thermal mechanical reliability of igbt power electronics

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Institute of Electronic Packaging Technology and ReliabilityBeijing University of Technology

Tong An Ph.D./Associate Professor

Thermal Mechanical Reliability of IGBT Power Electronics Packaging

Outline

1. Introduction

2. Tested IGBT Modules and Power Cycling Test Bench

3. Effect of Microstructure Evolution of the Aluminum Metallization Layer

4. Thermal and Mechanical Analyses of IGBT Modules

5. A Lifetime Prediction Method of IGBT Modules

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Outline

1. Introduction





1. Introduction

Institute of Electronic Packaging Technology and Reliability was founded in 2006. By October 2020, it

has 7 full-time teaching staff, 31 postgraduate students (including 6 doctoral students and 25 master students).

By the end of 2019, we obtained 8 projects of National Natural Science Foundation of China, 4 branch project

of National Science and Technology Major Project of the Ministry of Science and Technology of

China, 1 branch project of National Key R&D Program of China, more than 20 entrusted projects by

enterprises. We have published more than 160 articles, have more than 60 patents.

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Outline

1. Introduction






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New Energy Generation Systems

Locomotive Tractions

AerospaceNew Energy Generation Systems

Locomotive Tractions

Aerospace

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1200 V/450 A IGBT module

Cross-section schematic of the IGBT module 7

IGBTIGBT DiodeDiode

CeramicCeramic

Heat sinkHeat sink

Al metallizationAl metallization

Thermal grease

Thermal grease

Al bond wireAl bond wire

Chip solderChip solder

CopperCopper

Base solerBase soler

Base plateBase plate

IGBT Diode

Ceramic

Heat sink

Al metallization

Thermal grease

Al bond wire

Chip solder

Copper

Base soler

Base plate

Al, 23.5Si, 2.6SnAgCu, 12~23Cu, 17.5Al2O3, 6.8 or AlN, 4.7AlSiC, 7.5


CTE: 1×10-6/℃CTE: 1×10-6/℃


CTE: 1×10-6/℃

Data acquisitionsystem


PowersupplyPowersupply

Drivingandprotectsystem


Water cooling heat dissipation deviceWater cooling heat dissipation device

DUTDUT

DUTDUTDrive circuitDrive circuit


Powersupply


Water cooling heat dissipation device

DUT

DUTDrive circuit


Prototype of the test setup 8

Configuration of the DC power cycling test

Configuration of the PWM power cycling test

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Outline

1. Introduction






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Control signal and junction temperature profile

Pico Scan TM 2500 Atomic Force Microscope


3D surface morphology3D surface morphology

RTS-9 Dual Electrical Measuring Four Probe Tester


Resistance testResistance test

Test positionsTest positions

Surface morphologySurface morphology

Quanta 650 Scanning Electron Microscope


Cross section imageCross section image

Helios Nanolab 650 Double Beam Scanning Electron Microscopy


P1 P2 P3P1 P2 P3

P1: the central area of the chipP2: the area near the bond wire heelP3: the area at the edge of the chip


I

v


3D surface morphology


Resistance test

Test positions

Surface morphology


Cross section image


P1 P2 P3


Scanning electron microscopy (SEM)Atomic force microscopy (AFM) Four-point probe testerFocused ion beam (FIB)

Surface morphologyRoughnessResistanceCross-section observation

A. Al metallization layer testing procedure

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(a) 0 kcycles Module A0%-I(a) 0 kcycles Module A0%-I (b) 100 kcycles Module B50%-I(b) 100 kcycles Module B50%-I

(c) 164 kcycles Module C85%-I(c) 164 kcycles Module C85%-I (d) 193 kcycles Module D100%-I(d) 193 kcycles Module D100%-I

(a) 0 kcycles Module A0%-I (b) 100 kcycles Module B50%-I

(c) 164 kcycles Module C85%-I (d) 193 kcycles Module D100%-I

20 μm 20 μm

20 μm 20 μm

Regularstructure

Increasingroughness

Significantlyconstruction

Extrusionappear

0 kcycles

100 kcycles

164 kcycles

193 kcycles

Surface degradationSurface degradation


B. SEM images of the Al metallization layer

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(a) 0 kcycles Module A0%-I (b) 100 kcycles Module B50%-I

(c) 164 kcycles Module C85%-I (d) 193 kcycles Module D100%-I

5 μm5 μm

5 μm 5 μm

Intact

Intergranularcracks

Crackspropagation

Presentgrooves

0 kcycles

100 kcycles

164 kcycles

193 kcycles

Substantial degradation


C. Cross-section observations

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(a) 0 kcycles Module A0%-I(a) 0 kcycles Module A0%-I (b) 100 kcycles Module B50%-I(b) 100 kcycles Module B50%-I (c) 164 kcycles Module C85%-I(c) 164 kcycles Module C85%-I (d) 193 kcycles Module D100%-I(d) 193 kcycles Module D100%-I

AFM images of the Al metallization layerAFM images of the Al metallization layer

(a) 0 kcycles Module A0%-I (b) 100 kcycles Module B50%-I (c) 164 kcycles Module C85%-I (d) 193 kcycles Module D100%-I

0

0.3

0.6

0.9

1.2

1.5

1.8

μm

0

0.5

1

1.5

2.5

3.5

4

μm

2

3

0

0.5

1

1.5

2.5

3.5

4

μm

2

3

0

0.5

1

1.5

2.5

3.5

4

μm

2

3

AFM images of the Al metallization layer

Hei

ght p

rofil

es(μ

m)

Hei

ght p

rofil

es(μ

m)

x or y (μm)x or y (μm)

