The Layup of the Multi-chip Module Note: Assuming all two glues are of silicone type

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 -20C

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 tape 3M e-6 Silicon sensor110e e-6 Silicon ROC110e e-6 Silicone glue NEE e-6 TPG83e30.20table-1e-6 Eutectic solder32e e-6 Carbon fiber facing: E 0 = 411e3 Mpa, E 90 =5852 Mpa, k 0 = 116 W/mK, k 90 = 0.31 W/mK, a 0 = -1.15e-6 ppm/K, a 90 =30.36e-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 TPG Thermal K

Heat Load = 2.28W, Half Model with 4 chips ∆T = 16.2C

Heat Load = 2.28W, Half Model with 4 chips ∆T across TPG = 6C

Heat Load = 2.28W, Half Model with 4 chips ∆T across sensor = 2.4C

∆T across all layers = 10.5C mostly occurred across glue layers Closed-up Mid-sectional view

Heat Load = 2.28W, Half Model with 4 chips Max displacement 0.2 mm

Heat Load = 2.28W, Half Model with 4 chips TPG Layer Max Resultant Stress = 145 Mpa Flexural Strenth = 36.7 Mpa Z = 38.5 Mpa // Tensile Strength < 0.69 Mpa Z = 6,897 Mpa // FAIL!

Heat Load = 2.28W, Half Model with 4 chips Stress Z Plot (out-of-plane direction) TPG Layer Max Stress_Z = 7.8 Mpa Flexural Strenth = 36.7 Mpa Z = 38.5 Mpa // Tensile Strength < 0.69 Mpa Z = 6,897 Mpa // FAIL! Stress Z in most area shown in next slide

Heat Load = 2.28W, Half Model with 4 chips Stress Z Plot (out-of-plane direction) TPG Layer Max Stress_Z = 0.09 Mpa Flexural Strenth = 36.7 Mpa Z = 38.5 Mpa // Tensile Strength < 0.69 Mpa Z = 6,897 Mpa // FAIL!

Carbon Fiber Layer Max Resultant Stress = 311 Mpa Flexural Strenth = 669 Mpa 0 0 Tensile Strength =1950 Mpa 0 0 = 28 Mpa 90 0 Note: carbon fibers are along Y direction

Carbon Fiber Layer Max Stress_X = 15 Mpa Max Stress_Y = 78 Mpa Max Stress_Z = 311 Mpa Flexural Strenth = 669 Mpa 0 0 Tensile Strength =1950 Mpa 0 0 = 28 Mpa 90 0 Stress X Plot (in-plane 90 0 direction) Stress Y Plot (in-plane 0 0 along fiber direction) Stress Z Plot (out-of-plane 90 0 direction) FAIL!

Silicone Glue Layer between HDI and Substrate (E = 2 Mpa) Max Stress = 0.12 Mpa Strength_NEE001 = 1.1 Mpa Stress/Strength ratio = 0.1

HDI Layer Max Stress = 14 Mpa Tensile Strength_Kapton = 166 Mpa Tensile Strength_Copper = 320 MPa

Silicone Glue Layer between HDI and ROC (E = 2 Mpa) Max Stress = 0.07 Mpa Strength_NEE001 = 1.1 Mpa

Sensor and ROC Layers Max Stress = 7.5 Mpa Strength_Si = 120 MPa

Bump Bond Layer Max Stress = 1.79*21.33 = 38.2 MPa Strength of eutect solder Tensile Yield = 43 Mpa Ultimate = 52 MPa Resultant stress in most area = 0.055*21.33 = 1.2 MPa Resultant stress in most area = 0.015*21.33 = 0.3 MPa

Heat Load = 2.28W, Half Model with 4 chips ∆T = 16.1C Repeat FEA with carbon fiber direction in X