Innovative Techniques for Thermal Characterization and Inline-Capable

Thermography-Based Failure Analysis

27 June 2019

Tobias von Essen

Origin

» Founded in 2004 as Fraunhofer spin-off

» Continuous refining of expertise from general reliability to focus on thermal management and thermal characterization

» Today partner of major European electronic industries and full-scale provider for thermal characterization and reliability analyses

» Creative, flexible and multidisciplinary team of physicists, mathematicians, programmers and engineers

» Member and co-founder of the Joint Lab Berlin for Technical Safety

Tobias von Essen

27 June 2019

Nanotest in numbers

» 15 years experience

» 20 research projects

» 20 employees

» 2 laboratory sites

Portfolio Overview

Thermal Analysis Services

» Materials & compounds characterization

» System and package analysis

» Failure detection & localization

» Reliability investigation

Thermal Measurement Equipment

» Thermal conductivity & diffusivity

» Solids to liquids

» Material aging investigation

» Measurement & calibration equipment

Research & Development

» Joint and bilateral research projects

» Non-standard measurement tasks

» Novel method deployment

» Customer-specific solutions

» Thermal consulting & training

» Regular publications and tutorials

Tobias von Essen

27 June 2019

Serv

ices

Pro

du

cts

Develo

pm

en

t

Chip #5, 3.2 kJ, pulse length <9,8 ms

http://www.ti.com/lsds/ti/applications/industrial

Motivation

» Reliability in electronics is

less or more important

» Irreliability often more

expensive than reliability

» Thermal performance is

vital to reliability

» Subject to reliability testing:

› Materials

› Systems

› Processes

» Knowledge is key

27 June 2019

Tobias von Essen

Motivation

27 June 2019

Tobias von Essen

Reliable and contextually valid material data is

required

» Evaluation for material development

» Material selection in electronics development

» Input data for simulation

» Datasheets

» Quality assessment

Electronic components and systems contain

» Semiconductors SiC, GaN, Si, different doping

» Metals cooler, heat spreaders, metallization

» Substrates ceramics, polymers, composites

» Die attaches solders, sinter materials, adhesives

» TIMs silicone-based, metal-based, carbon-based

Substrate

Underfill

Cu

Si Cu

Si

TIM1 TIM1

Solder

Our vision: in one minute to thermal conductivity

27 June 2019

Tobias von Essen

Sample

3ω from lab to

industrial level

Results in

< 1 min

Measurement Principle Schematic

Quick Thermal Material Characterization with Minimum Effort

Feasible Samples

» Liquids

» Gels

» Pastes

» Solids

Material Parameters

» Bulk thermal conductivity

» Thermal diffusivity

TOCS® Three Omega Characterization System

27 June 2019

Tobias von Essen

Sample material is simply applied on the test

chip and measured with a mere button press.

Amplitude of temperature oscillation at the sensor vs. electrical frequency

3ω-measurements of TIM materials

27 June 2019

Tobias von Essen

Sarcon SPG-

30A

silicone compd.

Wacker® P12

silicone paste

Dow Corning®

TC-4525 gap

filler

Dow Corning®

340 heat sink

compd.

Thermal conductivity of epoxy during curing

Tobias von Essen

27 June 2019

→ Thermal conductivity increases from (0.124±0.004) W/(m·K) directly after mixing to

(0.191±0.004) W/(m·K) after 24 hours of curing.

