EPRC 12 Project Proposal Power Electronics Packaging Solutions for Device Junction Temperature over 220 o C 15 th August 2012 Page 1
Motivation Increased requirements of high power semiconductor device module for future automotive, aerospace and green & renewable energy industry Emerging wide band gap power devices : SiC and GaN can be operated >220 o C Renewable energy Electronic Vehicle 2 Source: Yole Source: Nissan Electronic Railway Source: Infineon Aerospace Hybrid Vehicle Page 2 Source: Toyota
Technology Trends 3 Technology trends for high power module and discrete : High temperature endurable materials >220 o C (silver sintering, encapsulations) High reliable and low stress interconnections (foil interconnects, ultrasonic bonding) Thermal cooling solution (Dual-side cooling / micro-channel cooling ) Source: Yole Page 3
4 Challenges to be Addressed Power Source Interconnection Power cycling endurance Temp cycle endurance Process optimization inter-metallic diffusion Thermal & Electrical properties Substrate (DBC) Temp cycling endurance Adhesion with Encapsulation Adhesion between Cu/Ceramic Surface finish Thermal & Electrical properties Encapsulation Materials Thermal endurance >220C Void free processing Lower stress (CTE, Modulus) High power insulation Moisture barrier Delamination free Power Module Plastic case Encapsulations Diode IGBT DBC substrate Base plate Wire Passive Passive component attach Thermal endurance >220C Void free processing Temp cycle endurance Electrical conductive Metallization > 220C Power Device Attach Thermal endurance >220C Void free processing Lower stress (CTE, Modulus) Electrical conductive Die backside metallization Power Discrete Wire IGBT Heat spreader Base plate (system board) Lead frame Thermal interface materials Thermal endurance > 220C Temp cycle endurance Delamination & fracture Thermal conductivity Reliability testing methodologies Reliability test spec Reliability testing method Failure Analysis / reliability model Modeling and predictions Thermal characterization Mechanical characterization Electro-thermal-mechanical coupling Reliability model (power cycling) Page 4
Objective Development and characterization of power semiconductor packages for high junction temperature endurable (>220 o C) solutions for next generation devices, including the following: Material solutions for TV1 and TV2 High temperature endurable die attach (Ag sintering, TLP bonding, Cu-Cu bonding) DBC surface finish option (Ni/Au finish, ENIG ) High temperature endurable encapsulation materials (High T g EMC) Cu based interconnection through EMWLP RDL process Thermal management solutions for TV1 and TV2 Dual side cooling structure package development and packaging process optimization High temperature endurable, high conductive TIM materials ( Ag sintering ) Package characterization and Reliability for TV1 and TV2 Mechanical &Thermal modeling and characterization Power cycling modeling : electro-thermal- mechanical coupled analysis Reliability and failure analysis Conventional Power Module Diode Plastic case Encapsulations DBC substrate IGBT Project Proposal Wire Passive TV1* : Novel Dual side cooling Power Module Top RDL layer Diode * To be finalized with members input Heat spreader IGBT Page 5 Wire Base plate Conventional Power discrete * IGBT Heat spreader Base plate (system board) Lead frame * Conventional test vehicle with new material option can be considered as project test vehicle on the basis of members assembly support Heat spreader TV2* : Novel Dual side cooling Power Discrete Heat spreader IGBT Heat spreader
Design Optimization and Reliability Prediction for Power Module/Discrete with Dual Side Cooling Structural modeling and interconnection life prediction for novel dual side cooling power module Power source/gate/drain RDL design optimization for stress minimization Interconnection fatigue life prediction (plastic constitutive model for Cu RDL) Packaging material properties effect on the investigation Electro-thermo-mechanical coupled power cycling impact modeling Thermal modeling and characterization Thermal resistance modeling for selected material set and design Experimental Thermal resistance Rth jc characterization Liquid based active cooling investigation Page 6 Ref. Hua Lua et al. Lifetime Prediction for Power Electronics Module Substrate Mount-down Solder Interconnect Proceedings of HDP 07 Ref. Institute of Microelectronics Dual side cooling effect T jmax decreased compared with single side cooling
