high-performance carbon-based thermal management...

High-Performance Carbon-Based Thermal Management Materials

September 25, 2013

Copyright: Carl Zweben 1

ADVANCED CARBON-BASED THERMAL MANAGEMENT MATERIALS AND APPLICATIONS

Carl Zweben Ph D

Copyright Carl Zweben 1Copyright Carl Zweben

Carl Zweben Ph. D.Life Fellow, ASME; Fellow ASM and SAMPE; Assoc. Fellow, AIAA

Advanced Thermal Materials Consultant

Presenter Contact Information:E-mail: [email protected]: http://sites.google.com/site/zwebenconsultingAll materials copyrighted by Carl Zweben

SPONSORED BY:


OUTLINE

• Introduction• Traditional thermal management materials• Advanced carbon-based thermal management

materials• Applications


• Future directions• Summary and conclusions

INTRODUCTION

Copyright Carl Zweben 4

POLL QUESTION


INTRODUCTION

• Heat dissipation critical in electronics and photonics

• Thermal stresses also critical, resulting in• Warping• Fracture• Fatigue failure


• Creep• Premature failure

• Reducing Size, Weight and Power (SWaP) key driver for many aerospace/defense and commercial applications– Thermal management critical to meet goals


September 25, 2013


INTRODUCTION (cont)


Source: US Air Force

Copyright Carl Zweben

INTRODUCTION (cont)

• Traditional thermal materials increasingly inadequate for many applications– Date from mid 20th Century– Can impose severe design and weight

limitations– Some expensive


– Some expensive• Increasing number of advanced carbon-based

materials– Thermal conductivities up to 5300 W/m-K– Low CTEs– Low densities– R&D to large volume production

• Numerous traditional and new thermal materials– Many engineers only familiar with copper and

aluminum• More complete coverage in

– One-day to three-day short courses (in-house, IEEE SPIE Semitracks)

INTRODUCTION (cont)


IEEE, SPIE, Semitracks)– Papers

• Webinar focuses on materials used in heat sinks, heat spreaders, enclosures, etc.

• Thermal interface materials (TIMs) using advanced carbon-based materials under development

PACKAGING LEVELSAdvanced Materials Used In All

H t Si k


Source: US Air Force (modified)

Heat Sink (Cold Plate)


TRADITIONAL THERMAL MANAGEMENT MATERIALS


LARGE VARIATIONS IN REPORTED MATERIALPROPERTIES VERY COMMON

MaterialK

MeanW/m-K

KMinimum

W/m-K

KMaximum

W/m-K

Kmax/Kmin

CVD

MEASURED THERMAL CONDUCTIVITIESIN ROUND ROBIN TESTS – 14 LABS, 5 METHODS


CVD Diamond

1370 706 1601 2.8

SiC 268 192 357 1.9

AlN 178 141 368 2.6

“Report on a second round robin measurement of the thermal conductivity of CVD diamond”, J.E. Graebner, et al., Diamond and Related Materials 7 (1998).


September 25, 2013


SEMICONDUCTOR AND CERAMIC SUBSTRATE CTEs

MATERIAL CTE (ppm/K)Silicon 2.5-4.1GaAs 5.8-6.9GaN 5.4-7.2GaP 5.9Ge 5.9InP 4.5-4.8


SiC 2.8-5.1Alumina (96%) 6.0-7.1AlN 3.5-5.7LTCC 4.5-7.0

CTE RANGE ~ 2 – 7 ppm/K

TRADITIONAL THERMAL AND PACKAGING MATERIALS

k CTE DensityMATERIAL (W/m-K) (ppm/K) g/ccCopper 400 17 8.9Aluminum 218 23 2.7---------------------------------------------------------------------------------------“Kovar” 17 5.9 8.3Titanium 6.7 8.6 4.4---------------------------------------------------------------------------------------Tungsten 164 4.2 19.3


Tungsten 164 4.2 19.3Molybdenum 142 5.2 10.2W/Cu (85/15) 167 6.5 17Mo/Cu (85/15) 184 7.0 10Cu-Invar-Cu (x,y) 164 8.4 8.4Cu-Mo-Cu (x,y) 182 6.0 9.9---------------------------------------------------------------------------------------E-glass/epoxy (x,y) 0.3 12-24 1.6-1.9


CLASSES OF ADVANCED THERMAL MATERIALS

• Monolithic carbonaceous materials• Composite materials

– Two or more materials bonded together– Used for many years, e.g.

