Effect of Pd distribution on Pd-plated Cu wire using different electronic flame off settings

Abstract

Pd-coated Cu wires show interesting properties such as good electrical conductivity, thermal conductivity, and reliability and are widely used in microelectronic packaging. However, during the formation of free air balls (FABs) and bonded balls via Pd-coated Cu wires, the electronic flame off (EFO) current setting affects Pd distribution in FABs and bonded balls. This study investigated the effect of different EFO current settings on Pd distribution during the formation of FABs and bonded balls, and also analyzed the influence of EFO current settings on FAB formation. Pd distribution in FABs and bonded balls, as well as the distribution of other elements, were observed. The corrosion on the surface of a bonded ball was observed through high temperature storage tests (HTSTs). The result revealed that there were different Pd distributions in the formation processed via different EFO current settings of FABs and bonded balls. Further, different EFO current settings also resulted in a different FAB shape. The result of HTST indicated that proportional Pd distribution could decelerate the corrosion of a bonded ball.