FVTX substrate FEA1 FVTX Substrate FEA C. M. Lei March 02, 2006

FVTX substrate FEA2 Goals To use FEA as a design tool to understand what kind of adhesives and substrate should be used for achieving a mimimal thermal displacement. – Options of substrate cf/TPG/cf aluminum – Options of adhesives Silicone glue (E = 2 Mpa) Epoxy glue (E = 500 ~ 6,900 Mpa)

FVTX substrate FEA3 The Layup of the Multi-chip Module substrate

FVTX substrate FEA4 FEA Model Half Modules with 4 chips (took advantages of symmetry and all modules evenly positioned) Bump bond layer were modeled as a continous layer with adjusted properties based on an area ratio (with eutectic solder bond diameter mm assumed). Effective Heat flux from ROC = mW/mm^2 Effective heat flux from sensor = 0.25 mW/mm^2 Total heat load = 2.8W for half model Cooling contact area 5mm wide at +7C

FVTX substrate FEA5 Material Library Used in this FEA Temp in KK in W/m-K All materials were assumed to be isotropic with constant properties except - TPG in which the thermal conductivity varies - Anisotropic carbon fiber facing and bump bonds Young’s modulus E, MPa Poison’s ratio Thermal k, w/m-K CTE  HDI30e e-6 Silicone glue e-6 Silicon sensor110e e-6 Silicon ROC110e e-6 Epoxy (silver filled) 500 ~ 6, e-6 TPG83e30.20table-1e-6 Eutectic solder32e e-6 TPG Thermal K Carbon fiber 0/90facing: E inplane = 1.48e5 Mpa, E out-of-plane =7445 Mpa, k inplane = W/mK, k out-of-plane = 0.69 W/mK, a inplane = -0.04e-6 ppm/K, a out-of-plane =30.17e-6 ppm/K Eutectic solder bump bond layer: Ex = Ez = 0.15 Mpa, Ey = 1500 Mpa, kx = kz = 0.33e-3 W/mK, ky = 2.38 W/mK, a = 24.7e-6 ppm/K

FVTX substrate FEA6 Silicon as substrate glue Epoxy as electrical glue Overall ∆T = 19.9C From +7C to +26.9C RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, 4 Combinations of Adhesives Epoxy thermal k = 1.59W/mK, cte = 49 ppm/K; silicone thermal k = 0.24W/mK, cte = 100 ppm/K Silicon as substrate glue Silicon as electrical glue Overall ∆T = 22.0C From +7C to +29C Epoxy as substrate glue Epoxy as electrical glue Overall ∆T = 17.9C From +7C to +24.9C Heat Load = 2.28W, Half Model with 4 chips Epoxy as substrate glue Silicone as electrical glue Overall ∆T = 20C From +7C to +27.0C

FVTX substrate FEA7 RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS SUBSTRATE GLUE IS SILICONE (E=2 Mpa ) ELECTRICAL GLUE VARIETY AS SHOWN BELOW E = 500 Mpa (epoxy) Max resultant disp. = 2.09 microns E = 1,200 Mpa (epoxy) Max resultant disp. = 2.23 microns E = 6,900 Mpa (epoxy) Max resultant disp. = 4.47 microns Heat Load = 2.28W, Half Model with 4 chips E = 2 Mpa (silicon) Max resultant disp. = 3.66 microns

FVTX substrate FEA8 RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS SUBSTRATE GLUE IS EPOXY (E=500 Mpa ) ELECTRICAL GLUE VARIETY AS SHOWN BELOW Heat Load = 2.28W, Half Model with 4 chips E = 500 Mpa (epoxy) Max resultant disp. = 12.1 microns E = 1,200 Mpa (epoxy) Max resultant disp. = 17.4 microns E = 2 Mpa (silicon) Max resultant disp. = 15.4 microns

FVTX substrate FEA9 Silicon as substrate glue Epoxy as electrical glue Overall ∆T = 17.2C From +7C to +24.2C RESULTS WITH ALUMINUM SUBSTRATE 1/16” ( mm) COOLING AT ENDS, 4 Combinations of Adhesives Epoxy thermal k = 1.59W/mK, cte = 49 ppm/K; silicone thermal k = 0.24W/mK, cte = 100 ppm/K Heat Load = 2.28W, Half Model with 4 chips Epoxy as substrate glue Silicone as electrical glue Overall ∆T = 17.2C From +7C to +24.2C Epoxy as substrate glue Epoxy as electrical glue Overall ∆T = 15.2C From +7C to +22.2C Silicon as substrate glue Silicon as electrical glue Overall ∆T = 19.2C From +7C to +26.2C

FVTX substrate FEA10 Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH ALUMINUM SUBSTRATE 1/16” ( mm) COOLING AT ENDS SUBSTRATE GLUE IS SILICONE (E=2 Mpa ) ELECTRICAL GLUE VARIETY AS SHOWN BELOW E = 1,200 Mpa (epoxy) Max resultant disp. = 30.8 microns E = 500 Mpa (epoxy) Max resultant disp. = 29.9 microns E = 2 Mpa (silicone) Max resultant disp. = 22.2 microns

FVTX substrate FEA11 Heat Load = 2.28W, Half Model with 4 chips E = 500 Mpa (epoxy) Max resultant disp. = 62.3 microns E = 1,200 Mpa (epoxy) Max resultant disp. = 57 microns RESULTS WITH ALUMINUM SUBSTRATE 1/16” ( mm) COOLING AT ENDS SUBSTRATE GLUE IS EPOXY (E=500 Mpa ) ELECTRICAL GLUE VARIETY AS SHOWN BELOW E = 2 Mpa (silicone) Max resultant disp. = 29.2 microns

FVTX substrate FEA12 RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm

FVTX substrate FEA13 RESULTS WITH ALUMINUM SUBSTRATE 1/16” ( mm) Displacements higher than those of cf/TPG/cf substrate

FVTX substrate FEA14 Quick Conclusions Cf/TPG/cf substrate performed better with less thermal displacement Silicone glue should be used for the thermal substrate. Basically any epoxy can be used for the electrically conductive adhesive, but flexible one with lower modulus is preferred.