• FR-4 glass/epoxy, copper/tungsten, etc.• Types of composites


ypes o co pos tes– Polymer matrix composites (PMCs)– Metal matrix composites (MMCs)– Carbon matrix composites (CAMCs)– Ceramic matrix composites (CMCs)– Metal/metal alloys-composites

ADVANCED CARBON-BASED THERMAL MANAGEMENT MATERIALS


ADVANTAGES OF CARBON-BASED THERMAL MANAGEMENT MATERIALS

• Extremely high thermal conductivities– Up to 5300 W/m-K (13X copper)

• Low CTEs– Composite CTEs tailorable

• Very high stiffnesses and strengths (some)


Very high stiffnesses and strengths (some)• Low densities

DISADVANTAGES OF CARBON-BASED THERMAL MANAGEMENT MATERIALS

• Higher cost – depends on competing materials• Possible development cost to implement• Hysteresis in carbon fiber/aluminum and

carbon fiber/copper metal matrix composites• Plating may require development


g y q p– New materials

• Diamond-based materials hard to machine• Galvanic corrosion issue for carbon/aluminum

– Plating may prevent


September 25, 2013


DIAMOND AND GRAPHITE STRUCTURES

a,b

c

AMORPHOUS ORDERED GRAPHENE


Sources: Panasonic, NASA and Wikipedia

GRAPHITE GRAPHITE

DIAMOND CRYSTALFace-Centered Cubic

SHEET

SINGLE-WALL NANOTUBE

CVD DIAMOND

• Well-established thermal management materials• Electrically insulating• Several Chemical Vapor Deposition (CVD)

processes – produce different properties• Thermal Conductivities up to 2000 W/m-K• Low CTE (~1 ppm/K) can cause tensile thermal

t l d


stresses on cool down• Directionality of thermal conductivity

– Some forms strongly anisotropic• E.g. inplane = 11-50% of vertical

– Some effectively isotropic• Some show through-thickness property variability• Price increases with increasing conductivity


CVD DIAMOND

Property

Inplane Thermal Conductivity W/m-K 200-2000

Vertical Thermal Conductivity*, W/m-K 200-2000

Inplane CTE, ppm/K ~ 1


Modulus, GPa 1050 - 1280

Density, g/cc 3.52

* Some forms strongly anisotropic

INDUSTRIAL GRAPHITE - Type AXF-5Q

Property

Thermal Conductivity W/m-K 95

Inplane CTE, ppm/K 7.9

Total Porosity, % 20


Open Porosity, % 80

Density, g/cc 1.78

Source: Poco Graphite

THERMALLY-CONDUCTIVE GRAPHITE FOAM

Property PocoFoam

HTCFoam

Inplane Thermal Conductivity W/m-K 45 70

Vertical Thermal Conductivity, W/m-K 135 245


Inplane CTE, ppm/K - 0.7 - 1.07

Density, g/cc 0.55 0.9


PYROLYTIC GRAPHITE SHEET - PGS

Property 0.1mm

0.07 mm

0.025 mm

Inplane Thermal Conductivity, W/m-K 600-800

750-950

1500-1700

Vertical Thermal Conductivity, W/m-K ~ 15 ~ 15 ~ 15


Source: Panasonic

Inplane CTE, ppm/K 0.93 0.93 0.93

Vertical CTE, ppm/K 32 32 32

Density, g/cc 0.85 1.1 2.1


September 25, 2013


FLEXIBLE GRAPHITE

• Exfoliated natural graphite used as a thermal interface material (TIM) for many years

• Highly anisotropic flexible, foil-like material• Now widely used as heat spreader• Higher thermal conductivities made by pyrolysis process

Property

Inplane Thermal Conductivity W/m-K 140 - 1500


Source: GrafTech


p y

Vertical Thermal Conductivity, W/m-K 3 - 10

Inplane CTE, ppm/K - 0.4

Vertical CTE, ppm/K 27

Density, g/cc 1.1 - 1.9

HIGHLY-ORIENTED PYROLYTIC GRAPHITE (HOPG)

