High-Performance Carbon-Based Thermal Management Materials September 25, 2013

Transcription

1 ADVANCED CARBON-BASED THERMAL MANAGEMENT MATERIALS AND APPLICATIONS SPONSORED BY: Carl Zweben Ph. D. Life Fellow, ASME; Fellow ASM and SAMPE; Assoc. Fellow, AIAA Advanced Thermal Materials Consultant Presenter Contact Information: Website: All materials copyrighted by Carl Zweben 1 2 OUTLINE Introduction Traditional thermal management materials Advanced carbon-based thermal management materials Applications Future directions Summary and conclusions INTRODUCTION 3 4 INTRODUCTION POLL QUESTION 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 5 6 1

2 INTRODUCTION (cont) INTRODUCTION (cont) Source: US Air Force Traditional thermal materials increasingly inadequate for many applications Date from mid 20 th Century Can impose severe design and weight limitations 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 7 8 INTRODUCTION (cont) 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) 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 LEVELS Advanced Materials Used In All Heat Sink (Cold Plate) Source: US Air Force (modified) 9 10 LARGE VARIATIONS IN REPORTED MATERIAL PROPERTIES VERY COMMON MEASURED THERMAL CONDUCTIVITIES IN ROUND ROBIN TESTS 14 LABS, 5 METHODS TRADITIONAL THERMAL MANAGEMENT MATERIALS Material K Mean W/m-K K Minimum W/m-K K Maximum W/m-K Kmax/ Kmin CVD Diamond SiC AlN 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)

3 SEMICONDUCTOR AND CERAMIC SUBSTRATE CTEs MATERIAL CTE (ppm/k) Silicon GaAs GaN GaP 5.9 Ge 5.9 InP SiC Alumina (96%) AlN LTCC CTE RANGE ~ 2 7 ppm/k TRADITIONAL THERMAL AND PACKAGING MATERIALS k CTE Density MATERIAL (W/m-K) (ppm/k) g/cc Copper Aluminum Kovar Titanium Tungsten Molybdenum W/Cu (85/15) Mo/Cu (85/15) Cu-Invar-Cu (x,y) Cu-Mo-Cu (x,y) E-glass/epoxy (x,y) 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 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) 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 New materials Diamond-based materials hard to machine Galvanic corrosion issue for carbon/aluminum Plating may prevent

4 DIAMOND AND GRAPHITE STRUCTURES a,b AMORPHOUS ORDERED GRAPHENE GRAPHITE GRAPHITE SHEET DIAMOND CRYSTAL Face-Centered Cubic c SINGLE-WALL NANOTUBE Sources: Panasonic, NASA and Wikipedia 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 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 INDUSTRIAL GRAPHITE - Type AXF-5Q Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity*, W/m-K Inplane CTE, ppm/k ~ 1 Modulus, GPa Density, g/cc 3.52 Thermal Conductivity W/m-K 95 Inplane CTE, ppm/k 7.9 Total Porosity, % 20 Open Porosity, % 80 Density, g/cc 1.78 * Some forms strongly anisotropic Source: Poco Graphite THERMALLY-CONDUCTIVE GRAPHITE FOAM PYROLYTIC GRAPHITE SHEET - PGS Poco Foam HTC Foam Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity, W/m-K Inplane CTE, ppm/k Density, g/cc Source: Poco Graphite 0.1 mm Inplane Thermal Conductivity, W/m-K mm mm Vertical Thermal Conductivity, W/m-K ~ 15 ~ 15 ~ 15 Inplane CTE, ppm/k Vertical CTE, ppm/k Density, g/cc Source: Panasonic

5 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 Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity, W/m-K 3-10 Inplane CTE, ppm/k Vertical CTE, ppm/k 27 Density, g/cc Source: GrafTech 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) Al/SiC-ENCAPSULATED HOPG Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity, W/m-K ~ 25 Inplane CTE, ppm/k Vertical CTE, ppm/k 25 Density, g/cc 2.26 Source: Advanced Ceramics Corp HOPG Inplane Thermal Conductivity W/m-K ~ 1000 Aluminum Interface Vertical Thermal Conductivity, W/m-K Design Dependent Inplane CTE, ppm/k 8.0 Al/SiC Modulus, GPa 188 Density, g/cc < 3.01 Source: CPS Technologies SINGLE-LAYER GRAPHENE SHEET Multiple-Layer Conductivity Lower Phonon Transport Effect GRAPHENE (GRAPHITE) NANOPLATELET SHEETS Inplane Thermal Conductivity W/m-K 5300 Modulus, GPa ~ 1000 Inplane CTE, ppm/k - 8 Inplane Thermal Conductivity W/m-K > 400 Vertical Thermal Conductivity, W/m-K 2-4 Inplane CTE, ppm/k - Density, g/cc Source: XG Sciences

