Nanotechnologies / Materials
Power devices, EV/HEV cars, Drones, Aerospace, 5G/6G communication

Detecting early-stage failure by AE monitoring in WBG
electric power conversion devices
Laboratory of flexible and power three dimensional system integration, The Institute of Scientific and Industrial Research (SANKEN)SA Associate Professor Chuantong Chen

Researchmap https://researchmap.jp/chenchuantong

SA Professor Katsuaki Suganuma

Researchmap https://researchmap.jp/ksuganuma

Nanotechnologies / Materials

Abstract
In the article, acoustic emission (AE) was applied to monitor thewear-out failure in discrete SiC Schottky barrier diodes devices witha Ag sinter die attach to successfully monitor the real-time progressof failure of Al ribbons for the first time. AE signals were successfully collected for the SiC devices during a power cycling test. AE
counts that correspond to one of the time-domain parameters of
AE signals increased with power cycling, thereby corresponding tothe observed fatigue cracks in Al ribbons leading to lift-off failure.
Based on the relationship between an AE count rate and fatigue
crack growth rate, the results indicate that AE monitoring can beused to understand the fatigue propagation in Al ribbons (i.e., failure mechanism) and also as an early warning before catastrophic
lift-off fracture for power electronic devices.

▍Background & Results

The emergence of power electronic devices using silicon carbide(SiC) semiconductors has facilitated more compact designs andhigh energy efficiency due to its superior material properties . However, compared to traditional silicon (Si), the raised energy densityof SiC-based power electronic devices requires high-temperature
operation and results in many reliability issues. In SiC-based power electronic devices, wear-out failure after long-term operation ismainly caused by the failure in packaging components, such as
bond wire lift-off, substrate delamination, and die attach cracks.
However, the current failure precursor monitoring such as ON-state
resistance, collector–emitter voltage, forward voltage, is limited for
application in power electronic devices. In this article, AE was applied for the first time to real-time monitoring of wear-out failure of
discrete SiC Schottky barrier diode (SiC-SBD) devices during PCT.
The collection of AE signals during PCT and relationship between
the observed damage and acquired AE signals is presented.
A number of AE signals were successfully detected during PCTprior to reaching final failure. The source of AE signals is attributed
to the initiation and propagation of fatigue cracks in Al ribbons.
This demonstrates that AE monitoring exhibits excellent sensitivity
to fatigue cracks. The AE acquisition can be used as a sensitive
early warning method via detecting fatigue cracks that lead to catastrophic lift-off failure in the ribbons.

Al ribbons

Die boding

以上以上

Resin

SiC
Cu Substrate
Ceramic
Cu Substrate

SiC SBD

Al ribbons

Al ribbons

SiC SBDSiC SBD

Sintered AgCracks➢No crack initiated in the sintered Ag layer.

➢Crack mainly happened at the ribbon-chip bonding interface.

➢Vf increases and AE signals are ascribed to the ribbon lift-off.

Cu Substrate

Fig.1 The cross-section of SiC power module and the crack extension and deterioration at the wire joint interface during the power cycling test

Fig.2 Deterioration detection technology by AE(Acoustic-Emission) sensor in thepower module wires caused by the thermal fatigue▍ Significance of the research and Future perspective
This study used acoustic emission during power cycling tests tomonitor in real time the complete failure process—from the earliest
stages—in silicon carbide Schottsky diodes. This development
will help solve wear-out failure problems that are limiting advanced
applications in computers, solar cells, and many other devices.
Future studies will focus on development of AE monitoring systemusing the packaged piezoelectric element inside power module toensure reproducibility and price competitiveness.

P a t e n t
Choe, C; Chen, C; Nagao, S et. al. Real-time acoustic emission monitoring of wear-out failure in SiC power electronic devices during power cycling tests.
IEEE Transactions on Power Electronics. 2021; 36 (4): 4420-4428. doi: 10.1109/TPEL.2020.3024986.
UR
L https://resou.osaka-u.ac.jp/en/research/2020/20201015_1
K e y w o r d power electronics, AE sensing, failure diagnosis, Ag sinter joining
Tr e a t i s e1