Thermal Management Solutions for Automotive, Lighting and Industrial Applications

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1 Thermal Management Solutions for Automotive, Lighting and Industrial Applications UL Prospector Webinar, January 25, 2018 Presented by Florian Damrath & Julien Renaud Technical Service & Development, Advanced Assembly Dow.com

2 Agenda Why Thermal Conductivity? Common Language Analogies to Thermal System Resistance and Conductivity Why Silicones? Adhesives Gap Fillers Dispensable Pads Greases Encapsulants/Gels 2

3 Why Thermal Conductivity? Smaller, faster and more power = more heat per unit of volume Functions of thermally conductive materials Carry heat transfer AWAY from components Electrical insulation between components and casing Flexible fixation Stress relieve from thermal effect Stable over various operating conditions and environments Benefit Removing heat allowing greater miniaturization & more reliable power module performance 3

4 Common Language Thermal management Thermal Conductivity Thermal Energy Temperature Temperature Difference Junction Temperature Heat Transfer Thermal Resistance Heat Flux Power 4

5 Common Language Term Definition Symbol Unit(s) Heat Thermal energy in transfer Q [or E] Joule, J Heat flux / Heat flow Flowing heat per time Qdot [or P or H] Joule per second = Watt, J / s = W Temperature difference Difference in temperature between two points ΔT [or Δθ] Degree celsius, ºC or Kelvin, K Thermal conductivity (TC) Material property; its ability to transfer heat λ (lambda) [or κ (kappa)] Watt per (meter Kelvin), W / (m K) Absolute thermal resistance The ΔT needed to cause a Qdot Rth Degree celsius per watt, ºC / W or K / W 5

6 Analogies to Thermal System Water Electrical Thermal Height Difference Big Stones Water stream Voltage Electrical Resistance Current Temperature Difference Thermal Resistance Heat Flux What is flowing? What does it need to drive it? What is the >>resistance<<? Thermal Resistance = ΔT [ºC] Qdot [W] 6

7 What Influences Thermal Resistance? Surface (Length and Width) Thickness of Transfer Layer (BLT) Hot Body Interface Material Cold Body Material Property: Thermal Conductivity (λ) Thermal Resistance = BLT [mm] 1000 λ [W / (m K)] Length [mm] Width [mm] 7

8 Higher Thermal Conductivity (TC) Higher filler loading leads to higher thermal conductivity; filler with high TC value delivers high TC material. Thermal Conductivity as a Function of Al2O3 Wt% K (W/mK) Wt% Al2O3 Viscosity / rheology Elongation / modulus Bondline thickness Thermal stability Dielectric properties Price 8

9 Why Silicone for Thermally Conductive Applications? Thermal stability High temperature resistance Wide temperature range retention of elastomeric properties Tunable modulus/hardness Manipulate hardness from hard to soft depending on application Flexible/compliant Retains flexibility at high filler content 9

10 Why Silicone for Thermally Conductive Applications? High thermal conductivity capabilities at lower viscosity Retains flowable viscosity at high filler content Low energy surface Good wetting properties to minimize contact thermal resistance Electric insulator Chemical stability Hydrophobic (waterproof) Heat Sink Thermal Interface Material Die With thick bondline, bulk properties are dominant. Heat Sink Contact Resistance Thermal Interface Material Contact Resistance Die With thin bondline, wet ability and contact resistances are dominant. 10

11 Range of Thermally Conductive Materials Adhesives Silicone adhesive with thermal conductivity Improved stability over time Can replace mechanical fixation Insulator or electrically conductive Gap Fillers Soft and compressible/stress relieving Ideal for applications where large gap tolerances are present, typically 150µm to 5 mm Non-flowable Limited adhesion Dispensable Thermal Pads Improved alternative to thermal pads (performance/cost) Flowable Thermal Greases Non-curing paste Low thermal resistance capabilities (thin bondline, high thermal conductivity) Limited adhesion Soft and compressible/stress relieving Limited stability Need mechanical fization Encapsulants & Gels Protection and heat dissipation Flowable Low modulus/stress relieving With or without adhesion 11

12 Webinar Watch the recorded webinar and learn about the less-obvious ways that your choice of adhesives can make your process more efficient. Request the slides presented during the webinar here. 12

13 Thermally Conductive Adhesives Property Condensation Cure (1-Part) Addition Cure (1-Part / 2-Part) Thermal Radical Cure (1-Part) Cure Temperature Room Temperature Heat Mild Heat Humidity Needed to Cure Yes No No Viscosity Range Flowable to Thixotropic Flowable to Thixotropic Thixotropic Thermal Conductivity Range [W/mK] 0.8 to to

