| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively and appropriately connect a warped or uneven subordinate substrate or mounting parts, such as electronic components, etc., to a mother board. SOLUTION: On an electronic component 1, the wetting areas between solder grains 4 and the electrodes of a subordinate board 3 are changed by opening electrode openings 8, having different sizes through a solder resist covering the surfaces of the electrodes 8, according to the then warping state of the board 3 immediately before the substrate 3 is connected to a mother board 2 through the solder grains 8. Namely, the openings 8 on the electrodes nearer to the mother board 2 are formed in larger sizes and the openings 8 farther from the substrate 2 are formed in smaller sizes. When solder grains 4 having the same size are put on the openings 8 and solidified after the grains 4 are heated to a temperatures higher than their melting points, the wetting areas and heights of the solder grains 4 on the smaller openings 4 become narrower, and higher and the heights of the solder grains 4 on the larger openings 8 become lower. Therefore, the subordinate board 3 and mother board 2 can be connected appropriately and inexpensively to each other by absorbing the warping and unevenness of the board 3 by the heights of the solder grains 4. |
