Reliability Assessment of Flip-chip Assembly of Al Bumps

This paper reports on a flip-chip bonding technology using an aluminum bump at high temperatures, such as for SiC semiconductors. In recent years, double-sided mounting structures have been proposed for the purposes of miniaturization and low inductance. The surface mounting method requires durability to withstand high temperatures. We propose a new technique for the flip-chip bonding of an Al bump made from bonding wire. The recrystallization temperature of aluminum is under 250 °C. As a result, there is an expectation of mitigating mechanical stress between the chip and bonded substrate. A high-temperature exposure test at 250 °C for 3000 hours and a thermal-cycle test between −40 and 250 °C for 3000 cycles have been executed. Results indicate that shear strength of the Al bump meets the requirements set forth in the IEC60749-19 guideline until 2000 cycles at room temperature.