Effect of Junction Temperature Swing (△Tj)
Duration on Lifetime of IGBT Module
Uimin Choi
uch@et.aau.dk
Supervisor
Frede Blaabjerg
Center of Reliable
Power Electronics
Center of Reliable Power Electronics
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Power electronic systems
< General structure of power electronic systems connected to a source and load >
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Power electronic systems play an important role in a wide range of applications in order
to achieve high efficiency and also achieve high performance of the systems
Power electronic systems consist of various components
Each component is closely related to the reliability of overall power electronic systems
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Field Experience in reliability of power electronics
components
< Critical stressor for different components [2] >
< Failure causes in power electronic systems [1] >
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Power devices are one of the reliability-critical components in power electronic systems
Temperature stresses greatly influence a failure of power devices
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Objective
 Lifetime Modeling of IGBT module
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Temperature stress parameters - △Tj, Tjmean, t△Tj
Impacts of junction temperature swing (△Tj) and mean temperature (Tjmean) are
well investigated
Still lack of quantitative study on the impact of temperature swing duration (t△Tj )
Developing lifetime model under realistic electrical conditions including the
temperature swing duration impact
Effect of Tjmean on lifetime of IGBT module
Ncycle  f (ΔTj )  f (Tjmean )  f (tΔTj )
Effect of △Tj on lifetime of IGBT module
Effect of t△Tj on lifetime of IGBT module
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Advanced accelerated power cycling test setup
< Configuration of advanced accelerated power cycling test setup >
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< Prototype of the advanced accelerated power cycling test setup >
Emulate electrical operating conditions of real applications as similar as possible
Apply various thermal stresses conditions easily in a short period by changing the
various parameters - test results can be obtained in a reasonable test time
Real-time measurements of on-state VCE and VF with mV resolution
I-V Characterization of power devices
Low power losses during the power cycling test – cost effective solution
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Power IGBT module under test
< Vertical structure of transfer molded Intelligent Power IGBT
Module >
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< Geometry of transfer molded Intelligent Power IGBT
Module >
Rated power : 600 V, 30 A
6 IGBTs and 6 diodes (3-phases) with embedded gate driver circuits
Covered by epoxy instead of gel
No base plate – failures occurs in bond wires and chip solder
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Power cycling test conditions
< Temperature profiles measured by Infra-Red camera >
Condition
fout
(Hz)
fSW
(kHz)
VDC
(V)
I (A)
Vref
(V)
TH
(˚C)
△Tj
1
0. 1
10
400
21
113
2
0.2
10
400
22
3
0.5
10
400
4
1.0
10
5
1.25
6
1.7
(˚C)
Tjmean
(˚C)
Time
(hours)
Left
samples
59
80.8
102.3
380
0
Finished
115
57
80.6
102.5
230
0
Finished
25
145
53
82.0
101.3
105
0
Finished
400
30
140
48
81.6
102.0
58
0
Finished
12
400
30
140
50
81.8
102.4
55
3
Under test
15
400
30
144
47
80.8
101.0
43
0
Finished
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Power cycling test resutls
 One of power cycling test results
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5 % of VCE_ON increase with respect to its initial value is chosen as the end-of-life
criteria
0.1 Hz
0.2 Hz
0.5 Hz
1.0 Hz
1.25 Hz
1.7 Hz
Cycles
128900
162200
182300
190500
202800
230500
Failure
position
Low side
IGBT of leg A
Low side
IGBT of leg B
Low side
IGBT of leg A
Low side
IGBT of leg B
Low side
IGBT of leg B
Low side
IGBT of leg C
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Lifetime modeling
 Model based on one of the power cycling results
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Weibull analysis is not performed yet – will be applied after all tests are finished
Lifetime models with different definition can be developed – BX, MTTF
0.1 Hz
(5.6s)
0.2 Hz
(3.1 s)
0.5 Hz
(2 s)
1.0 Hz
(1 s)
1.25 Hz
(0.8 s)
1.7 Hz
(0 5882 s)
Nmeasure
128900
162200
