| 摘要 |
An improved process for making a printed circuit board of the type comprising solder-rooted pads and a solder-coated internal wall of each hole in the circuit board. The new process comprises the step of masking over a dry film, e.g. an alkaline ink film, after copper plating and before solder plating. In one embodiment of the invention, a selectively-plated thin layer of solder to act as a resist except on the areas defined by hole pads and barrels but is wholly free of solder which can melt and cause solder-migration problems under the surface of the printed circuit board.
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