Optima design of contact opening for relieving current crowding effect in flip-chip solder joints

Abstract

The simulation results show that larger contact opening may not benefit on relieving current crowding effect in the flip-chip solder joints. For the solder joints with a 10-/lm thick Cu UBM, the diameter of the contact opening for the lowest current crowding effect is 60 /lm. It means that using larger or smaller diameter will increase the current density in the solder bumps. In addition, the optima diameter of the contact opening with a thin-film UBM is larger than that with a thick UBM. In this letter, the optimal design rule of contact opening for relieving current crowding effect in solder joints will be provided.

Investigation of novel solder patterns for power delivery and heat removal support

“…It can be improved by the use of advanced under bump metallizations (UBM), resulting in intermetallic compound (IMC) formation with increased EM resistance [ 9]. In addition, Copper pedestals are proposed to mitigate current crowding in the IMC and solder compound [ 10].…”