Increasing the reliability of aluminum wirebonds by thermal treatments: analysis and implementation

In this work we studied the effect of a post-bonding thermal treatment on thick aluminum wirebonds lifetime in IGBT power modules during power cycling at different temperature swings. A reliability improvement of up to 44% is demonstrated for the bonds located at the center of the chip and seeing th...

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Bibliographic Details
Published in:IEEE journal of emerging and selected topics in power electronics 2023-06, Vol.11 (3), p.1-1
Main Authors: Pichon, Pierre-Yves, Brandelero, Julio, Lelesle, Johan, Ouhab, Merouane, Quemener, Vincent
Format: Article
Language:English
Subjects:
Aluminum
Crack propagation
Electrothermal modelling
Gate Driver
Heat treatment
Insulated gate bipolar transistors
Mechanical factors
Metallization
Microstructure
Nanoindentation
Physics of Failure
Recrystallization
Reliability
Reliability Analysis
Semiconductor devices
Temperature Control
Temperature measurement
Wirebonds
Wires
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Summary:In this work we studied the effect of a post-bonding thermal treatment on thick aluminum wirebonds lifetime in IGBT power modules during power cycling at different temperature swings. A reliability improvement of up to 44% is demonstrated for the bonds located at the center of the chip and seeing the highest thermal treatment temperature. The physical phenomena occurring during the thermal treatments and during power cycling are studied using microstructure analysis (Scanning Electron Microscopy techniques) and nanoindentation. Softening of the material results from recrystallization and/or recovery during thermal treatment, whereas during power cycling the thermal treated material hardens due to strain accumulation and defect formation. Despite the hardening our data suggests a decrease in crack growth rate at the second half of the testing time. We implemented an approach for applying thermal treatments during typical operating conditions in a converter by controlling the off-state losses of a device in a multichip configuration. The stability and the limits of this approach are studied experimentally and described by an electrothermal model. This study allows us to conclude on a realistic process window for online thermal treatments, by considering both material constrains and practical temperature control limits.
ISSN:2168-6777
2168-6785
DOI:10.1109/JESTPE.2022.3231963