance of the printed circuit is improved, and the plating precipitation rate inside the through hole is improved. is faster, reducing manufacturing time.

In addition, anhydrous chromium 11111ii! The temperature of the acid solution is preferably in the range of 30°C to 45°C; if it is lower than 30°C, the roughening time of the adhesive layer will be longer; if it is higher than 45°C, the roughened surface will be smooth. (j
This has the disadvantage that the solder heat resistance obtained by the heat treatment is reduced.

Next, the results of investigating the heel strength, solder heat resistance, and plating adhesion of through-holes for the embodiments of the present invention and conventional examples are shown in the table below. Solder heat resistance indicates the time it takes for the printed circuit to peel or bulge when the printed wiring board is immersed in a solder melt at 260°C.Also, the plating adhesion of through-holes indicates the time it takes for the printed circuit to peel or bulge when immersed in a solder melt at 260°C. The plating time required for the resistance of the through hole to become 0.1 iΩ when immersed in an electrolytic copper plating solution is shown.

In addition, Example 1) is a) insulating substrate: ACL-141 manufactured by Chinoku Hitachi Chemical Co., Ltd., in which an adhesive layer is laminated on a palladium-containing 21-ril rubber/phenol resin substrate; b) plating resist layer : Screen print an ink for plating resist (1-IGM-028K-1 manufactured by Hitachi Chemical Co., Ltd.) on the above insulating substrate.

C) Heat treatment: 160''G, 60 minutes d) Roughening treatment: Warm U40'CO) Roughening Pa (CrO,730Q/Y, concentrated sulfuric acid 300 tall/1, NaF2O9/1) in Soak for 12 minutes.

Manufactured under the following conditions. Furthermore, Example 2)
In Example 1), Article 4!4.0) was heated to 160°C and 30°C.
In Example 3), arrival C) is 150' in Example 1).
In Example 4), the blackness of the roughening liquid under condition d) in Example '1) was 35°C, and in Example 5), the blackness was 35°C under condition d) in Example 1). In Example 6), the temperature of the roughening liquid in Condition d was 50°C in Example 1, and in the conventional example, Condition C) was omitted in Example 1. They are manufactured under these conditions.

As is clear from the table, according to the present invention, compared to the conventional example, the solder heat resistance is 2.6 times or more, the through-hole plating adhesion is about 63%, or the speed is 1.6 times or more. The plating has precipitated and all properties have improved.

In addition, those whose roughening liquid temperature is in the range of 30°C to 45°C have approximately twice the soldering heat resistance and 2.5 times the through-hole plating capacity than those outside that range. It is clear that the roughening liquid in the former temperature range further improves the properties.

As described above, according to the present invention, by performing heat treatment before roughening the adhesive layer, solder heat resistance and through-hole plating (= I fi i! l erosion) can be improved. is obtained.

Patent applicant: Hitachi Capacitor Co., Ltd.

Claims (1)

[Claims] (1) After sequentially forming an adhesive layer and a plating resist layer on an insulating substrate containing a plating catalyst, the adhesive layer is roughened with an anhydrous sulfuric acid solution, and then the insulating substrate is coated with an electroless plating solution. In a method for manufacturing a printed wiring board in which a circuit is formed by dipping, the insulating substrate after forming the plating resist t-S is heat-treated, and then immersed in an anhydrous chromic acid-sulfuric acid solution to roughen the adhesive layer. A method for manufacturing a printed wiring board, characterized by: