Flip-chip packaging process utilizing no-flow underfill technique

摘要

A flip-chip packaging process is proposed, which can help assure reliable electrical bonding between chip-side solder bumps and substrate-side bond pads without being made open-circuited by the electrically-insulative material being used for flip chip underfill. The proposed flip-chip packaging process is of the type utilizing a no-flow underfill technique to prevent short-circuiting between neighboring solder bumps, and is characterized in the fabrication of electrically-conductive sharp-pointed studs over substrate-side bond pads to prevent open-circuiting between chip-side solder bumps and substrate-side bond pads. These electrically-conductive sharp-pointed studs can pierce into the chip-side solder bumps when mounting the flip chip onto the substrate, so that during subsequent solder-reflow process, the piercing of these sharp-pointed studs in the solder bumps can help allow the solder bumps to be reliably wetted to the substrate-side bond pads, thereby establishing reliable electrical bonding between the chip-side solder bumps and the substrate-side bond pads. The finished flip-chip device is therefore more assured in quality and reliability.