Aging failure analysis of multi‑discrete parallel modules based on new separation method of thermal resistance

Dingyi Wang; Xing Zhang; Shaolin Yu; Zhaoyang Wei

Aging failure analysis of multi‑discrete parallel modules based on new separation method of thermal resistance

Vol. 26, No. 3, pp. 696-708, Mar. 2026

10.1007/s43236-025-01104-3

System module

Power cycling

Structure function method

Thermal resistance measurement

Failure mechanism

Abstract

Currently, most power cycling tests focus on studying the power device itself. However, in actual electric vehicle inverters, connection layers are present between the power device and the heatsink, such as thermally conductive silicone grease. In addition to the internal packaging materials of the power device, aging of the external connection layer can also lead to an increase in thermal resistance, which can accelerate the aging of the power device. As a result, simply evaluating the internal packaging reliability of the power device does not adequately reflect the actual failure mode and lifespan. In the existing studies, it is challenging to independently monitor the thermal resistance of each physical layer in system modules with multi-layered structures. This study takes a multi-discrete parallel system module in an electric vehicle inverter as an example and proposes a new method for separating and extracting the thermal resistance of physical layers. This enables the monitoring of changes in both the internal junction-to-case thermal resistance of the power device and the thermal resistance of the external thermally conductive silicone grease in the system module. Results show that the increase in thermal resistance caused by the positional shift of silicone grease is the primary cause of accelerated failure of the system module at high temperatures. Finally, a failure mechanism analysis was conducted through junction temperature simulations, and the accuracies of the proposed thermal resistance separation method and failure analysis were verified experimentally. This study provides technical support for enhancing the reliability of system-level module devices.

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Cite this article

[IEEE Style]

D. Wang, X. Zhang, S. Yu, Z. Wei, "Aging failure analysis of multi‑discrete parallel modules based on new separation method of thermal resistance," Journal of Power Electronics, vol. 26, no. 3, pp. 696-708, 2026. DOI: 10.1007/s43236-025-01104-3.

[ACM Style]

Dingyi Wang, Xing Zhang, Shaolin Yu, and Zhaoyang Wei. 2026. Aging failure analysis of multi‑discrete parallel modules based on new separation method of thermal resistance. Journal of Power Electronics, 26, 3, (2026), 696-708. DOI: 10.1007/s43236-025-01104-3.