Thermal Symposium August Minteq International, Inc. Pyrogenics Group A Thermal Management Solution for State-of-the-Art Electronics

Transcription

1 Thermal Symposium August Minteq International, Inc. Pyrogenics Group A Thermal Management Solution for State-of-the-Art Electronics Mark Breloff Technical Sales Manager 1

2 Electronics power requirements are steadily increasing leading to increasing thermal management problems. Generally, the lifespan of semiconductor devices is halved for every 10 Deg. rise in junction temperature.

3 Carbon Nanotubes: Thermal Management Material for the Next Century? 3

4 Pyroid HT Pyrolytic Graphite Pyrolytic Graphite: Thermal Management Material For Today Pyrolytic Graphite is 3 Dimensional graphene, CVD deposition atom-by-atom on a substrate Continuous layers with hexagonal structure, like a deck of cards. Highly anisotropic the properties being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. Turbostratic Structure of Pyrolytic Graphite J.C. Bokros, Properties of Pyrolytic Carbon, pg 10, Chemistry and Physics of Carbon, 1969, Marcel Dekker, Inc, New York

5 Thermal Challenges are Driving a Renewed Review of Graphite Spreader Materials BUT NOT ALL GRAPHITES ARE THE SAME! Natural Graphite Spreader micrograph Natural graphite heat spreader material Static imperfections limited columnar structure and alignment dislocations point defects 100 µm Pyroid HT micrograph Pyroid HT Pyrolytic Graphite Light weight High purity (>99.999%) No porosity Substantial columnar structure High purity with no point defects Polycrystalline Structure Highly Oriented Approaches theoretical carbon density

6 Pyroid HT Pyrolytic Graphite Diamond Like Performance Without the Diamond Price Features: High Thermal Conductivity (2 Directions) 1700 W/mK (typical) Light weight - density = 2.25 g/cc Lower CTE - a closer match to power devices than Cu Tailored thickness or shapes Easily cut, diced and lapped Accepts Metallic Coatings Customer Benefits: Significant thermal spreading Fast and Uniform Thermal Response Weight savings Direct solder attachment Increased component reliability Lowered system costs

7 Pyroid HT Pyrolytic Graphite Metalized Coatings Electroless, Electrolytic, and Sputtering coating processes Thin, multiple layers of electronic grade coatings for sealing and soldering including: 5 mm 3 mm Ti/NiCr/Au Ti/Ni/Au Ti/Pt/Au Cu Cu/Au Ni NiCr Failures in the material Not in the metallization interface

8 Case Study - Laser Diode Z Y X Heat Sink Laser Diode High Conductivity Directions Heat Spreader Finite control volume computational grid laser diode attached to the heat spreader Two dimensional heat spreader configuration High conductivity plane Constant heat flux 200 W/cm 2 Copper heat sink temperature 30 o C

9 Case Study : Laser Diode Resultant Temperature Contours for Pyroid HT Pyrolytic Graphite v. CuMo heat spreaders Silicon die, k = 150 Cu-Mo spreader, k = 160 Cu heat sink, k = 400 Z X Y T Silicon die Pyroid HT Pyrolytic Graphite Spreader Cu heat sink Z X Y T Cu-Mo K = 160 W/m- o K Pyroid HT Pyrolytic Graphite K = 1700 W/m- o K High thermal gradients Low and uniform thermal gradient Resultant Temperature Contours for Pyroid HT Pyrolytic Graphite v. CuMo heat spreaders for a heat flux of 200 W/cm 2

10 Case Study - Laser Diode RESULTS: 70 o C REDUCTION in T junction Experimental Results Interface Temperature 160 Cu-Mo Cu 70 o C Temperature (deg. C) Pyroid HT Pyrolytic Graphite 200 W/cm 2 flux Resulting interface Temp reduction Delta T junction = 70 o C Spreader

11 Case Study - Laser Diode RESULTS: POTENTIAL TO INCREASE POWER OUTPUT Interface temperature for Cu v. CuMo v. PG-HT heat spreaders 1000 Maximum Interface Temperature on the Diode (deg C) Cu Spreader, k = 400 W/mK Pyroid HT Pyrolytic Graphite, k = 1700, 10 CuMo Spreader, k = 160 Change in temperature with spreader type 100 Heat sink Temperature 30 o C For constant Tjunction = 100 o C power output INCREASES > 50% over CuMo Heat Flux (W/ cm 2 )

12 Three Dimensional CTE Stress Analysis: MODULUS OF ELASTICITY KEY PROPERTY Properties of die and spreader materials Material CTE (1/ºC) E, modulus of elasticity, (GPa) Silicon 4.68 x PYROID HT Pyrolytic Graphite 0.5 x x 10-6 < 50 Diamond 1.18 x Copper 16.5 x For 200 o C temperature excursion thermal stresses for various die/spreader materials Resultant governing system equation: ( A B ) T E AE ( E E ) A B B

13 Three Dimensional CTE Stress Analysis For 200 o C temperature excursion thermal stresses for various die/spreader materials Die/spreader Materials Silicon/Diamond Stress, MPa (psi) -71 (-10,260) (die compression) Silicon/Copper Silicon/PYROID HT Pyrolytic Graphite Silicon/PYROID HT Pyrolytic Graphite 130 (18,900) (die tension) 4.8 (697) (die tension) -11 (-1600) (die compression) Order magnitude lower than diamond or copper

14 Pyroid HT Pyrolytic Graphite High Performance Applications Al Cu HT High thermal conductivity (1700 W/mK) But weighing 75% less than copper! Diamond like performance without the diamond like price

15 Pyroid HT Heat Sink/Spreaders Thermal Performance Modeling Finned Heat Sink: Convection 1700 W/m K 1700 W/m K theoretical model applied to single fin Fin Thermal Conduction Heat Load Base Thermal Conduction Heat Load Flat Plate Heat Sink: Fluid Flow Heat Load Numerical model calculated Over a computational mesh D. Sabatino and K. Yoder, "Pyrolytic Graphite Heat Sinks: A Study of Circuit Board Applications," in IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 4, no. 6, pp , June 2014.

16

17

18 Finned Heat Sink Model - OUTPUTS

19 Finned Heat Sink Model - OUTPUTS

20 Finned Heat Sink Model - OUTPUTS

21 Finned Heat Sink Model Design 1

22 Finned Heat Sink Model Design 2 Thinner fins

23 Finned Heat Sink Model Design 3 Reduced airflow

24 Flat Plate Model

25 Pyroid HT Pyrolytic Graphite Material Provides: DIAMOND LIKE PERFORMANCE WITHOUT THE DIAMOND LIKE PRICE Pyroid HT Pyrolytic Graphite Customer Benefits: Significant thermal spreading Fast and Uniform Thermal Response Weight Savings Direct solder attachment For a copy of the Pyroid HT Software Modeling Tool Mark.breloff@minteq.com

26 Thank You For a Copy of Pyroid HT Software Modeling Tool Mark.breloff@Minteq.com