14 Thermally Conductive Adhesives Benefits Field-proven adhesion Broad portfolio of solutions Fast curing, short cycle times possible Electrically conductive options available Limitations Addition cure / Thermal Radical Cure needs: Mixing (two components) or cold storage (one component) Heat to develop adhesion RTV cure: slow cure and limited surface area 14

15 Thermally Conductive Adhesives Portfolio Product TC (W/m-K) Form Cure Conditions P E R F O R M A N C E DOWSIL TC-2035 Thermally Conductive Adhesive DOWSIL SE 4485 Thermally Conductive Adhesive Part ºC Part RTV 120 RT* (Fast TFT) DOWSIL TC-2030 Adhesive Part ºC DOWSIL Thermally Conductive Adhesive DOWSIL SE 4486 Thermally Conductive Adhesive DOWSIL Thermally Conductive Adhesive DOWSIL SE 4420 Thermally Conductive Adhesive Part ºC Part RTV 72 RT* (Fast TFT) Part ºC Part RTV 72 RT* (Fast TFT) DOWSIL EA-9189 H Part RTV 72 RT* (Fast TFT) DOWSIL Q Thermally Conductive Adhesive Part ºC * Cure time for moisture cure adhesives depends on many factors including, ambient temperature, material thickness and relative humidity of cure environment 15

16 DOWSIL EA-9189 H Cost competitive, easy-to-use, 1-Part RTV adhesive with stable properties after environmental aging Properties Unit Measure Color - White Extrusion Rate g/min 815 Specific Gravity 1.68 Thermal Conductivity W/mK 0.88 Dielectric Strength (1 mm) kv/mm 28 Volume Resistivity Ohm.cm 3.3E W/mK thermally conductive adhesive Excellent dispensing properties Wide adhesion profile Fast, tack-free time Low amount of silicone volatiles UL approved (UL94 V-0) Particularly suitable for lighting applications 16

17 DOWSIL TC-2035 Thermally Conductive Adhesive Enhanced thermal resistivity by high thermal conductivity; low BLT and good wetting with electrical insulation Properties Unit Measure Color - Part A - White Color - Part B - Reddish Brown Viscosity Pa s 125 Specific Gravity 3.0 Thermal Conductivity W/mK 3.3 Dielectric Strength (2 mm) kv/mm 21 Volume Resistivity Ohm.cm 5.5E W/mK thermally conductive adhesive 2-Part system <80μ of minimum BLT Adhesion to metals at low temperature cure profile ( o C) Retains suitable elastomeric modulus after environmental aging Good property stability during shelf-life Particularly suitable for demanding automotive applications 17

18 Range of Thermally Conductive Materials Adhesives Silicone adhesive with thermal conductivity Improved stability over time Can replace mechanical fixation Insulator or electrically conductive Gap Fillers Soft and compressible/stress relieving Ideal for applications where large gap tolerances are present, typically 150µm to 5 mm Non-flowable Limited adhesion Dispensable Thermal Pads Improved alternative to thermal pads (performance/cost) Flowable Thermal Greases Non-curing paste Low thermal resistance capabilities (thin bondline, high thermal conductivity) Limited adhesion Soft and compressible/stress relieving Limited stability Need mechanical fization Encapsulants & Gels Protection and heat dissipation Flowable Low modulus/stress relieving With or without adhesion 18

19 Gap Fillers Benefits Soft and compressible Maintain good interface contact with low stress Vibration dampener Excellent mechanical and elastomeric stability during temperature aging Fast, heat cure or room-temperature cure Non-flowable for thicker bondline, highly thixotropic for fast processing Cost competitive Limitations Thin bondline (<150 µm) No chemical bonding, tack adhesion only Two components only 19

20 Gap Fillers Portfolio Product TC (W/m-K) Form Cure Conditions DOWSIL TC-4525 Thermally Conductive Gap Filler DOWSIL TC-4515 Thermally Conductive Gap Filler >2.5 2-Part >1.5 2-Part 2 25ºC 10 80ºC 2 25ºC 30 80ºC Available options Glass beads for distance control Low, controlled amount of Si volatiles Nomenclature TC Gap Filler 1.5 W/m.K Thermal Conductivity 20

21 DOWSIL TC-4525 Thermally Conductive Gap Filler Optimize customers modules performance at lower total cost of ownership Properties Unit Measure Color - Part A - White Color - Part B - Blue Viscosity (Mixed) Pa s 217 Density (Cured) g/cm Hardness Shore Thermal Conductivity W/mK 2.6 Cure Conditions 2 25ºC 10 80ºC Dielectric Strength (2 mm) kv/mm 18 Improved properties Reliability; better stability of properties during aging (thermal, modulus) Optimized dispensability (minimized abrasion, improved rheology) Optimized assembly process; better compressibility/ spread-ability Faster cure to reduce process costs Competitive market pricing 21

