Abstract: In this paper, the mechanical behaviour of Surface Mount Technology (SMT) solder joints under thermal cycles has been analyzed in the viscoelastic theory , and this has been verified by experiments on the simulated specimen. The results show that the stress of SMT solder joints under thermal cycles depends on the temperature history of thermal cycle, and there is a strong influence of the time effect, variating temperature rate and dwell time on the mechanical behavienr of SMT soldered joints under thermal cycles. With a rise in cycle temperature and the increase of dwell time, a notable stress relaxation will take place in SMT soldered joints.

Key words: 钎焊接头, 热疲劳, 软钎焊