| 摘要 |
A BGA package is mounted on a multi-layer printed wiring board having a plurality of electrodes arranged in a matrix form through a plurality of solder bumps. In the most externally-located electrodes, a lead wire is formed to extend from a portion of the most-externally-located electrode located inside of a polygon formed by connecting each of the centers of adjacent most-externally-located electrodes. Therefore, the solder bumps are prevented from coming off the most-externally-located electrodes because a portion of the most-externally-located electrode to which stress caused by an external shock is intensively applied is located in an outside of the polygon. Thus, a contact failure between the BGA package and the multi-layer printed wiring board is prevented.
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