182300
190500
202800
230500
Nmodel
136000
155200
171200
199700
209900
224900
N measure  N mod el
 100%
N mod el
-5.22 %
+4.51 %
+6.48 %
-4.61 %
- 3.38 %
+ 2.49 %
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Numerical analysis
 Degradation of a solder joint or a bond-wire
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may be able to be modeled by a uni-axial bimetallic approximation of the thermo-mechanical
stress/strain [3, 4]
(1)
 Three mechanical behaviors under a cyclic strain condition
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Solution of eq.(2) with (1) for a temperature cycle can be represented as a stress-strain
hysteresis loop
The loop area represents the deformation work (△W) or deformation energy
(2)
[
< Stress-strain curves for a thermal cycle [5] >
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Numerical analysis
 Hysteresis stress-strain curves
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SnAg3.5 Solder, Al2O3 DCB are considered for case study
< Parameters for SnAg3.5 [6] >
< Stress-strain curves of solder joint under the six different conditions>
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As the output frequency decreases, the stress-strain curve area increases
longer t△Tj has the larger deformation work (△W) during the temperature cycle
- cause the different number of cycles to failure
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Physics-of-failure analysis
 Operating condition 4 (1 Hz)
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Test was stopped at 10 – 15 % increases from its initial value
The bond-wire cracks are observed in all 5 bond wires
No degradation in diode
< Low side IGBT of phase-V>
< Low side diode of phase-V>
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Physics-of-failure analysis
 Operating condition 4 (1 Hz)
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(a) Reference module - Brand new
(b) tested module - after test
No degradations in solder joint
No fracture in Al – Si interface
Black spot in the solder joint
- from diamond lapping film
< Low side diode of phase-V>
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Physics-of-failure analysis
 Operating condition 1 (0.1 Hz)
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The bond-wire cracks are also observed in bond wires under condition 4
(a) Reference module – Brand new
(b) tested module – Condition 4
(c) tested module – Condition 1
No degradations in solder joint
Fracture in Al - Si interface
under the condition 1
< Low side diode of phase-V>
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Conclusion
 Effect of Junction temperature swing duration (t△Tj) on lifetime of IGBT
module has been investigated
 As duration increases, the number of cycle to failure decreases
 Bond-wire crack is the main failure mechanism under the tested conditions
 Statistical analysis will be considered
 Lifetime model including t△Tj effect can be developed
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Reference
[1]
[2]
[3]
[4]
[5]
[6]
S. Yang, A. Bryant, P. Mawby, D. Xiang, R. Li, and P. Tavner, “An Industry-Based Survey of Reliability in Power Electronics
Converters,” IEEE Transactions on Industry Applications, vol. 47, pp. 1441-1451, May/June 2011.
H. Wang, M. Liserre, F. Blaabjerg P. de Place Rimmen, J. B. Jacobsen, T. Kvisgaard, and J. Landkildehus, “Transitioning to Physics-ofFailure as a Reliability Driver in Power Electronics,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 2, no. 1,
pp. 97-114. Mar. 2014
M. Ciappa, and A. Blascovich, “Reliability odometer for real-time and in situ lifetime measurement of power devices,”
Microelectronics Reliability, vol. 55, no.9-10, pp. 1351-1356, Aug.-Sep. 2015.
C. H. Raeder, L. E. Felton, R. W. Messler, JR, and L. F. Coffin, Jr., “Thermomechanical Stress-Strain Hysteresis of Sn-Bi Eutectic Solder
Alloy,” in Conf. Rec. IEMT 1995, pp. 263-268, 1995.
P. Hall, “Creep and Stress Relaxation in Solder Joints of Surface-Mounted Chip Carriers,” IEEE Transactions on Components,
Hybrids, and Manufacturing Technology, vol. CHMT-12, no. 4, pp. 556-565, Dec. 1987.
R. Darveaux, and K. Banerji, “Constitutive Relations for Tin-Based Solder Joints,” IEEE Transactions on Components, Hybrids, and
Manufacturing Technology, vol. 15, no. 6, pp. 1013-1024, Dec. 1992.
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CORPE
www.corpe.et.aau.dk
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