抄録
In the reflow soldering process, the IC package is heated over 270℃ by the infrared rays. In a delamination interface, the stress field near a crack tip will always be in a mixed-mode state. It was assumed that the initial defects were generated among the corner part of die pad and epoxy molding compound. The 3-D finite element analysis was carried out to evaluate the strain energy release rate (SERR) of delamination interface in IC packages subjected to non-steady thermal stress. SERR of mixed mode was evaluated by the modified crack-closure integral (MCCI) and virtual crack extension method (VCEM). The maximum difference of SERR between MCCI and VCEM was about 8%. Therefore, it is considered that MCCI is useful as the simple evaluation method of SERR. The stress intensity factor K was examined from 3-D VCEM. VCEM can evaluate stress intensity factors of the interface crack under a mixed-mode loading accurately.