High Temperature Endurable Materials for Power Module with T jmax > 220 o C High Temperature Power Device interconnection development High temperature endurable die attach (drain) Micro/Nano Ag sintering (pressure less) TLP bonding : Cu-Sn(415 o C), Ag-Sn(480 o C) Direct Cu-Cu ultrasonic bonding Device backside metallization Substrate surface finish option (Ni/Au finish, ENIG) Power source and gate interconnect through Electrolytic Cu Patterning Ref. Institute of Microelectronics Micro Ag particles sintered by pressure less process TLP bonding (Cu-Sn) used in Infineon XT modules in 2010 High Temperature Endurable Compounds Development High glass transition temperature (T g >200 o C) High thermal conductive compounds (~3W/m-K ) Compatible with Wafer level fan-out process Investigation on thermal degradation (< 3%wt) with continuous exposure to 220 o C Low stress, low thermal mismatch Page 7 Chin-Lung Chiang et.al Thermal stability and degradation kinetics of novel organic/inorganic epoxy hybrid Thermochimica Acta 453 (2007) thermal degradation kinetics for epoxy
High Temperature Endurable Materials for Power Module with T jmax > 220 o C Thermal Interface Material investigation High conductive /temperature endurable Metallic TIM (Ag sintering) with high power insulation layer (Al 2 O 3 ) Polymeric TIM with conductivity > 4W/m-K Thickness control Thermal performance consistency investigation after reliability test High Temperature Endurable Dielectric passivation layer High glass transition temperature (T g >200 o C) BCB, Polyimide photo sensitive PR Compatible with Wafer level fan-out process Investigation on thermal degradation (< 3%wt) with continuous exposure to 220 o C Low stress, low thermal mismatch Source : Danfoss Ag sintering for TIM TIM layer crack propagation Source : Danfoss Page 8
Dual Side Cooling Power Module Process Optimization and Reliability Assessment Dual side Cooling Power Module Assembly Process development Cu clip (Ag plated) attachment / alignment Evaluation of molding material Liquid, Granular Process condition (Temperature, time, pressure) Module shift analysis & control Die/ module pick & place tolerance Minimum clearance between die Warpage control Heat spreader attach and TIM process IME s Novel Dual side Cooling Power Module Assembly Process Reliability Assessments for High Power Application Temperature cycling (Test condition : TBD* 1 ) High Temperature Storage ( 220 o C/ 1000 hrs ) HAST (non-biased) Power Cycling test (optional* 2 ) Failure analysis Tilo Poller et al. Influence of thermal cross-couplings on power cycling lifetime of IGBT power modules CIPS 2102 Power cycling : IGBT with 300W,10Hz Page 9 *1 To be finalized with members input *2 Need member s support on actual SiC wafer and testing
Page 10 Thermal and Structural optimization and life prediction for novel dual side cooling power module Interconnection fatigue life prediction (plastic constitutive model for Cu RDL) Packaging material properties effect on the test vehicle Thermal modeling characterization for selected material set and test vehicles Electro-thermo-mechanical coupled power cycling impact analysis T jmax >220 o C : High Temperature Endurable Power Device Packaging material Solutions (interconnect/encapsulation/tim) High temperature endurable die attach material characterization using Micro/Nano Ag sintering, TLP bonding, Direct Cu-Cu ultrasonic bonding Power source and gate interconnect through Electrolytic Cu Patterning Wafer level Fan-out compatible compounds characterization TIM process optimization for dual side application Dual side Cooling Power Module Assembly Process development Copper clip (Ag plated) attachment / alignment Mold Process condition optimization (Temperature, time, pressure) Heat spreader attach and TIM process Reliability Assessments & F/A for Novel High Power Module Temperature cycling High Temperature Storage / Low Temperature Storage HAST (non-biased) Power Cycling test (optional) Failure analysis * To be finalized Possible Research Outcome*
Members Inputs Project Flow Finalize Project scope and test vehicles specifications Identify high thermal endurable materials and evaluation (Members to provide inputs) Scope Planning Material investigation Process and assembly Modeling & characterization Final reliability Thermal Modeling & Simulation Analysis Mechanical Modeling & Simulation Analysis on stress and reliability Initial Material evaluation and quick reliability test TV1,2 Dual cooling effect Power cycling modeling Electro-Thermo-mechanical Test methodologies (Thermal and Reliability ) Power module EWLP Assembly process optimization. Device chip* (fabrication/purchase) EWLP process modeling flow/warpage TV1 Thermal performance sample matrix TV2 Thermal performance sample matrix TV2 Reliability test sample matrix TV1 Reliability test sample matrix Note: * Electric testing will be carried out based on device chip availability Project Time line and schedule : Nov 2012 to June 2014 Page 11 Thermal performance testing Dual side cooling effect analysis with active cooling Reliability testing Failure analysis and report writing
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