| 摘要 |
A permanent solder mask is applied to the surface of a printed circuit board using a copper foil carrier. The solder mask preferably is one or two layers of a thermosetting resin e.g. epoxy resin (26). Selected circuit features are exposed by etching away portions of the copper foil (24) and removing the underlying thermosetting resin. Then, the remaining copper foil (24) is removed, leaving the solder mask on the surface of the printed circuit board.
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