22 Range of Thermally Conductive Materials Adhesives Silicone adhesive with thermal conductivity Improved stability over time Can replace mechanical fixation Insulator or electrically conductive Gap Fillers Soft and compressible/stress relieving Ideal for applications where large gap tolerances are present, typically 150µm to 5 mm Non-flowable Limited adhesion Dispensable Thermal Pads Improved alternative to thermal pads (performance/cost) Flowable Thermal Greases Non-curing paste Low thermal resistance capabilities (thin bondline, high thermal conductivity) Limited adhesion Soft and compressible/stress relieving Limited stability Need mechanical fization Encapsulants & Gels Protection and heat dissipation Flowable Low modulus/stress relieving With or without adhesion 22

23 Thermal Pads Fabricated vs. Dispensable A fabricated pad is coated onto some kind of liner, cured, and then cut into pieces for use, such as a gap pad. A dispensable pad is applied to a substrate in its wet state and cured in place. The pad may be screen or stencil printed, or dispensed. 23

24 Dispensable Thermal Pads Dispensable pads are similar to gap fillers, with lower viscosity for screen or stencil printing processes. Benefits Use as printable pad or dispense like a traditional liquid gap filler Material is less expensive than fabricated pad (30% 60%) Design flexibility (geometry, small shapes) Can attain thinner bondlines than fabricated pad Limitations No chemical bonding, tack adhesion only Two components only Limited vertical holding capabilities before cure 24

25 Dispensable Thermal Pads Portfolio P E R F O R M A N C E Product DOWSIL TC-4025 LV Dispensable Thermal Pad DOWSIL TC-4026 Dispensable Thermal Pad DOWSIL TC-4015 Dispensable Thermal Pad TC (W/m-K) Viscosity Mix (Pa.s) 174 µm Glass Beads No Yes No DOWSIL TC Yes 25

26 DOWSIL TC-4026 Dispensable Thermal Pad Dispensable thermal pad with high thermal conductivity and glass beads for bondline control 2.5 W/mK Thermally conductive printable or dispensable pad 2-Part system with fast, heat or roomtemperature cure 174 µm glass beads for bondline control Particularly suitable for LED lamp and luminaires, automotive and consumer applications Properties Unit Measure Color Part A - White Color Part B - Blue Viscosity Pa s 70 Specific Gravity 2.83 Thermal Conductivity W/mK Cure Conditions W/mK 24 25ºC ºC Dielectric Strength kv/mm 18 26

27 Range of Thermally Conductive Materials Adhesives Silicone adhesive with thermal conductivity Improved stability over time Can replace mechanical fixation Insulator or electrically conductive Gap Fillers Soft and compressible/stress relieving Ideal for applications where large gap tolerances are present, typically 150µm to 5 mm Non-flowable Limited adhesion Dispensable Thermal Pads Improved alternative to thermal pads (performance/cost) Flowable Thermal Greases Non-curing paste Low thermal resistance capabilities (thin bondline, high thermal conductivity) Limited adhesion Soft and compressible/stress relieving Limited stability Need mechanical fization Encapsulants & Gels Protection and heat dissipation Flowable Low modulus/stress relieving With or without adhesion 27

28 Thermally Conductive Compounds Benefits Lowest thermal resistance No cure No mixing; easy dispensing Good conformance to surface irregularities Very thin layers Low interfacial contact resistance Limitations No cure Pump-out under cycling Risk of bleeding Aging at very high temperatures Electrical insulation not warranted 28

29 Thermal Stability Performance Common stability failure mechanisms for greases: Pump-out Substrate flexing due to CTE mismatch moves material from interface and replaces with voids Bleeding Liquid polymer separates from conductive filler particles Dry-out Polymer matrix separates from conductive filler particles and dry the grease at accelerated environmental conditions No pump-out Pump-out 29

30 Thermal Stability Performance Common stability failure mechanisms for greases: Phase separation Polymer and filler components separate in the packaging (settlement) Vertical slide Thermal interface material exits vertical substrates under gravitational forces No pump-out Pump-out 30

31 Thermally Conductive Compounds Portfolio P E R F O R M A N C E Product DOWSIL TC-5888 Thermally Conductive Compound DOWSIL TC-5622 Thermally Conductive Compound DOWSIL TC-5351 Thermally Conductive Compound DOWSIL TC-5026 Thermally Conductive Compound DOWSIL TC-5121 C LV Thermally Conductive Compound DOWSIL SE 4490CV Thermally Conductive Compound DOWSIL TC-5080 Thermally Conductive Compound TC (W/m-K) Thermal 40 psi (C-cm 2 /W) ASTM D5470 Bondline 40 psi (µm) DOWSIL SC 102 Compound

