Thermomechanical and fatigue analysis of SiC power modules with a comparison of sintered silver and copper die attaches

Tools

Liang, Shuibao and Guo, Zhihao and Jiang, Han and Zhong, Zhihong and Xu, Yaohua and Wang, Yi and Ramachandran, Saran (2025) Thermomechanical and fatigue analysis of SiC power modules with a comparison of sintered silver and copper die attaches. Journal of Electronic Materials. ISSN 0361-5235 (https://doi.org/10.1007/s11664-025-12513-2)

[thumbnail of Liang-etal-JEMS-2025-Thermomechanical-and-fatigue-analysis-of-SiC-power-modules]
Preview
 Text. Filename: Liang-etal-JEMS-2025-Thermomechanical-and-fatigue-analysis-of-SiC-power-modules.pdf
Accepted Author Manuscript
License: Creative Commons Attribution 4.0 logo
Download (1MB)| Preview

Abstract

Sintered silver is widely used for reliable interconnects in silicon carbide (SiC) power module packaging but is limited by high cost and significant ionic migration issues. Sintered copper offers a promising, cost-effective alternative. Despite its potential, comparative studies on the mechanisms behind the high reliability of sintered copper remain limited. This work develops finite element models of SiC power modules with sintered silver and sintered copper die attaches for comparative thermomechanical analysis and fatigue lifetime prediction, where the viscoplastic behavior is represented using the Anand model and fatigue lifetime is predicted based on the Engelmaier model. The results show significant stress concentration at the die attach interfacial corners near the substrates, with higher stresses in the sintered copper layer and larger equivalent viscoplastic strain in the sintered silver layer. The viscoplastic dissipation energy density in both die attach layers concentrates at the interfacial corners near the directionally bonded copper substrate, where fatigue cracks are more likely to initiate. Cracks initiate earlier in the sintered silver layer than in the sintered copper layer. Although the sintered copper layer experiences higher thermal stress, the higher yield strength of sintered copper and the lower coefficient of thermal expansion (CTE) mismatches between the sintered copper and the copper substrate result in less viscoplastic strain accumulation in the sintered copper layer, leading to less fatigue damage in the sintered copper layer than in the sintered silver. The fatigue lifetime of SiC power modules with sintered copper die attach is significantly longer than that with sintered silver, and the simulation results align with experimental observations.

ORCID iDs

Liang, Shuibao, Guo, Zhihao, Jiang, Han, Zhong, Zhihong, Xu, Yaohua, Wang, Yi and Ramachandran, Saran ORCID logoORCID: https://orcid.org/0000-0002-6881-2940;
CORE (COnnecting REpositories)