| 摘要 |
PROBLEM TO BE SOLVED: To suppress adverse effects of warpage on a final package, by providing a plurality of conductive metal pads, which can be connected to a plurality of approximately spherical part of solder alloy, on the first plane of a printed circuit board, and permitting the pads to have different surface areas. SOLUTION: Each of four pads 501 at the center has a larger area than pads 503 in the vicinity of the edge. At the time of mounting solder balls to the metal pads 501 and 503, the solder balls are dispersed over the entire ball pads 501 at the center, which have larger contact areas to be wetted, and as a result, the the final height of the balls is lowered. Thus, the outer pads 503 separated from a reference plane due to warpage reduce coplaner value, and adverse effects of warpage us offset. Namely, the differentiated geometrical shape offsets natural deformation of the module and the effects of the package warpage is equalized. |
