Thermal and Bonding Strength Evaluation of Die Attach Materials for Power Module Packaging

Die bonding materials are critical in power module packaging, as their ability to withstand the high temperatures generated during device operation directly impacts performance and longevity in real-world applications. Pressure-less soldering and sintering techniques are often preferred due to their simplified processes and lower equipment requirements. However, pressure-less sintering can result in suboptimal bonding strength between the semiconductor die and the Direct Bonded Copper (DBC) substrate, limiting its effectiveness in harsh environmental conditions. This paper investigates the influence of different die attachment materials and methods on power module packaging. Finite Element Analysis (FEA) models are used to analyze the thermal resistances of the die attachment materials. Shear tests were conducted to compare the bonding strength of various materials, including conventional solder preforms (Pb95Sn5), gold-tin alloy (Au80Sn20), silver paste (pressure and pressure-less processes), and silver preforms. Results from the shear tests indicate that pressure-assisted fabrication processes offer the highest bonding strength.