JPS638194B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a printed wiring board.

Conventionally, the manufacturing method for selectively plating printed wiring boards uses a method of masking unnecessary parts of plating with a plating-resistant resist layer, and this mask is used to improve operability and processability in each manufacturing process. A method of forming a screen using a screen original (hereinafter referred to as a mask original) having a plurality of mask patterns is used in consideration of effective utilization of human and material resources.

At this time, it was common practice to arrange the same mask patterns side by side.

For this reason, it is difficult to control the plating thickness uniformly in printed wiring boards for electronic watches, which require a large area to be selectively plated and which require a circuit design with a large difference in area between the front and back surfaces. This method has the drawback of wasting difficult and expensive precious metals and hindering the provision of inexpensive printed wiring boards.

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

According to the present invention, a mask of a plating-resistant resist layer having a mask pattern on the front and back surfaces is sequentially printed on a printed wiring board in which circuit patterns on the front and back sides are formed in pairs on the same surface as a plurality of sets. Manufacture of a printed wiring board characterized by using a selective plating process consisting of a process of printing from the front and back sides of the substrate and a process of plating precious metal on areas other than those covered with a mask of a resist layer with anti-plating properties. method is obtained.

The present invention will be explained below with reference to the drawings.

1 and 2 show an embodiment of the present invention, and FIGS. 1a and 1b show a state in which a noble metal plating layer 2 is selectively applied to the front and back surfaces of a printed wiring board 1, respectively.

Reference numeral 3 indicates a front mask layer, 4 indicates a back mask layer, and 5 indicates a lead as a conductive path used when applying the noble metal plating layer 2 to the circuit pattern 6 on the front surface and the circuit pattern 7 on the back surface.

Using a well-known method, holes for through-hole connections (not shown) are drilled, and the walls of the holes are plated with copper.
After forming an image of a circuit pattern with a photosensitive resist, unnecessary portions of copper other than the circuit pattern are removed by corrosion to form a circuit pattern 6 on the front surface and a circuit pattern 7 on the rear surface.

At this time, the circuit pattern 6 on the front surface and the circuit pattern 7 on the back surface developed in a projected pattern on the printed wiring board 1
A plurality of pairs are arranged and formed on both sides.

Next, a front mask layer 3 having a front mask pattern is printed on the circuit pattern 6 on the front side, and a back mask layer 4 having a back mask pattern on the circuit pattern 7 on the back side.

Next, in a noble metal plating bath (not shown), the noble metal plating layer 2 is placed on the lead 5 on the parts other than the parts covered with the front mask layer 3 and the back mask layer 4 formed of a plating-resistant resist layer. The required amount of plating current is applied as described above.

As described above, when plating precious metals according to the present invention, the amount of current applied to the upper and lower surfaces of the printed wiring board can be controlled equally, so the thickness of the precious metal plating can be made uniform, and the consumption of precious metals can be suppressed. It can be very effective.

[Brief explanation of the drawing]

FIGS. 1A and 1B and FIG. 2 are plan views showing an embodiment of the present invention. 1...Printed wiring board, 2...Precious metal plating layer,
3... Front mask layer, 4... Back mask layer, 5...
...Lead, 6...Circuit pattern on the front side, 7...Circuit pattern on the back side.

Claims (1)

[Claims] 1. In a method for manufacturing a printed wiring board having circuit patterns on both sides, a plurality of circuit patterns on the front side and a circuit pattern on the back side of the printed wiring board are arranged on one side of the same substrate, and a plurality of circuit patterns on the front side and the circuit pattern on the back side are arranged on one side of the same substrate, and forming the circuit pattern on the back surface at a position facing the circuit pattern on the front surface, and forming the circuit pattern on the front surface at a position opposite to the circuit pattern on the back surface on the other surface of the substrate. a step of applying a mask of a plating-resistant resist layer to the circuit pattern; and a step of selectively applying plating to areas other than the portions covered with the mask of the plating-resistant resist layer. 1. A method for manufacturing a printed wiring board, comprising a step of attaching the printed wiring board.