Thermal fatigue life prediction of Ag-2.5Sn solder joint in flip chip

Abstract

The heat dissipation needs of high-power devices cannot now be met by traditional packing solders due to the fast development of microelectronics interconnect technology. In addition to having outstanding thermal and electrical conductivity, nano-silver-tin paste better satisfies the needs of electronic devices. Studying the thermal reliability of solder joints is extremely important, this article investigates the fatigue life of the nano-silver-tin solder joints in temperature cycling experiments. Based on the life test results, the thermal cycling fatigue life of the nano-silver-tin solder joint is determined to be 2880 cycles. Finite element software was used to replicate the chip’s bonding process and assess the solder joint stress and strain distribution. The stress and strain of nano-silver-tin solder connections under thermal cycling load are accurately modeled using the Anand viscoplastic model and elastic model. The findings indicate that the contact region between the solder connections and copper columns is where the chip generates the most stress and strain. The fatigue life of the solder joint is estimated by using the Coffin–Manson modified equation, and this prediction aligns closely with the experimental results.