| 摘要 |
PROBLEM TO BE SOLVED: To form reflowed solder like a smooth fillet to reduce the stress/strain in solder during operating of an electronic circuit device and improve the thermal fatigue life by adjusting the quantity of a solder paste at a board and making the pad diameter at the board larger than the bump diameter of an LSI chip. SOLUTION: Many bumps are provided on an electronic circuit device, pads 4 having a larger diameter than that of Au bumps formed on Al electrodes are formed at a board, Sn37Pb paste 2A is printed on the board and positioned so that bumps of an LSI are on Sn37Pb, heated to reflow, thereby forming Sn37Pb like a fillet smooth enough to avoid cracking, the solder quantity may be adjusted to form it like a smooth fillet, or pads 4 having a larger diameter than that of Pb3Sn bump 1B formed on Al electrodes are formed at the board and the same operation may be made.
|
