Patent ID: 8101514

Claim:
A method of manufacturing a semiconductor device comprising the steps of: (a) preparing a semiconductor chip and a package substrate, said semiconductor chip having a main surface and first pads on said main surface, said package substrate having a first surface, a second surface opposing to said first surface, second pads on said first surface and third pads on said second surface; (b) mounting said semiconductor chip on said package substrate, such that said main surface of said semiconductor chip faces with said first surface of said package substrate and said first pads of said semiconductor chip and said second pads of said package substrate are electrically and mechanically connected to each other by solder bumps not including Pb; (c) providing an under-filling resin between said semiconductor chip and said package substrate to surround said solder bumps; and (d) after the step (c), forming solder balls on said second surface of said package substrate, such that said solder balls and said third pads of said package substrate are electrically and mechanically connected to each other, said solder balls not including Pb; wherein both of said solder balls and said solder bumps have Ag, Cu, and Sn, and wherein a mass ratio of Ag in said solder bumps is lower that of said solder balls.