A dry migration? Copper dendrite growth in adhesive tape during burn-in

Copper migration which exhibits dendrite short-circuits in conductor-insulator-conductor structures may result in failure and reliability problems in microcircuits. Earlier works (Harsanyi, 1995; Adema et al., 1990 and 1993; Rudra and Jennings, 1994; Nieman, 1994; Harsanyi, 1999) have shown this mechanism in moist conditions. This is known as wet migration. In this investigation, we have observed copper dendrite growth during burn-in stress in adhesive tape which was used for leadframes to maintain the coplanarity and stability of individual lead pins during semiconductor manufacturing. A special parallel lapping technique revealed the dendrite growth under the tape. It is believed that chemical interaction has taken place, especially due to polyamic acid, which apparently reacts with copper. Further evaluations with higher temperature and voltage simulation confirm this mechanism.