High Thermal Durability of Thin Copper Die-attach Layers and Finite Element Model Simulation

Abstract:
A thin but highly durable bonding layer is strongly desired for cost reduction and improving reliability in power device market. Dense Cu bonding layers having a thickness of 15 µm provided high thermal stability for a thermal cycle test (TCT) operated in 4000 cycles at between –55 and 200 °C under air, because was no significant delamination and no changed microstructure. Microstructure of the sintered Cu layers was homogenous and the porosities were 4.8%, originating in high dispersibility of the submi-cron Cu particles. The thermal reliability of the dense sintered Cu layers was subjected to the Coffin-Manson law, which the plastic strain amplitude calculated by a finite element model simulation was proportional to the number of cycles to failure (cycles of delamination ratio 10% over during TCT). The results can be of assistance to predict the life of the dense sintered Cu bonding layers being operated in power devices.