JPS62232994A - Manufacture of 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] [Field of Application in the Ordinary Industry] The present invention provides an economical and workable method for selectively depositing electroless plating only on necessary areas such as through holes using a copper-clad laminate. The present invention relates to a method of manufacturing a printed circuit board with excellent performance.

[Conventional technology]

Conventionally, the mainstream method for manufacturing printed circuit boards has been the etched foil method.

For example, as shown in Figures 2(a) to (e), (1) through-holes are made in a subtractive copper-clad laminate, excess copper is dissolved and removed by etching, and a solder resist film is formed. A printed circuit board obtained by forming a wafer is well known.

(2) In the invention of Japanese Patent Publication No. 58-6319, after dissolving and removing unnecessary copper foil of a laminated board in which a catalyst layer is formed on the hole wall surface and the copper foil surface, electroless A method of manufacturing a through-hole printed board by forming a plating film has been proposed.

[Problem that the invention seeks to solve]

However, in the conventional method (1), a large amount of copper is dissolved and removed, and the process is complicated. Therefore, method (2) can be considered as a rational method, but the plating coverage on the steel foil circuit tends to be poor in the electroless plating process. In particular, non-precipitation phenomena of electroless plating were often observed in microcircuit parts that are not connected to through holes.

The object of the present invention is to manufacture a printed circuit board with good plating coverage in which a catalyst is applied only to the portions that require plating.

[Means for solving problems]

In order to solve the above problems, the method for manufacturing a printed circuit board of the present invention includes the following steps a) to e): a) step of drilling through holes at predetermined positions in a double-sided copper-clad laminate; b) through-holes. Step of catalytically treating the inside of the hole C) Step of forming the desired pattern by etching d) Step of masking the non-necessary portions with resist e) Step of selectively electroless plating only the inside of the through-hole and the desired pattern portion Step b) in a printed circuit board manufacturing method sequentially comprising
It is characterized by including a step of applying an electroless plating catalyst to the surface of the copper foil between and C).

Note that all commercially available laminates can be used in the present invention. This time, we used a glass epoxy copper-clad laminate. In addition, the thickness of the copper foil can be either 18 or 56.70 μm, which are commonly available.
18 μm was used as it is suitable for forming high density circuit spacing. Next, as a method for making holes, punching using a drill and a die can be considered, but in the present invention, holes were made using a drill to form uniform through holes. Further, as a method of applying an electroless plating catalyst to the copper foil, treatment with a well-known plating catalyst treatment solution such as AT-80 solution manufactured by World Metal Co., Ltd. or Red Schumer manufactured by Nippon Kanigen Co., Ltd. can be mentioned.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Example 1 Figures 1 (a) to (e) show the present invention in the order of steps. In the same IE4(a), the thickness of the copper foil 2 is 18 μm.
A glass-epoxy copper-clad laminate 1 is shown. Holes 3 for inserting components necessary for the circuit and for conducting between the front and back sides were drilled in the laminate as shown in FIG. 2(b). Next 6
The laminate was immersed in a 3% Dipsol solution at 0° C. for 5 minutes to degrease it. Furthermore, the copper surface was soft etched by immersing it in 20011/1% ammonium persulfate aqueous solution at room temperature for 3 minutes, and after immersing it in 5% sulfuric acid at room temperature for 2 minutes to dissolve the scum on the copper surface, hole 3 was filled with copper plating film. After pre-dipping in 20% MCI for 1 minute, it was immersed in a 60 c c / l s H8101B aqueous solution manufactured by Hitachi Chemical Co., Ltd. at room temperature for 10 minutes to adsorb catalyst 4 on the surface of the laminate. After that, use the Sibley accelerator.
Activation treatment was performed at 20° C. for 6 minutes at 19°C. Next, the same figure (
5 in AT-80 made by World Metal Co., Ltd. at 60℃ as shown in C).
The copper foil was immersed for a minute to form a catalyst Wt5 on the copper foil. Next, as an etching resist, an alkali-soluble photocurable film resist was laminated, exposed and developed, and excess copper was removed using ferric chloride solution at 50°C and 40'''Be°. Buttering was performed by dissolving and removing the resist and peeling off the resist.Then, as shown in the same figure (d), using Taiyo Ink Co., Ltd. solder ink S-221, the laminated layers other than the through-hole area and the area where the plating was deposited were removed. A resist film 6 was formed on the surface of the plate.

・Copper sulfate 10/l/10 EDTA jar 2Na 30 fl/10 formalin (67%)
5 m4 / l・α, α1-bipyridyl
5ml/AO polyethylene glycol Q, 5/l
/1・Glycine 6 g/l・PH=
12.0 (Adjusted with NaOH) The above composition was immersed in an electroless steel plating bath at 72°C for 5 hours, and the strain shown in Figure (e) was coated with about 1
An electroless copper plating film 7 of 8 μm was formed.

At this time, the coverage of the copper plating was good, the copper plating was deposited with good selectivity even on the independent microcircuit parts, and there was no plating blistering.

Examples 2 to 8 Comparative Example 1 When the conditions for forming the catalyst layer 5 using *AT-80 in Example 1 were changed, the results were as shown in the table below.

Table 1 Relationship between AT-80 treatment temperature and time and the presence or absence of plating and blistering [Effects of the invention] As explained above, the method for producing a printed circuit board of the present invention involves applying an electroless plating catalyst to the surface of the copper foil. By doing so,
A printed circuit board with good copper plating and good adhesion was obtained.

[Brief explanation of drawings]

FIGS. 1(a) to 1(e) are longitudinal cross-sectional views of product constituent parts in the manufacturing method of the present invention, shown in the order of steps. Moreover, FIGS. 2(a) to 2(e) are longitudinal cross-sectional views of product constituent parts in the order of steps in the conventional method. In the above drawings, 1... Insulating laminate 2... Electrolytic steel foil 3... Hole 4... Catalyst layer 1 5... Catalyst Layer 2 6...Solder resist film 7...More than electroless copper plating film Sanritsu Industries Co., Ltd. figure

Claims (1)

[Claims] Each of the following steps a) to e) a) Step of drilling through-holes at predetermined positions in a double-sided copper-clad laminate b) Step of treating the inside of the through-hole with a catalyst c) Etching as desired A method for manufacturing a printed circuit board, which sequentially includes the following steps: d) masking non-required portions with a resist; e) selectively electroless plating only the inside of the through-hole and the desired pattern portion; Process b
A method for manufacturing a printed circuit board, comprising the step of applying an electroless plating catalyst to the surface of the copper foil between steps of ) and c).