| 摘要 |
<P>PROBLEM TO BE SOLVED: To select a composition of Sn group solder, whereby the lifetime improvement can be expected at a low distortion speed under a temperature cycle test, because the occurrence of the considerable lifetime reduction is recognized under the temperature cycle test using Sn-3Ag-0.5Cu, wherein creep deformation is less likely to take place with respect to a large deformation accompanying a bent board and securing of high reliability is made difficult in conventional module structures, even though use of Pb-free solder is essential in environment problems and a power module requires soldering for its board with a large area. <P>SOLUTION: The effect of delaying crack development is found out at the low distortion speed, by adding 3 to 7% of In and 2 to 4.5% of Ag to the Sn group solder, and Sn-3Ag-0.5Cu-5In is selected as a typical stable composition, even at high temperatures. Furthermore, a method of partial coating of a resin to solder ends is indicated for high reliability. <P>COPYRIGHT: (C)2008,JPO&INPIT |
