| 摘要 |
<p>It is an object to realize a distortion reduction fixing structure in a fixing structure between a protection plate member for protecting a BGA junction portion of a printed circuit board from external force and the printed circuit board. In this distortion reduction fixing structure, a counterbore (13) is made around a fixed axis through-hole (16) of a printed circuit board (4) for fixing a protection plate member (1) and its depth is not less than 1/2 of the thickness of the printed circuit board (4). When the printed circuit board (4) is fixed at the protection plate member (1) with an embedded bolt (3) on the side of a bolster plate (1) and a spring pressing stick-like nut (6) on the side of a heat sink (5), a major part of distortion due to flexure corrective force imposed on the printed circuit board (4) from the fixing portion is concentrated at an edge portion of the counterbore (13), so that big distortion does not spread to the junction portion of a bump (11) of a BGA package (2).</p> |
