Reliability of Pb-free BGA solder joints under random vibration

Alternating elastic and plastic strain or even creep was inevitably produced in the solder joints under thermal cycle, vibration or impact circumstance, and finally caused the fatigue failure of solder joints and electronic equipments. The fatigue life and its failure mechanism are always the interests to the reliability of solder joints. Generally, the low-cycle fatigue induced by thermal cycling is the major concern in the reliability of electronic packaging, while dynamic loading effects to solder joint fatigue life have not been thoroughly investigated. Actually, the interaction of the strain induced by dynamic loading and low cycle fatigue is going to accelerate the process of failure. Under certain circumstance, vibration and impact would like to be the main failure reasons. Also, comparing to the fact that alternating thermal strain induced by thermal cycle is just depended on temperature, strain in the joints in vibration circumstance is more depended on the components location in PCB, solder joint location in the array, size of solder balls, constraint positions and the other working circumstance. This paper is concerned with the reliability of lead-free ball grid array (BGA) packaging under random vibration including the effect of the location of BGA on the PCB and holding positions during tests. Special circuit was designed to detect the voltage of the BGA ball circuit and the real failure time of solder joints during tests.