Lifetime prediction of BGA assembles with experimental torsion test and finite element analysis

Electronic second level interconnect reliability characterization by accelerated thermal-cycling (ATC) test for long-term mission profile is costly and high time consuming. In order to reduce test duration, the torsion test was applied using some specific test parameters to reproduce the same failure modes found in ATC tests and in the field. To define the torsion test parameters, we carried out a complete design of experiments varying the values of temperature, torsion angle and dwell time. The test results indicate a strong dependence of the number of cycles to failure and the three torsion parameters. In this paper, we present the finite element analysis techniques applied to predict lifetime of ball grid array (BGA) assemblies under torsion test. The main objective is to interpret the torsion test program results and to develop a damage law for electronic interconnects under torsion test. The results suggest that solder joint damage under torsion test is induced by two different failure mechanisms: the damage generated by instantaneous plastic strain and the damage generated by creep plastic strain.