6 MULTILAYER GRAPHENE FILM, CHIPS AND BLOCKS Inplane Thermal Conductivity W/m-K > 1000 POLL QUESTION Vertical Thermal Conductivity, W/m-K > 300 Inplane CTE, ppm/k - Density, g/cc < 2 Source: Angstron Technologies THERMALLY CONDUCTIVE CARBON-BASED REINFORCEMENTS Continuous Carbon Fibers Discontinuous Carbon Fibers, CNTs CARBON AND DIAMOND COMPOSITES Diamond & Graphite Particles, Platelets, Fabrics, Braids, etc DIAMOND AND CARBON REINFORCEMENTS Material Density Thermal Modulus CTE g/cc Conductivity GPa ppm/k W/m-K Natural diamond * Diamond fiber SW** CNT - theory SW** CNT - measured Gr Nanoplatelets ~ Single Layer Graphene *3300 Isotope **Single wall THERMALLY-CONDUCTIVE CARBON FIBERS Fiber Type Mfr Density Axial Axial Name g/cc Modulus Thermal GPa Conductivity W/m-K KI3D2U C,2 M YS-95A C, 2 N XN-100 D,2 N DKD D,1 C VGCF* D,3 A C: Continuous, D: Discontinuous 1: 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

7 INPLANE CTE OF CARBON FIBER/ALUMINUM [0/90] vs FIBER VOLUME FRACTION INPLANE THERMAL CONDUCTIVITY OF CARBON FIBER/ALUMINUM [0/90] vs FIBER VOLUME FRACTION Inplane CTE, ppm/k Inplan ne Thermal Conduct tivity, W/m-K Fiber Volume Fraction (%) Fiber Volume Fraction (%) DIAMOND PARTICLE/COPPER CTE vs PARTICLE VOLUME FRACTION THERMAL CONDUCTIVITY OF DIAMOND /COPPER vs PARTICLE SIZE AND VOLUME FRACTION Source: Yoshida & Morigami; Sumitomo Source: Yoshida & Morigami; Sumitomo NATURAL GRAPHITE/EPOXY FIN STOCK Exfoliated natural graphite particles bonded with epoxy to form rigid plates HS 400 Inplane Thermal Conductivity W/m-K 370 Vertical Thermal Conductivity, W/m-K 6.5 Inplane CTE, ppm/k Vertical CTE, ppm/k 54 Inplane Elastic Modulus, GPa 42 ULTRAHIGH-THERMAL CONDUCTIVITY CARBON FIBER/EPOXY QUASI-ISOTROPIC Fiber Volume Fraction = 60% Inplane Thermal Conductivity W/m-K 270 Vertical Thermal Conductivity, W/m-K 10 Inplane CTE, ppm/k Elastic Modulus, GPa 165 Density, g/cc 1.80 Density, g/cc 1.9 Source: GrafTech

8 COPPER-IMPREGNATED INDUSTRIAL GRAPHITE Type AXF-5QC DISCONTINUOUS THERMALLY CONDUCTIVE CARBON FIBER/COPPER - MMC Thermal Conductivity W/m-K 175 CTE, ppm/k 8.7 Density, g/cc 3.12 Cu METGRAF Cu METGRAF Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity, W/m-K Inplane CTE, ppm/k 4 7 Vertical CTE, ppm/k Density, g/cc Source: Poco Graphite Source: Metal Matrix Cast Composites, Inc GRAPHITE PLATELET/ALUMINUM - MMC AlGrp AlGrp Inplane Thermal Conductivity W/m-K Vertical Thermal Conductivity, W/m-K Inplane CTE, ppm/k 4 7 Density, g/cc DIAMOND-PARTICLE/COBALT (POLYCRYSTALLINE DIAMOND COMPACT) Widely used in rock drill and saws Thermal Conductivity W/m-K > 600 CTE, ppm/k 3.0 Elastic Modulus, GPa 841 Density, g/cc 4.12 Source: Metal Matrix Cast Composites, Inc. Source: Element Six DIAMOND PARTICLE/COPPER - MMC DIAMOND PARTICLE/ALUMINUM Thermal Conductivity W/m-K CTE, ppm/k 4-12 Density, g/cc Sources: Various vendors and papers Thermal Conductivity W/m-K 500 CTE, ppm/k 6.1 Elastic Modulus, GPa 309 Density, g/cc 3.17 Sources: NMIC