12 mm

epoxy

Curing at RT

Linear Fit of Rth over BLT

ASTM D 5470

Tobias von Essen

27 June 2019

𝑅𝑡ℎ𝑒𝑓𝑓 =Δ𝑇

𝑄

𝑅𝑡ℎ𝑒𝑓𝑓 = 𝑅𝑡ℎ𝑏𝑢𝑙𝑘 + 𝑅𝑡ℎ0

0

1RthBLT

ARth

bulk

eff +

=

Rth

BLT

bulk

1~

The linear fit over BLT bears information about bulk thermal

conductivity and the effective thermal interface resistance

𝑄 =∆𝑇𝑅𝐵

𝑙𝑅𝐵𝐴𝑅𝐵 𝜆𝑅𝐵

Heater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y

heat

flo

w

(\textit{$\Delta$T}) T3

T4

Rth0.1

Rthbulk

Rth0.2

TIMA®Thermal Interface Material Analyzer

27 June 2019

Tobias von Essen

examples of feasible material samples

selection of available test heads

Material Parameters

» Conform to ASTM-D5470 standard

» Effective and bulk thermal conductivity

» Thermal effective and interface resistance

» Compact all-in-one system

Feasible Samples

» Thermal interface

materials

» Die attach materials

» Underfill materials

» Molding compound

» Substrates

» Foils

» Multilayer samples

test chip for application-related studies

Unique Selling Points of TIMA®

» Conformity to standard ASTM D5470 for TIM characterization

» Characterization under application-related or any other customer-specific conditions

27 June 2019

Tobias von Essen

Heater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y

TTV

Cooler

sample

T4

T5

T6

Lo

wer

refe

ren

ce b

od

y

T0

Measurement between

silicon and metal surfaces• real application case for TIM1

• Using In-house developed

Thermotest module with

integrated heater and

temperature sensors

Application of different

metals as contacting surface

material

In-situ investigation of aging

behavior of TIM

Preparation of cured samples

in desired bond line thickness

Application-specific definition

of contacting surface finishing

F F

Thermal characterization of thermal grease

Highly filled polymer

» Eff. thermal resistance over bond line thickness

→ Bulk thermal conductivity and contact resistance

» Thickness range 25 to 200 µm

» 60°C sample temperature

Tobias von Essen

27 June 2019

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0 50 100 150 200

Rth

[cm

²K/W

]

Thickness [µm]

R² = 0.99902

λbulk = ± 0.11 W/mK; Interface resistance Rth,0=5.05 0.015 ± 0.002 cm²K/W

Thermal characterization of gap filler

Tobias von Essen

27 June 2019

non-cured

cured for 1 hour at 150°C

0,0

0,5

1,0

1,5

2,0

2,5

0 200 400 600 800 1000

Rth

[K/W

]

BLT [µm]

data points

linear fit

R² = 0.99991

λbulk = 2.97 ± 0.08 W/mK

Rth,0 = 0.14 ± 0.01 K/W

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

0 100 200 300 400 500 600 700

Rth

[K

/W]

BLT [µm]

data points

linear fit

R² = 0.99981

λbulk = 3.03 ± 0.09 W/mK

Rth,0 = 0.12 ± 0.01 K/WHeater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y heat fl

ow

Gap filler Assembly tool

TIM under test in TIMA

TIM layer after test

Some Gap Filler measured at cured and non-cured state

Thickness [µm]

Thickness [µm]

» Mechanical or thermal cycling

» Combined loading

» In-situ measurement of BLT and pressure

» In-situ measurement of thermal resistance

» Computer-controlled long term testing

Ageing investigations with TIMA®

27 June 2019

Tobias von Essen

2

2,5

3

3,5

4

4,5

5

5,5

6

6,5

7

0 500 1000

therm

al re

sist

an

ce [

K/W

]

cycle count

Step 1

Step 2

RB

expansion

compression

⇅ RB

RB

⇅ RB

Step 1 Step 2

T

timeΔporΔd

Mechanical loading

Thermal loading

Co

mb

ined

load

ing

TIM

RB

expansion

compression

⇅ RB

TIM

RB

TIM

RB

⇅ RB

Exa

mp

le Two-component gap filler» initial thickness 300 µm

» 10 % expansion at 80°C

» +90% Rth increase after 1000 cycles

https://linustechtips.com

aged thermal grease layer

LaTIMA® Lateral Thermal Interface Materials Analyzer

» In-plane thermal conductivity measurement of high thermally conductive materials

27 June 2019

Tobias von Essen

sample

sample

sampleQ

TRth

=

Cooler

T4

T5

T6

Heater

T3

T2

T1

1stre

fere

nce

bo

dy

2n

dre

fere

nce

bo

dy

IR

ΔT

Heat flow Q

L

Sample

Heater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y

transform

LaTIMA®Lateral Thermal Interface Material Analyzer

27 June 2019

Tobias von Essen

Material Characterization of Highly Conductive Materials

Feasible Samples

» Metals & alloys

» Substrates & ceramics

» Solder

» Sintered material

» Semiconductors

Material Parameters

» In-plane thermal conductivity

» Thermal diffusivity

(available with TIMA™wave add-on module)

