| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic circuit unit, in which the stripping of solder from a ball becoming the reference for mounting a circuit board on a mother board is eliminated. SOLUTION: In the electronic circuit unit, a ball 6 which is to become the reference for mounting a circuit board 1 on a mother board 8 is formed of a resin ball part 6a and a solder film 6b provided on the outer surface of the ball part 6a and the ball 6 is soldered to the land part 3 of the circuit board 1. When the resin ball part 6a is used in the ball 6, the ball part 6a of the ball 6 has a thermal expansion coefficient equivalent to that of the circuit board 1 or to that of the mother board 8, when temperature cycle test is performed. Consequently, the ball 6 can follow up the thermal expansion coefficient of the circuit board 1 or of the mother board 8; and since stress is reduced between the ball 6 and the circuit board 1 and between the ball 6 and the mother board 8 without the stripping of solder is obtained. COPYRIGHT: (C)2005,JPO&NCIPI
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