• Strongly anisotropic• Very high inplane thermal conductivities• Very low through-thickness thermal

conductivities• Weak material, especially interlaminar


• Typically used in encapsulated form• Encapsulation material CTE possibly decoupled

from HOPG


HIGHLY-ORIENTED PYROLYTIC GRAPHITE (HOPG)

Property

Inplane Thermal Conductivity W/m-K 1300 - 1700

Vertical Thermal Conductivity, W/m-K ~ 25


Source: Advanced Ceramics Corp




Density, g/cc 2.26

Al/SiC-ENCAPSULATED HOPG

Property

Inplane Thermal Conductivity W/m-K ~ 1000

HOPG Aluminum Interface


Inplane Thermal Conductivity W/m-K ~ 1000

Vertical Thermal Conductivity, W/m-K Design Dependent

Inplane CTE, ppm/K 8.0

Al/SiC Modulus, GPa 188

Density, g/cc < 3.01Source: CPS Technologies

SINGLE-LAYER GRAPHENE SHEETMultiple-Layer Conductivity Lower – Phonon

Transport Effect

Property

Inplane Thermal Conductivity W/m-K 5300


Modulus, GPa ~ 1000

Inplane CTE, ppm/K - 8

GRAPHENE (GRAPHITE) NANOPLATELET SHEETS

Property

Inplane Thermal Conductivity W/m-K > 400

Vertical Thermal Conductivity, W/m-K 2 - 4


Inplane CTE, ppm/K -


Source: XG Sciences


September 25, 2013


MULTILAYER GRAPHENE FILM, CHIPS AND BLOCKS

Property

Inplane Thermal Conductivity W/m-K > 1000


Inplane Thermal Conductivity W/m K > 1000

Vertical Thermal Conductivity, W/m-K > 300

Inplane CTE, ppm/K -

Density, g/cc < 2

Source: Angstron Technologies

POLL QUESTION


CARBON AND DIAMOND COMPOSITES


THERMALLY CONDUCTIVE CARBON-BASED REINFORCEMENTS

Continuous Carbon Fibers

Discontinuous Carbon Fibers, CNTs


Diamond & Graphite Particles,

Platelets, Fabrics, Braids, etc.

DIAMOND AND CARBON REINFORCEMENTS

Material Density Thermal Modulus CTEg/cc Conductivity GPa ppm/K

W/m-KNatural diamond 3.5 600-2200* 1050 0.8

Diamond fiber - 1300-1700 1000 0.8-1.5

SW** CNT - theory 1.4 6600 1000 -

SW** CNT - measured - 5800 - - 1.5


Gr Nanoplatelets ~ 2.0 3000 1000 - 1.0Single Layer Graphene - 5300 1000 - 8

*3300 – Isotope **Single wall


THERMALLY-CONDUCTIVE CARBON FIBERS

Fiber Type Mfr Density Axial AxialName g/cc Modulus Thermal

GPa ConductivityW/m-K

KI3D2U C,2 M 2.2 930 800YS-95A C, 2 N 2.2 920 600---------------------------------------------------------------------------------------------XN-100 D,2 N 2.2 900 900


,DKD D,1 C 2.2 700 - 840 400 - 650VGCF* D,3 A - 600 1500

C: Continuous, D: Discontinuous1: Petroleum pitch based, 2: Coal tar pitch based Mfr: A- Applied Sciences, C - Cytec, M - Mitsubishi Chemical, N - Nippon Graphite Fiber*VGCF: Vapor-Grown Carbon Fiber



September 25, 2013


INPLANE CTE OF CARBON FIBER/ALUMINUM [0/90] vs FIBER VOLUME FRACTION

CT

E, p

pm

/K


Inp

lan

e C

Fiber Volume Fraction (%)


INPLANE THERMAL CONDUCTIVITY OF CARBON FIBER/ALUMINUM [0/90] vs FIBER VOLUME FRACTION

ne

Th

erm

al

tivi

ty,

W/m

-K


Inp

lan

Co

nd

uct

Fiber Volume Fraction (%)

