Effect of different temperature cycling profiles on the crack initiation and propagation of Sn-3.5Ag wave soldered solder joints

摘要

Temperature cycling of a test board with different electronic components was carried out at two different temperature profiles in a single-chamber climate cabinet. The first temperature profile ranged between -55 and 100 ℃ and the second between 0 and 100 ℃. Hole mounted components and secondary side SMD components were wave soldered with an Sn-3.5Ag alloy. Joints of both dual in line (DIL) packages and ceramic chip capacitors were investigated. Crack initiation and propagation was analysed after every 500 cycles. In total, 6500 cycles were run at both temperature profiles and the observations from each profile were compared. For both kinds of components analysed, cracks were first visible for the temperature profile ranging between -55 and 100 ℃. For this temperature profile, and for DIL packages, cracks were visible already after 500 cycles, whereas for the other temperature profile, cracks initiated between 1000 and 1500 cycles. The cracks observed after 1500 cycles were visibly smaller for the temperature profile ranging between 0 and 100 ℃, concluding that crack initiation and propagation was slightly slower for this temperature profile. For the chip capacitors, cracks were first visible after 2000 cycles.