9 DIAMOND PARTICLE/SILVER - MMC CARBON/CARBON COMPOSITES Thermal Conductivity W/m-K CTE, ppm/k Density, g/cc Sources: Weber, various vendors and papers Unidirectional 2D 1D Thermal Conductivity (x) W/m-K Thermal Conductivity (y), W/m-K Thermal Conductivity (x), W/m-K CTE (x), ppm/k CTE (y), ppm/k CTE (x), ppm/k Density, g/cc Source: MER POLL QUESTION APPLICATIONS FLEXIBLE CVD DIAMOND HEAT SPREADERS MITIGATE THERMAL STRESSES MONOLITHIC ADVANCED CARBON-BASED MATERIAL APPLICATIONS Source: Diamond Materials GmbH

10 NATURAL GRAPHITE THERMAL INTERFACE MATERIALS (TIMs) USED FOR MANY YEARS NOTEBOOK COMPUTER WITH FLEXIBLE GRAPHITE HEAT SPREADERS Source: Keratherm Source: GrafTech FLEXIBLE GRAPHITE WIDELY USED IN SMART PHONES, TABLETS AND DISPLAYS FLEXIBLE GRAPHITE SOLID STATE LIGHTING (LED) APPLICATIONS Source: GraphTech Source: GrafTech BTeV PIXEL TEVATRON COLLIDER DETECTOR USES HOPG ( TPG ) AND PGS FOR THERMAL MANAGEMENT HOPG-ENHANCED PCB INCREASES LED ARRAY OUTPUT BY 60% HOPG ( TPG ) PGS HOPG ( TPG ) Substrate Source BTeV collaboration: Source: k-technology

11 ALUMINUM-ENCAPSULATED TC1050 HOPG INSERTS HOPG INSERTS ENHANCE HEAT-SPREADING CAPABILITY OF Al/SiC COLD PLATES AND LIDS HOPG Source: GE Advanced Materials Source: CPS Technologies POLL QUESTION CARBON-BASED AND DIAMOND-BASED COMPOSITE MATERIALS APPLICATIONS egraf NATURAL-GRAPHITE/EPOXY HEAT SPREADERS HEAT SINK WITH egraf NATURAL-GRAPHITE/EPOXY FINS Source: GraphTech Source: GraphTech

12 CONTINUOUS THERMALLY CONDUCTIVE CARBON FIBER/EPOXY PCB COLD PLATE CARBON FIBER/POLYMER PCB CONSTRAINING LAYER Unconstrained PCB 2.5 ppm/ o C DIE Constrained PCB 2.5 ppm/ o C DIE Source: XC Associates DIELECTRIC DIELECTRIC ppm/ o C DIELECTRIC STABLCOR DIELECTRIC 2-8 ppm/ o C Source: ThermalWorks/Stablcor THERMALLY CONDUCTIVE CARBON FIBER-COOLED PCB THERMALLY-CONDUCTIVE CARBON/EPOXY SPACECRAFT ELECTRONICS ENCLOSURE Source: Maxwell Source: COI DISCONTINUOUS CARBON FIBER/COPPER CELLULAR TELEPHONE BASE STATION FLANGES AlGr p GRAPHITE PLATELET/ALUMINUM COMPONENTS Source: MMCC Source: Metal Matrix Cast Composites

13 ELECTRONIC ENCLOSURE INCORPORATES METAL MATRIX COMPOSITES DIAMOND-PARTICLE METAL MATRIX COMPOSITES USED IN INDUSTRIAL APPLICATIONS FOR DECADES 2.4x Aluminum Thermal Conductivity 10% Lighter Patent Cites Carbonbased thermal materials Source: Curtiss-Wright Diamond Particle/Copper Grinding Wheel Blank Diamond Particle/Cobalt Rock Drill Bits Sources: Kunime et al.; Element Six DIAMOND-PARTICLE/COPPER LASER DIODE HEAT SPREADERS DIAMOND PARTICLE/ALUMINUM GaN RF FLANGES NICKEL & GOLD PLATED Source: NMIC Source: Sumitomo HIGH-POWER GaN SPACECRAFT PACKAGE HAS DIAMOND PARTICLE/SILVER BASEPLATE FUTURE DIRECTIONS AGAPAC Project: Advanced GaN Package for Space Source: Thales Alenia Space, Plansee

14 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 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 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 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 A THERMAL 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, info@electronics-cooling.com Contact Carl at c.h.zweben@usa.net 83 14