The Effect of Mechanical Vibration on Thermally Cycled, Lead-Free and Mixed Alloy Solder Joints

摘要

Unlike most consumer electronics, avionics experience temperature changes that range from sub-zero to > 100 °C in service that can change the solder joint microstruture. Avionics also experience severe vibration and shock during normal service, and the combination of temperature and vibration may negatively impact the performance of the solder joint. Further complications may arise when lead-free solder is used, both on original assemblies and during the repair of lead-tin solder joints. The effect of vibration on lead-free solder joints that have undergone thermal cycling has not been widely reported, especially for mixed solder compositions and hand repairs. Printed circuit boards containing lead-free and mixed solder compositions, along with some hand repairs, were thermally cycled between -65 °C and 150 °C for 1000 cycles. After thermal cycling, a resonant dwell at 5g served as a fatigue test to determine the vibration performance for the various solder compositions. The purpose of this study was to determine the vibration performance of the different solder compositions after undergoing thermal cycling and to determine how changes in microstructure related to the failure mode of the different components. Results indicate that ball grid array and 1206 resistor components failed electrical resistance checks during vibration testing, while larger DIP-16 and SO 16 components had no failures.