The effect of iso-thermal aging on vibrational performance of SAC 105 and 305 alloys

Ball grid array (BGA) packages have rapidly become the popular choice of manufacturers in the semiconductor industry over the past decade. The characteristics of BGA packages in a vibration environment have a deleterious effect after long term isothermal aging. The effectiveness of this characteristics was demonstrated with promising results through vibration testing of SAC 105 and 305 alloys. This experiment focuses on the vibration fatigue life of 10 mm, 15 mm and 19 mm BGA solder-joints at aging temperatures of 55°C for 6, 12 and 24 months. The deleterious effect of the on the characteristic fatigue lifetime is reported. The results show that the aging time has a direct impact on the total time to failure. The results show that the Time-To-Failure (TTF) of the solder joint decreases with aging. A step stress test approach was taken in selecting a vibration profile for the study in order to reduce the duration of the test with most failures and as to record the failure more precisely over aging across 6,12 and 24 months. The paper concludes with discussion of the deterioration intensity aging has on SAC alloys and the change in reliability over time. The results obtained in this work show that there is a significant deleterious effect on the mechanical strength of SAC alloy solder balls during elevated temperature aging. The data demonstrate that the low-silver-content alloy (SAC105) is more sensitive to elevated temperature aging.