| 摘要 |
This invention provides a printed wiring board having an intensified drop impact resistance of a joint portion between pad and solder. An electrode pad comprises pad portion loaded with solder ball and a cylindrical portion projecting to the solder ball supporting the pad portion. An outer edge of the pad portion extends sideway from a cylindrical portion so that the outer edge is capable of bending. If the outer edge bends when stress is applied to the solder ball 30, stress on the outer edge of the pad portion on which stress is concentrated can be relaxed so as to intensify the joint strength between an electrode pad and solder ball.
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