| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that since ultraviolet irradiated from the surface of a solder resist is absorbed and attenuated on the way as it penetrates inside because a solder resist having larger thickness than usual is exposed by ultraviolet irradiation in a printed wiring board for large current, an inside solder resist can't obtain sufficient exposure amount compared with a surface portion, undercut occurs by allowing the lower portion of the solder resist to be eroded by sodium carbonate aqueous solution, adhesion is deteriorated, and a solder dam is peeled off in the severe case. SOLUTION: In one of processes of forming first and second solder resist layers, a non applied portion to which photosensitive solder resist ink is not applied is provided onto a region including a solder mounting land and its periphery at the time of application of the photosensitive solder resist ink. COPYRIGHT: (C)2011,JPO&INPIT
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