| 摘要 |
PROBLEM TO BE SOLVED: To prevent the disconnection of wiring due to the solder cracks developed between connection pads by the change of temperature after connection of the wiring board having great difference in thermal expansion coefficient. SOLUTION: A protruding part 4, having the surface where soldering is impossible, is formed protuberently on the part inside the outer circumference of each connection pad 3 of a ceramic board 1. A solder ball 6 is soldered on the pad 3 using a solder ball 5 having the melting point lower than the solder ball 6, and a terminal is formed. As a result, a void G is formed on the surface of the protruding part 4 and the side face 4b. The void G remains even when the board 1 is soldered to a resin printed board between each connection pad of both wiring boards. Cracks are hardly generated even when shearing force worked along the main surface by the difference in thermal expansion coefficient of both wiring boards. Also, even when cracks K are generated and they develop, they stop at the void G, and disconnection of wire can be prevented. |
