JPS61176187A - Manufacture of printed wiring 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] [Technical field of invention] The present invention relates to a method of manufacturing a printed wiring board.

More specifically, the present invention relates to a method of manufacturing a through-hole plated printed wiring board by electroless copper plating.

[Technical Background of the Invention] Conventionally, many through-hole plated printed wiring boards have been manufactured by an electric steel plating method.

However, the manufacturing method using electric steel plating has problems in that mass production is difficult, the cost is high, and the process may be long.

[Object of the invention] This invention was made in view of the above-mentioned drawbacks of the electric steel plating method, and its purpose is to mass-produce through-hole plated printed wiring boards with stable quality through a relatively simple and short process. The purpose is to provide a manufacturing method that obtains the desired results.

[Example] Hereinafter, the present invention will be described in detail with reference to an example shown in FIG.

First, as shown in FIG. 1(A), a copper-clad laminate 3 is prepared by contacting copper foils 2a and 2b on the front and back sides of an insulating substrate 1,
A through hole 4 is formed in the portion where the through hole is to be formed by drilling or punching, as shown in FIG. 3(B). Next, the surfaces of the copper foils 2a, 2b and the through holes 4 are sealed with an active liquid 5 for electroless copper plating and a photosensitive film 7.7 as shown by dotted lines in FIG. In addition to protecting the hole walls, an etching resist for forming a circuit pattern is formed at required locations on the front and back sides of the copper-clad laminate 3. Note that instead of using a photosensitive film, the pore walls can also be protected by an ink hole-filling printing method or the like. After the etching process, the photosensitive film 7.7 and the etching resist are peeled off as shown in Figure (E), and a permanent resist 8 for protecting the circuit pattern is formed as shown in Figure (F). . This permanent resist 8 functions as a plating resist in the next plating process and as a solder resist when mounting electrical components. Electroless copper plating, that is, partial plating, is applied to both ends of the hole and inside the hole wall to form a deposited copper layer 9.

As is clear from the description of the embodiments described above, according to the present invention, by forming through holes by electroless plating, a uniform plating thickness can be obtained, mass production is possible, and a large amount of In addition to reducing costs, since the copper-clad laminate is used as a material, stable circuit formation and strong copper foil adhesion make it possible to manufacture high-precision, high-quality through-hole plated printed wiring boards.

[Brief explanation of the drawing]

FIGS. 1A to 1G are process diagrams for explaining the present invention. In the figure, 1 is an insulating substrate, 2a and 2b are copper foils, 3 is a copper-clad laminate, 4 is a through hole, 5 is an active liquid, 7 is a photosensitive film, 8 is a permanent resist, and 9 is a precipitated steel layer. .

Claims (1)

[Claims] a step of forming through holes in the copper clad laminate; a step of depositing active nuclei of electroless copper plating on the entire surface of the copper clad laminate including the walls of the through holes by activation treatment; and a photosensitive film, etc. a step of forming an etching resist that protects the hole wall of the through hole and a predetermined circuit pattern with a protective means; a step of etching to form the predetermined circuit pattern; and a step of forming a permanent resist. and the step of removing the protective means and forming a deposited copper layer on the wall of the through hole by electroless copper plating.