| 摘要 |
PROBLEM TO BE SOLVED: To prevent a mounted electronic component from the state not connected normally to an external electric circuit for a long time by preventing separation between a nickel-plated layer and solder. SOLUTION: A wiring board includes an insulating board 1, a wiring conductor 2 formed on the board 1, a nickel-plated layer 9 deposited on the wiring conductor 2, and solder 7, 8 bonded on the nickel-plated layer 9. The nickel- plated layer 9 has a trench formed along a nickel grain boundary and having a depth of 0.2μm or less.
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