Laser moiré interferometry for fatigue life prediction of lead-free solders

A laser moiré interferometry based technique to predict the fatigue life of Sn4.0Ag0.5Cu solder joints in a plastic ball grid array (PBGA) package when subjected to a typical accelerated thermal cycling (ATC) loading has been presented in this paper. The fatigue life is estimated by measuring the in-plane strains in the solder joints at various temperatures. The methodology can be used to predict the reliability of the package in a matter of few days as opposed to many months taken by an actual ATC test. The technique can be extended to include multiple temperature regimes in a single experimental setup thereby making it possible to estimate the fatigue life of solder joints when subjected to various ATC loading profiles in a very short duration.