Solder interconnects reliability subjected to thermal-vibration coupling loading

Experiments and finite element simulations are used to evaluate board-level reliability under vibration loading coupled with different temperatures (25 °C, 65 °C, 105 °C). The responses of the boards and solder interconnects are characterized, based on which the failure modes and failure life were studied and correlated with coupling conditions. Significant coupling influences are found on PCBs’ response, solder plastic behavior, the failure modes and life time of the solder interconnects. Studies indicated that the main root cause of these influences can be concluded as the temperature dependent materials behaviors of the assembly components. Elevated temperature within the range of 25–105 °C cause evident decrease of the PCB eigenfrequency, which will greatly affect the PCB amplitude of a fixed-frequency vibration test. The effect of temperature on solder interconnects can be deposed into two aspects, one is temperature induced change of applied loading (PCB responses), and the other is temperature induced change of solder behavior (alloy properties). Therefore, the stress and strain of solder interconnects in varied coupled tests performed as the combination outcomes from both varied PCB responses and varied materials behaviors of solder materials. The dominating factors are analyzed. Sever stress area are proposed to address the failure sites transform. Solder interconnects lifetime data condition are collected and fitted with each coupled condition.