Effects of alternating thermal stress on delamination between die attach and leadframe in SOIC package

Delamination was a critical failure to the microelectronics products, and it was introduced mainly by two factors: strong interface stress or poor interface adhesion. In this paper a tracking experiment confirmed the delamination between die attach and leadframe flag in a SOIC device, which occurred during wire bonding. Results of actual experiments and FEA found during the process flow, there were changes of structure profile as well as von Mises stress at the edge of die attach layer. This alternating stress was introduced by temperature cycling during D/A curing, wire bonding and following cooling; and resulted into the delamination at the interface, whose occurrence could be reduced when a higher peak temperature of D/A curing, a lower temperature of wire bonding, a thicker BLT or a CTE-lower die attach was applied. With a balance between delamination and other items, a final solution was proposed and got perfect results.