Vibration reliability of SMD Pb-free solder joints

This study presents a method to predict lifetime of SMD lead free solder joints submitted to vibrations. An experimental method is presented to test chip resistors under vibrations. A specially designed testboard allows testing several specimens simultaneously. The time to failure is electrically detected. The experimental method is simulated using the Finite Element Method (FEM) in order to correlate the stress level calculated on solder joints with the experimentally observed time to failure. The obtained results show that the Printed Circuit Board (PCB) has critical zones where the components fail at first. It is noticed that the damage on solder joint is mainly caused by the warpage of the PCB. On the contrary, the damage caused by the high local acceleration levels on the testboard is insignificant compared with the stress level caused by the warpage of the board.