Abstract: The influence of print circuit board design on solder joint reliability (SJR) of thin small outline package (TSOP) has been investigated in a specifically designed experiment. The SJR test board includes three layout parameters. The TSOP component has been soldered to the test board under surface mount process. Solder joints’ crack length subject to each design parameter has been measured after the samples went through thermal cycling from -40 to 85 ℃. The mechanism of solder joint crack has been discussed. In addition, two judgment criteria are chosen according to the crack length. The results show that SJR of TSOP can be improved by long size pad, organic solderability preservatives (OSP) surface finish and offset double placement.

Key words: failure mechanism, solder joint reliability (SJR), thin small outline package (TSOP)