FATIGUE LIFE ESTIMATION OF SOLDER JOINTS IN SMT-PGA PACKAGES

The fatigue life estimation of solder joints is one of the most critic al requirements in the development of reliable electronic components. In this study, we first examined a constitutive model for Sn63-Pb37 so lder based on the results of material tests. It was confirmed that the behavior of the solder material can be expressed by the elastic-creep constitutive equations when the strain rate was low. Secondly, elasti c-creep stress analysis was carried out for the solder joints of a SMT -PGA (surface mount technology pin grid array) package. The location o f the failure predicted by the analytical results agreed well with tho se of the thermal cycle tests (TCT). It was shown that the fatigue lif e estimation of solder joints based on the present method is satisfact ory for engineering purposes.