Investigation of lead-free BGA solder joint reliability under 4-point bending using PWB strain-rate analysis

Board level solder joint reliability was evaluated using a 4-point monotonic bending test on different BGA package assemblies, including a 51 × 51 mm 2400 CBGA and a 40 × 40 mm 1517 PBGA. The edgebond epoxy was applied between the package samples and solder-attached printed wiring boards (PWBs). During the bending test, the PWB strain, bending force and daisy-chain resistance were monitored in real time. The daisy-chain resistance and PWB strain-rate during the bending test were cross-referenced for detailed comparison. The test results indicated that the PWB strain-rate showed an obvious change at the moment of package failure. The PWB strain-rate can be a useful monitoring method for detecting the onset of the solder joint failure during the monotonic bending test.