Reliability Benchmarking Novel Ag-sinter Die-Attach Against High-Pb Solder Under Thermal Cycling and High-Temperature Storage Testing

Continued reliance on high-Pb solders for die-attach applications in discrete power semiconductor packaging remains a major challenge in achieving fully Pb-free manufacturing. Although pressureless Ag-sintering emerged as a promising alternative, demonstrating its suitability as a drop-in replacement requires compatibility with high-volume manufacturing processes. In this study, a practical set of processability and reliability requirements was established to evaluate a pressureless pure Ag-sinter material (DA252) formulated by Heraeus as a Pb-free alternative. The DA252 material was assessed on automotive-grade PQFN- packaged Si-MOSFETs and benchmarked against standard high- Pb (Pb92.5Sn5Ag2.5) solder. Processability was assessed through bondline thickness, void content, and die-shear strength, while reliability was investigated through thermal cycling (−55◦C to 150◦C for 2000 cycles) and high-temperature storage (150◦C for 2000 hours) tests. Device health was monitored through changes in on-state resistance (RDS(on)), following AEC-Q101 qualification criteria. The evaluated pressureless Ag-sinter paste exhibited a homogeneous die-attach interface with bondline shrinkage below 25%, average void content below 0.2%, and a die shear strength > 1.5Kg/mm2 (>15MPa) at both RT & 260◦C. During thermal cycling, the Ag-sintered samples maintained a relatively stable electrical performance compared to the benchmarked high-Pb solder, particularly for larger die configurations where thermomechanical stresses were most severe. Stable electrical characteristics were also observed over 2000 hours of high-temperature storage testing. The results presented in this study demonstrate the processability and reliability of pressureless cured pure Ag-sinter DA252 material in cost-sensitive high-volume discrete power semiconductor packaging. Complementary failure analysis and inspection on microstructural evolution are further required to warrant the DA252 material’s robustness.