Processing-Structure-Property Correlations of Sintered Silver

27 June 2019

sample, L=20 mm,

W=5 mm, T=150

µm

Samples

preparation,

variation of sinter

parameters

Structure analysis by FIB and SEM

Measurement of thermal

conductivity by LaTIMA

Thermal conductivities as

function of sintering parameters

Thermal conductivity as function of porosity

Tobias von Essen

TIMA®wave

Measurement of in-plane thermal diffusivity of substrate (e.g. AlN, Al2O3, Si3N4 etc.), die attach (e.g. solder, sinter Ag, sinter Cu etc.), metals and alloys

27 June 2019

I

R

Lock-in

processing

Amplitude

and phase

informatio

n𝑇 𝑡 = 𝐴 ∙ sin(𝜔𝑡)

Laser

driver

Power

supply

Sample

Temperature stage

Thermal isolating

Induction

heater

IR cam

Sample

Laser

Inducti

on

heater

x

Amplitude Image

Phase Image

𝑘𝑎𝑚𝑝

𝑘𝑝ℎ𝑎

𝑘𝑎𝑚𝑝

𝑘𝑝ℎ𝑎

Am

pli

tud

e

x

Ph

ase

Tobias von Essen

Thermal diffusivity results

» metals and metals alloys

» ceramics

» semiconductors

27 June 2019

5 mm

Cu

Cu

Zn

Ag

Al

Si Si Si Si

CeramicsMetalsSemiconductors

Thermal diffusivity of different materials at room temperaturesThermal diffusivity of low and high doped Si at different

temperatures

Tobias von Essen

Thermal characterization of carbon fiber reinforced polymer

Carbon fiber composite panel

Material

T700 Toray unidirectional carbon fiber, EPIKOTE Resin MGS

L135, EPIKURE Curing Agent MGS H137; hand layup with

vacuum bagging at 100%, 50% and 0% of full vacuum to

vary void content [1]

[1] I. Hakim, D. May, M. Abo Ras, N. Meyendorf, S. Donaldson, Quantifying voids effecting delamination in

carbon/epoxy composites: static and fatigue fracture behaviour, Proc.SPIE 9806, 9806H1 (2016).

Vacuum bagging

Sample cutting

2 mm0.2 mm

InitialAfter preparation

Tobias von Essen

27 June 2019

Characterization with LaTIMA® 24

Dan R. Wargulski

30. Jan. 2019

Cooler

T4

T5

T6

Heater

T3

T2

T1

1stre

fere

nce

bo

dy

2n

dre

fere

nce

bo

dy

IR

ΔT

Heat flow Q

L

Sample

Sample Thermal

conductivity

[W/(m∙K)]

Error

[W/(m∙K)]

CFRP_x 6.2 ±1.5

CFRP_y 4.5 ±1.5

x

zy

sample

Linear Fit of Rth over BLT

TIMA® ASTM D 5470 Conformity

Tobias von Essen

27 June 2019

𝑅𝑡ℎ𝑒𝑓𝑓 =Δ𝑇

𝑄

𝑅𝑡ℎ𝑒𝑓𝑓 = 𝑅𝑡ℎ𝑏𝑢𝑙𝑘 + 𝑅𝑡ℎ0

0

1RthBLT

ARth

bulk

eff +

=

Rth

BLT

bulk

1~

The linear fit over BLT bears information about bulk thermal

conductivity and the effective thermal interface resistance

𝑄 =∆𝑇𝑅𝐵

𝑙𝑅𝐵𝐴𝑅𝐵 𝜆𝑅𝐵

Heater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y

heat

flo

w

(\textit{$\Delta$T}) T3

T4

Rth0.1

Rthbulk

Rth0.2

Thermal characterization of substrates

High surface roughness → high interface resistance

→ interface resistance dominates

Use of thermal interface material or liquid metal in contact

areas

→ elimination of the interface resistance

Heat sink

TTC

refe

rence

sock

et

T3

T2

T1

DUT

Liquid metal

20 40 60 80 100

12

14

16

18

20

22

24

26

28

30

Rth

[m

m²K

/W]

