Reliability of sintered Ag80–Al20 die attach nanopaste for high temperature applications on SiC power devices

The aim of this research work is to present a reliability analysis on the suitability of the Ag80–Al20 sintered die attach nanopaste for high temperature applications on SiC power devices. Die back metallization studies pointed out that Ag and Au would be suitable candidates to form a strong bond between the SiC die and Ag80–Al20 die attach for high temperature operations. The post-sintered Ag80–Al20 die attach revealed a low modulus of elasticity at 9.8 GPa due to the formation of micro-pores during sintering. This also influenced the hardness and stiffness as well at 0.49 GPa and 30354.14 N/m, respectively. The electrical conductivity of the Ag80–Al20 die attach material decreased slightly with increasing thermal aging repetitions. As the die attach material aged, it seemed to undergo a reduction in electrical performance, though as shown earlier the structure was still intact. This decomposition was suggested to occur due to the organic–metallic system’s composition itself, and the volatility of the residue organics.

► Ag80–Al20 nanopaste sintered at 380 °C melts at 585 ± 1 °C and operates at 302–457 °C. ► Post-sintered nanopaste density was 61.1% that of bulk Ag. ► Thermal and electrical conductivity was 1.005 × 105 (Ω cm)−1 and 123 W/m K. ► Low CTE value of 7.74 × 10−6/°C is close to that of SiC. ► Formation of pores during sintering helped reduce E modulus, H and S values.