Experimental investigation on the progressive failure mechanism of solder balls during ball shear test

The present study is aimed at establishing the mechanics foundation of solder ball shear tests for evaluating the solder ball attachment strength of BGA packages. In particular, the emphasis is placed on understanding the progressive failure mechanism during the ball shear test. In this paper, an experimental investigation is presented. Specimens with BGA solder balls are fabricated and a series of ball shear tests is conducted. The shear ram is stopped at various stages during the ball shear test. The specimens are cross-sectioned for SEM inspection. The observed failure modes are characterized and correlated to the corresponding shear loading curves. The current experimental results can lead to a profound understanding in the failure mechanism of solder balls under mechanical shear loading. Furthermore, the outcome of the present study may provide a valuable database for the validation of computational modeling.