BLT [µm]

Km

W

sbulk ==

2,13,8

1

Hot plate

Coldplate

Substrate

Rth0,1

Rth0,2

RthsubRtheff

voids

Hot plate

Coldplate

Substrate

Rth0,1 ~0

Rth0,2 ~0

RthsubRtheff

Liquid metal

Liquid metal

(61.0Ga/25.0In/13.0Sn/1.0Zn)

Heater

Cooler

sample

T1

T2

T3

T4

T5

T6

Up

per

refe

ren

ce b

od

yLo

wer

refe

ren

ce b

od

y

Liquid metal

Tobias von Essen

27 June 2019

Carbon fiber reinforced polymer

50 %Vacuum 100

% 0 %

» Thermal conductivity increases as the vacuum level increases, due to

decreasing void content

𝜆 = 0.75 W/mK 𝜆 = 0.69 W/mK 𝜆 = 0.64 W/mK

Direction Bulk thermal conductivity

W/mK for vacuum 100%

Longitudinal (fiber direction) > 4.5 ± 0.02

Transverse (90o to fiber

direction)

0.80 ± 0.02

Cross-plane 0.75 ± 0.02

Tobias von Essen

27 June 2019

IR-thermography for void detection

27 June 2019

Tobias von Essen

50% vacuum level

PPT-amplitude image 50%_#26_T

PPT-phase image 50%_#26_T

PT- image 50%_#26_T

PPT-amplitude image 100%_#16_B

PPT-phase image 100%_#16_B

PT- image 100%_#16_B

100% vacuum level

Vacuum Level Void volume fraction

0 % 3.7 %

50 % 3.1 %

100 % 1.3 %

» Defects visible in amplitude and phase images.

27 June 2019

Tobias von Essen

Basic principle of thermal imaging based FA

cam

good

bad

Lab scale equipment

27 June 2019

Tobias von Essen

IR

camera

funnel

attachment

Fresnel lens

attachment

Trigger and

synchronization unit

molded APC

samples

DEMO TRT#1, delamination die attach

DEMO APC#1, void in molded QFN

→Successful detection of failure: delam. and void

Comparison high-end and low-cost Camera

SAM PIRT (high-end) PIRT (low-budget)

X1_1_1

Tobias von Essen

→Flash IR pulsed experiment on DEMO APC#1 also successfully

→Low-cost provide good results at much lower form factor and lower costs

→Enables cost efficient FA systems

27 June 2019

INFAS - Modular building kit for in-line quality assessment

27 June 2019

Tobias von Essen

Range of detectable defects

🞂 Voids and material inclusions

🞂 Delamination

🞂 Cracks and lift-offs

🞂 Compact form factor

🞂 Contact-less measurement

🞂 Results within seconds

🞂 Complete solution in hard- and software

🞂 Open and flexible system design

🞂 Adaptable to special customer needs

Unique selling points

Voids in solder die attach layer

Voids in carbon fiber reinforced

polymerVoids in molding compound

Delamination in sintered power

module

IRca

m

conveyor belt

Sinter layer

delamination

Void in mold

compound

INFAS - Modular building kit for in-line quality assessment

27 June 2019

Tobias von Essen

Excitation sources Thermal imaging systems

€€

€€ €€

Co

mp

on

en

t su

pp

liers

Pro

du

ctio

n

lin

eIN

FAS

Computation

exc

ita

tio

n

resp

onse

Failure analysis hardware | custom fusion of

excitation and imaging hardware

Analysis software

image processing,

defect localization

and decision making

based on

machine learning

Conclusion

» Reliability is greatly about thermal performance

» It begins with the ingredients, it ends with the process

» Different material requires different approaches

» Flaws and defects may be anywhere

» We offer full-range support for thermal questions

27 June 2019

Tobias von Essen

Thanks for Your attention

nanotest.eu

27 June 2019

Tobias von Essen