32 DOWSIL TC-5622 Thermally Conductive Compound High thermal conductivity and improved stability Very high thermal performance High thermal conductivity Thin bondline capabilities Improved stability Enhanced dry-out resistance versus other highly filled compounds Improved rheology Easy to screen print Properties Unit Measure Color - Gray Viscosity mpa s Specific Gravity 2.5 Thermal Conductivity (transient) W/mK 4.3 Thermal 25 N/cm² ºC.cm²/W 0.06 Bondline 25 N/cm² µm 20 32

33 DOWSIL TC-5622 Thermally Conductive Compound High thermal conductivity and improved stability Solvent-less formulation: Fewer volatiles in manufacturing environment Less weight for fixed volume applied Lower specific gravity than standard grease: Less weight for fixed volume applied Particularly suitable for power modules Properties Unit Measure Color - Gray Viscosity mpa s Specific Gravity 2.5 Thermal Conductivity (transient) W/mK 4.3 Thermal 25 N/cm² ºC.cm²/W 0.06 Bondline 25 N/cm² µm 20 33

34 Range of Thermally Conductive Materials Adhesives Silicone adhesive with thermal conductivity Improved stability over time Can replace mechanical fixation Insulator or electrically conductive Gap Fillers Soft and compressible/stress relieving Ideal for applications where large gap tolerances are present, typically 150µm to 5 mm Non-flowable Limited adhesion Dispensable Thermal Pads Improved alternative to thermal pads (performance/cost) Flowable Thermal Greases Non-curing paste Low thermal resistance capabilities (thin bondline, high thermal conductivity) Limited adhesion Soft and compressible/stress relieving Limited stability Need mechanical fization Encapsulants & Gels Protection and heat dissipation Flowable Low modulus/stress relieving With or without adhesion 34

35 Thermally Conductive Encapsulants and Gels Benefits Low viscosity Combine protection and heat dissipation Low modulus Primerless options available Limitations Trade of between thermal conductivity and viscosity/ hardness/modulus Filler settlement 35

36 Encapsulants and Gels Portfolio P E R F O R M A N C E Product DOWSIL TC-6020 Thermally Conductive Encapsulant TC (W/m-K) Viscosity Mix (mpa.s) Hardness Shore A DOWSIL SE 4445 CV Gel mm/10 DOWSIL TC-4605 (HLV) Thermally Conductive Encapsulant (1900) 35 (65) Shore A DOWSIL SE 4440 LP mm/10 SYLGARD Q Thermally Conductive Encapsulant Shore A SYLGARD 160 Silicone Elastomer Shore A DOWSIL EE-3200 Low Stress Encapsulant Shore

37 DOWSIL TC-6020 Thermally Conductive Encapsulant High thermal performance High thermal conductivity versus viscosity Improved processing High flowability Fast curing with moderate heat Improved stability Wide operating temperature range Properties Unit Measure Color - Gray Viscosity (Mixed 1:1) mpa s Thermal Conductivity W/mK 2.72 Specific Gravity 2.9 Dielectric Strength kv/mm 24 Durometer Shore A 63 Adhesion to aluminum Excellent dielectric properties Particularly suitable for automotive and power modules applications Cure Conditions ºC 23 60ºC 5 100ºC 37

38 Expanded Portfolio of Advanced Thermally Conductive Materials Product Type W/mK 1 W/mK 2 W/mK 3 W/mK 4 W/mK 5 Adhesives DOWSIL Q Adhesive DOWSIL Adhesive DOWSIL TC-2022 Adhesive DOWSIL EA-9189 H DOWSIL SE 4486 Adhesive DOWSIL TC-2030 Adhesive DOWSIL TC-2035 Adhesive Gap Fillers DOWSIL TC-4515 Gap Filler DOWSIL TC-4525 Gap Filler Dispensable Pads DOWSIL TC-4015 Dispensable Pad DOWSIL TC-4016 Dispensable Pad DOWSIL TC-4025 LV Dispensable Pad DOWSIL TC-4026 Dispensable Pad Greases DOWSIL TC-5080 Compound DOWSIL SE 4490 CV Compound DOWSIL TC 5026 Compound DOWSIL TC-5121 C LV Compound DOWSIL TC 5351 Compound DOWSIL TC 5622 Compound DOWSIL TC 5888 Compound Encapsulants/ Gels DOWSIL Q Encapsulant DOWSIL TC-4605 Encapsulant DOWSIL TC-4605 HLV Encapsulant DOWSIL SE-4445 CV Gel DOWSIL TC-6020 Encapsulant 38

39 Questions? Visit our website: consumer.dow.com/pcbsystemassembly Contact us: dowcorning.com/contactus 39

40 Thank You Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow The Corning portion of the Dow Corning trademark is a trademark of Corning Incorporated, used under license The Dow Chemical Company. All rights reserved. Form No