Failure analysis of solder mounted on smartphone substrate

Abstract

In recent years, miniaturization of solder joints has progressed as performances of electronic devices advanced. This leads to more sever mechanical conditions on the solder joints than before, and requires an evaluation of their strength reliability with high accuracy. In this study, a simple estimation method for the fragility of solder joints on electric substrates in smartphones against dropping impact is proposed. First, the modal and frequency response analyses of substrates are performed to obtain the mode shapes that are assumed as dominant deformation shapes just after impacts. Then, a fatigue failure analysis of solder joints is conducted with referring to those shapes. The estimated results are compared with experimental results, and both results indicate similar tendency in terms of positions of failed solder joints.