λiλi BaselineBaseline

x or yx or y

AlAl

zizi

Path 3Path 3

zizi

Path 4Path 4

Path 4Path 4

Path 3Path 3

Path 1Path 1

Path 2Path 2

zz

zz

xx

yy

Path 2Path 2

Path 1Path 1

Definition of the surface roughness of the Al metallization layerDefinition of the surface roughness of the Al metallization layer

0 10

20

30

40

μm

0 10 20 30 40μm

4.5

4

3.5

3

2.5

2

1.5

1

0.5

0 0 5 10 15 20 25 30 35 40

1.00.50.0

-0.5-1.00.50.0

-0.5-1.00.50.0

-0.5-1.00.50.0

-0.5-1.0

Hei

ght p

rofil

es(μ

m)

x or y (μm)

λi Baseline

x or y

Al

zi

Path 3

zi

Path 4

Path 4

Path 3

Path 1

Path 2

z

z

x

y

Path 2

Path 1

Definition of the surface roughness of the Al metallization layer

a

1, d d

A

S

z x y x yA

Arithmetical mean roughness

2q

1

1 N

ii

R zN

ave1

1 N

iiN

Root mean square roughness

Average distance between two neighboring asperities


D. Surface roughness evolution of the Al metallization layer

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Relationship between the electrical resistance and the morphology parameters of the Al metallization layer

Surface roughness distribution of the Al metallization layer during the power cycling process

The distribution of resistance variation in the Al metallization layer


E. Effect of the Al metallization layer surface morphology on its electrical resistance

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Relationship between the electrical resistance and the morphology parameters of the Al metallization

layer

Finite element model of the Al metallization layer

Model No.

Model I Model II Model III Model IV Model V Model VI Model VII Model VIII

Rq (μm) 0.1 0.3 0.5 0.7 0.6 0.6 0.6 0.6

λave (μm) 4.0 4.0 4.0 4.0 4.0 5.0 6.0 7.0

Resistance (mΩ)

6.926 7.543 8.426 9.013 8.925 8.016 7.542 6.984

Morphology parameters and the results of the FEA


E. Effect of the Al metallization layer surface morphology on its electrical resistance

Outline

1. Introduction





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Condition Waveform of the loading currentDC

current (A)fsw (Hz) δ ton (s) toff (s)

DC-1 140 0.125 0.5 4 4

DC-2 140 20 0.5 0.025 0.025

DC-3 140 5 k 0.5 1×10-4 1×10-4

(fsw: Switching frequency, fop: Operation frequency, δ: Duty cycle, ton: Power-on duration,toff: Power-off duration)

Condition Waveform of the loading currentMax/RMS current (A)

fsw (Hz) fop (Hz) ton (s) toff (s)

PWM-1 200/140 10 k 40 4 4

PWM-2 200/140 5 k 40 0.025 0.025

PWM-3 200/140 10 k 40 0.025 0.025

Test conditions of DC power cycling tests

Test conditions of PWM power cycling tests

Multiple time-delayed acquisition method

A. Test conditions of power cycling tests

Prototype of the test setup


18PWM-I test conditionDC-I test condition

DC-I test condition

PWM-I test condition

Temperature distributions of the IGBT chip at t = 3.895 s

B. Evolution of temperature in the IGBT chip over time

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C. Electrical-thermal-mechanical finite element analysis

Comparison of temperature distribution of the IGBT module at the power-off moment under the

DC-I test condition

Comparison of S11 stress under different test conditions

3D FE model of the IGBT module

Outline

1. Introduction





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Start Cycle numberi=1

Simulation timets=0

Power loss model

con ce0_25 C V j c

2ce_25 C r j c

= + 25 C

+ 25 C

P V K T I

r K T I

Electrothermal model

ts=ts+ts

ts=tcycle_i

Degradation model of rce

0

0 j0 0

B javg

0 ,

exp ,n

D t t

Q a TD C t t t t

K T

Increment of rce

1ce_25 C

1

di

i

N t

ti

r D t

rce_25℃≥8%rce0_25℃

rce_25℃=rce0_25℃+rce_25℃

i=i+1ts=0

Tjavg & Tj calculation

Accumulated Eloss

jmax jminjavg

j jmax jmin

=2

=

T TT

T T T

1

loss loss,1

cycle_1

di

i

N t

iti

N

ii

E P t t

t t

Number of cycles to failure

Nf =iEnd

Yes

Yes

No

No

Input parametersIc ,, Tj0

Water temperatureTw


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Electrothermal ModelElectrothermal Model Degradation Model of rCEDegradation Model of rCEElectrothermal Model Degradation Model of rCE

The lifetime prediction of IGBT module implemented in Matlab/Simulink

DC PC test condition Tjavg (℃) Tj (℃)Nf (cycles) Relative

errorPredicted lifetime

Test result

AIload=400A, Tw=45℃, ton/toff=2s/2s

98.0 69.0 183,811 165,000 11.4%

BIload=400A, Tw=45℃,ton/toff=4s/4s

98.3 78.5 50,760 37,500 35.4%

CIload=400A, Tw=45℃,ton/toff=6s/6s

98.5 84.8 25,754 17,500 47.2%

DIload=400A, Tw=55℃,ton/toff=2s/2s

107.8 69.6 129,272 ‐‐ ‐‐

EIload=400A, Tw=65℃,ton/toff=2s/2s

118.4 70.4 98,262 ‐‐ ‐‐

DC PC test conditions and predicted lifetimes

Predicted lifetimes obtained by different methods

thermal mechanical reliability of igbt power electronics

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