Recent advances in drop-impact reliability

This manuscript presents some of the research works performed by a consortium of companies for the studies of the drop-impact reliability of electronic components. The extensive works covers test methodologies and failure model. Under the test methodologies, the board level high speed cyclic bend test and the component level ball impact shear test were correlated with the board level drop/shock test using 23 groups of diverse solder joints. Under the failure model, the stress-strain characteristics of 4 solder alloys were generated for the medium strain rate regime (up to 300 s^-1); the S-N characteristics of 6 solder joints between the PCB fibre strains of 1x10^-3 to 3x10^-3 at bending frequency of 100 Hz were generated; the S-N characteristics of the solder joints as a function of bending frequency (from 30 Hz to 150 Hz) and test temperatures (-10degC and 25degC) were also investigated. The characteristics of crack propagation were correlated with the observed crack path in the solder joints. In addition, a robust solder joint design was proposed and validated.