Effects of test conditions on bending impact of lead free solder

Drop reliability of portable IT products such as PDA's, notebooks and mobile phone is issue with increase of using for lead free solder by environment regulation. Intermetallic compound formed at interface between lead free solder and pad is main cause of weakness on drop impact. To evaluate drop reliability, drop impact test methods is widely used by JEDEC standard, which is time consuming and expensive. In this study, we performed bending impact tests of a soldered joint as one of indirect test methods and studied the effects of variables, such as components size and types, aging treatments, bending variables, and number of tests by statistical analysis. Minitab software were used to conduct statistical analysis. From the bending impact results at different component size or type, p-values were smaller than 0.05, and we knew that this test method quantitatively could be represent bending impact reliability of lead free solder joints under given conditions. We could statistically distinguish the effects of thermal shock or aging treatment of solder joints by bending impact tests under given conditions. we know that proper plus amplitude range and minus amplitude are between 5mm and 10 mm, and minus 3 mm, respectively. Suitable frequency ranges were 2.5-10 Hz. Bending impact life of 10 tests was statistically equivalent that of 5 tests and we could select 5 tests instead of 10 tests.