DIAMOND PARTICLE/COPPER CTE vs PARTICLE VOLUME FRACTION


Source: Yoshida & Morigami; Sumitomo


THERMAL CONDUCTIVITY OF DIAMOND /COPPER vs PARTICLE SIZE AND VOLUME FRACTION


Source: Yoshida & Morigami; Sumitomo

NATURAL GRAPHITE/EPOXY FIN STOCK

Property


Vertical Thermal Conductivity, W/m-K 6.5

Exfoliated natural graphite particles bonded with epoxy to form rigid plates – HS 400




Inplane Elastic Modulus, GPa 42

Density, g/cc 1.9Source: GrafTech

ULTRAHIGH-THERMAL CONDUCTIVITYCARBON FIBER/EPOXY – QUASI-ISOTROPIC

Fiber Volume Fraction = 60%

Property


Vertical Thermal Conductivity, W/m-K 10



Elastic Modulus, GPa 165

Density, g/cc 1.80


September 25, 2013


COPPER-IMPREGNATED INDUSTRIAL GRAPHITE Type AXF-5QC

Property


C / 8


CTE, ppm/K 8.7

Density, g/cc 3.12


DISCONTINUOUS THERMALLY CONDUCTIVE CARBON FIBER/COPPER - MMC

Property Cu METGRAF™

4-280

Cu METGRAF™

7-300

Inplane Thermal Conductivity W/m-K 265-280 285-300



Inplane CTE, ppm/K 4 7

Vertical CTE, ppm/K 16 16


Source: Metal Matrix Cast Composites, Inc.

Property AlGrp4-750

AlGrp7-650

Inplane Thermal Conductivity W/m-K 750 650


GRAPHITE PLATELET/ALUMINUM - MMC


Inplane CTE, ppm/K 4 7


Source: Metal Matrix Cast Composites, Inc.

DIAMOND-PARTICLE/COBALT(POLYCRYSTALLINE DIAMOND COMPACT)

Property

Thermal Conductivity W/m-K > 600

CTE, ppm/K 3.0

Widely used in rock drill and saws



Density, g/cc 4.12

Source: Element Six

DIAMOND PARTICLE/COPPER - MMC

Property

Thermal Conductivity W/m-K 226 - 800

CTE /K 4 12


CTE, ppm/K 4 - 12


Sources: Various vendors and papers

DIAMOND PARTICLE/ALUMINUM

Property


CTE, ppm/K 6.1



Density, g/cc 3.17

Sources: NMIC


September 25, 2013


DIAMOND PARTICLE/SILVER - MMC

Property

Thermal Conductivity W/m-K 350 - 983


CTE, ppm/K 4.5 - 7.5


Sources: Weber, various vendors and papers

CARBON/CARBON COMPOSITES

Property Unidirectional1D

2D

Thermal Conductivity (x) W/m-K 800 350

Thermal Conductivity (y), W/m-K 45 350

Thermal Conductivity (x), W/m-K 45 40


CTE (x), ppm/K - 1 1

CTE (y), ppm/K 6.5 1

CTE (x), ppm/K 6.5 2.5


Source: MER

POLL QUESTION


APPLICATIONS


MONOLITHIC ADVANCED CARBON-BASED


MATERIAL APPLICATIONS


FLEXIBLE CVD DIAMOND HEAT SPREADERSMITIGATE THERMAL STRESSES


Source: Diamond Materials GmbH


September 25, 2013


NATURAL GRAPHITE THERMAL INTERFACE MATERIALS (TIMs) USED FOR MANY YEARS


Source: Keratherm


NOTEBOOK COMPUTER WITH FLEXIBLE GRAPHITE HEAT SPREADERS


Source: GrafTech


FLEXIBLE GRAPHITE WIDELY USED IN SMART PHONES, TABLETS AND DISPLAYS


Source: GraphTech


FLEXIBLE GRAPHITE SOLID STATE LIGHTING (LED) APPLICATIONS


Source: GrafTech

BTeV PIXEL TEVATRON COLLIDER DETECTOR USES HOPG (“TPG”) AND PGS FOR THERMAL

MANAGEMENT

HOPG (“TPG”)

PGS


Source BTeV collaboration:


