Effect of different temperature cycle profiles on the crack propagation and microstructural evolution of Sn-3.8Ag-0.7Cu solder joints

Övrigt konferensbidrag, 2005

Temperature cycling of real electronic components was carried out in a systematic manner at two different temperature profiles and in a single-chamber Heraeus climate cabinet. The first temperature profile ranged between 55 C and 100 C and the second between 0 C and 100 C. Top-side SMD components (chip resistors and Ball Grid Arrays (BGA)) were soldered with Sn-3.8Ag-0.7Cu lead free solder paste. Crack initiation and propagation was analyzed after every 500 cycles for each temperature cycling profile. Totally, 6500 cycles were run at both temperature profiles. Finite element modeling (FEM) calculations, for the analysis of strain and stress of 1206 chip joints were used to corroborate the experimental work results, especially regarding the crack initiation sites. Cracks were firstly visible for the temperature cycling ranging between -55 C and 100 C. The cracks observed were also visibly smaller for the temperature profile ranging between 0 C and 100 C, concluding that crack initiation and propagation was slightly slower for this temperature profile. Cracks continued to propagate as a function of temperature cycles. The reason for this difference in crack initiation and propagation was also analyzed.