Gold-Gold Interconnects to Copper Pillar using fast Thermal Compression Bonding using Non-conductive paste

Abstract

Flip chip bonding requires a device to be flipped and attached to the bond pads or traces on the substrate. For lower pitch devices with large bond pads, this was accomplished using gravity reflow followed by capillary underfill (CUF). For fine-pitch devices mounted close to each other on a substrate, CUF has not been as effective as the use of a Non-conductive paste (NCP) during Thermal Compression Bonding (TCB). The NCP provides reliability during post bonding testing and ensures a strong die to substrate bonding. The authors will describe the formulation of a new NCP that provides fast, reliable bonding for Copper Pillar and Gold Gold bonding.