HOPG (“TPG”)Substrate

HOPG-ENHANCED PCB INCREASES LED ARRAY OUTPUT BY 60%


Source: k-Technology



September 25, 2013


ALUMINUM-ENCAPSULATED “TC1050” HOPG INSERTS


Source: GE Advanced Materials


HOPG INSERTS ENHANCE HEAT-SPREADING CAPABILITY OF Al/SiC COLD PLATES AND LIDS


Source: CPS Technologies


HOPG

POLL QUESTION


CARBON-BASED AND DIAMOND-BASED


COMPOSITE MATERIALS APPLICATIONS


eGRAF® NATURAL-GRAPHITE/EPOXYHEAT SPREADERS


Source: GraphTech


HEAT SINK WITH eGRAF® NATURAL-GRAPHITE/EPOXY FINS


Source: GraphTech


September 25, 2013


CONTINUOUS THERMALLY CONDUCTIVE CARBON FIBER/EPOXY PCB COLD PLATE


Source: XC Associates


DIE

2.5 ppm/oC

DIE

2.5 ppm/oC

CARBON FIBER/POLYMER PCB CONSTRAINING LAYER

Unconstrained PCB Constrained PCB


DIELECTRIC

DIELECTRIC

17-19 ppm/oC

STABLCORDIELECTRIC

2 - 8 ppm/oC

DIELECTRIC

Source: ThermalWorks/Stablcor

THERMALLY CONDUCTIVE CARBON FIBER-COOLED PCB


Source: Maxwell

THERMALLY-CONDUCTIVE CARBON/EPOXYSPACECRAFT ELECTRONICS ENCLOSURE


Source: COI


DISCONTINUOUS CARBON FIBER/COPPER CELLULAR TELEPHONE BASE STATION FLANGES


Source: MMCC

“AlGrp” GRAPHITE PLATELET/ALUMINUM COMPONENTS


Source: Metal Matrix Cast Composites



September 25, 2013


ELECTRONIC ENCLOSURE INCORPORATES METAL MATRIX COMPOSITES

• 2.4x Aluminum Thermal Conductivity• 10% Lighter


Source: Curtiss-Wright

Patent Cites Carbon-based thermal materials

DIAMOND-PARTICLE METAL MATRIX COMPOSITESUSED IN INDUSTRIAL APPLICATIONS FOR DECADES


Sources: Kunime et al.; Element Six

Diamond Particle/Copper Grinding Wheel Blank

Diamond Particle/Cobalt Rock Drill Bits


DIAMOND-PARTICLE/COPPERLASER DIODE HEAT SPREADERS


Source: Sumitomo


DIAMOND PARTICLE/ALUMINUM GaN RF FLANGESNICKEL & GOLD PLATED


Source: NMIC

HIGH-POWER GaN SPACECRAFT PACKAGE HASDIAMOND PARTICLE/SILVER BASEPLATE


Source: Thales Alenia Space, Plansee

AGAPAC Project: Advanced GaN Package

for Space

FUTURE DIRECTIONS



September 25, 2013


FUTURE DIRECTIONS

• Thermal management will continue to be a problem in electronic and photonic packaging (e.g. LEDs)

• 3D architecture adds complexity• Continuing development of new materials

– Monolithic carbonaceous– Composites


Composites– Thermal interface materials (TIMs)

• Reinforcements– Carbon nanotubes and nanofibers (6,000 W/m-K)– Natural graphite platelets (3000 W/m-K)– Diamond particles (2,200 W/m-K)– Electrically nonconductive particles and fibers


FUTURE DIRECTIONS (cont)

• Graphene very attractive– 5300 W/m-K - single layer

• Thermally conductive, electrically insulating materials

• Other materials possible– E.g. boron arsenide predicted thermal


E.g. boron arsenide predicted thermal conductivity > 2000 W/m-K


SUMMARY AND CONCLUSIONS


SUMMARY AND CONCLUSIONS

• Thermal management critical problem in electronic and photonic systems– Heat dissipation– Thermal stresses and warping

• Size, weight and power critical• Traditional materials have significant deficiencies


• Traditional materials have significant deficiencies• Increasing number of carbon-based materials

– Thermal conductivities up to 5300 W/m-K– Low CTEs– Low densities– Applications increasing steadily

WE ARE IN THE EARLY STAGES OF ATHERMAL MATERIALS REVOLUTION

Find more information on advanced thermal management materials at electronics-cooling.com.


For questions regarding this webinar or any of the topics we covered, email [email protected]

Contact Carl at [email protected]

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