| 摘要 |
The printed circuit board is produced without soldering lands around the contacting, supporting or interconnecting holes of a simple faced, double-faced or multilayer circuit. The inner wall of the hole is covered with a copper layer which extends only until the free surfaces of the naked board, i.e. levels that surface, or does not fully extend until this level. The said layer is covered with a tin-lead metallization layer which services as a soldering link element. The solder mounts towards the wire or pin of the soldered component but does not touch nor spoil the free, insulating surface of the support. One necessary condition of the making process of the board is the precise, clean, proper and sharp drilling of the holes.
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