FVTX substrate FEA15 Material Selections Carbon fiber facing – 2 plies,0 o and 90 o Bryte K139-BT250, 55 gsm, 0.12 mm thick TPG – 0.38 mm thick Substrate adhesive – NEE001 silicone glue Module adhesive – MasterBond MB21 TDXSFL. ( Minimum order is 20 $25 per gram. If too costly, can use Tra-duct 2902 which is currently being used at Sidet and has a higher thermal conductivity at 2.99 W/mK.) More plots follow based on these selections.

FVTX substrate FEA16 Overall ∆T = 19.9C From +7C to +26.9C RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy Heat Load = 2.28W, Half Model with 4 chips ∆T, sensor/ROC = 3.3C From +23.6C to +26.9C Mid-section all layers Overall ∆T = 8.3C From +18.6C to +26.9C 22.0C 26.5C 26.9C ∆T across HDI (from 22C to 26,5C) = 4.5C 19.7C sensorTPGHDI

FVTX substrate FEA17 Stress Z Plot (out-of-plane 90 0 direction) Heat Load = 2.28W, Half Model with 4 chips TPG Layer Max Resultant Stress = 0.9 Mpa Max Stress_Z = 0.1 Mpa Flexural Strenth = 36.7 Mpa Z = 38.5 Mpa // Tensile Strength < 0.69 Mpa Z = 6,897 Mpa // RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA18 Carbon Fiber Layer Max Resultant Stress = 0.7 Mpa Max Stress_Z = 0.2 Mpa Flexural Strenth = 669 Mpa 0 0 Tensile Strength =1950 Mpa 0 0 = 28 Mpa 90 0 Stress Z Plot (out-of-plane 90 0 direction) Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA19 Silicone Glue Layer between HDI and Substrate (E = 2 Mpa) Max Stress = 0.02 Mpa Strength_NEE001 = 1.1 Mpa Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA20 HDI Layer Max Stress = 4.5 Mpa Tensile Strength_Kapton = 166 Mpa Tensile Strength_Copper = 320 MPa Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA21 Module Glue Layer (E = 500 Mpa) Max Stress = 0.6 Mpa Shear Strength_MB21 TDCSFL = 6 Mpa Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA22 Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK! Sensor and ROC Layers Max Stress = 2.4 Mpa Strength_Si = 120 MPa

FVTX substrate FEA23 Bump Bond Layer Max Stress = 0.34*21.33 = 7.2 MPa Strength of eutect solder Tensile Yield = 43 Mpa Ultimate = 52 MPa Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA24 When heat load = 0, Temperature everywhere at +7C Max resultant disp. = 42.2 microns Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA25 Stress Z Plot (out-of-plane 90 0 direction) Heat Load = 2.28W, Half Model with 4 chips TPG Layer Max Resultant Stress = 7.5 Mpa Max Stress_Z = 0.56 Mpa Flexural Strenth = 36.7 Mpa Z = 38.5 Mpa // Tensile Strength < 0.69 Mpa Z = 6,897 Mpa // RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy OK!

FVTX substrate FEA26 Carbon Fiber Layer Max Resultant Stress = 6.2 Mpa Max Stress_Z = 1.1 Mpa Flexural Strenth = 669 Mpa 0 0 Tensile Strength =1950 Mpa 0 0 = 28 Mpa 90 0 Stress Z Plot (out-of-plane 90 0 direction) Heat Load = 2.28W, Half Model with 4 chips OK! RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA27 Silicone Glue Layer between HDI and Substrate (E = 2 Mpa) Max Stress = 0.07 Mpa Strength_NEE001 = 1.1 Mpa Heat Load = 2.28W, Half Model with 4 chips OK! RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA28 HDI Layer Max Stress = 6.8 Mpa Tensile Strength_Kapton = 166 Mpa Tensile Strength_Copper = 320 MPa Heat Load = 2.28W, Half Model with 4 chips OK! RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA29 Module Glue Layer (E = 500 Mpa) Max Stress = 2.1 Mpa Shear Strength_MB21 TDCSFL = 6 Mpa Heat Load = 2.28W, Half Model with 4 chips OK! RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA30 Heat Load = 2.28W, Half Model with 4 chips OK! Sensor and ROC Layers Max Stress = 10.4 Mpa Strength_Si = 120 MPa RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy

FVTX substrate FEA31 Bump Bond Layer Strength of eutect solder Tensile Yield = 43 Mpa Ultimate = 52 MPa Heat Load = 2.28W, Half Model with 4 chips RESULTS WITH CF/TPG/CF SUBSTRATE 0.62 mm ( ) mm COOLING AT ENDS, POWER OUTAGE Substrate Glue: Silicone; Module Glue: 500 Mpa Epoxy Resultant stress in most area = 0.030*21.33 = 0.64 Mpa…OK Resultant stress in most area = 0.006*21.33 = 0.13 Mpa…OK Max resultant stress = 3.04*21.33 = 64.8 Mpa Resultant stress at corner = 0.97*21.33 = 20.7 Mpa…OK Could fail at corners locally