MICROSTRUCTURES FOR HEAT TRANSFER IN STIRLING MICRO-REFRIGERATORS

SUNPOWER PROPOSES TO DESIGN MICROSTRUCTURES FOR HEAT TRANSFER IN NOVEL STIRLING MICROREFRIGERATORS INSIDE MULTI-CHIP MODULE PACKAGES FOR REMOVING HEAT AT LOW TEMPERATURES FROM WAFER SCALE INTEGRATED CIRCUITS IN SPACE SYSTEMS. THE MICROREFRIGERATOR EXPLOITS THE MATERIAL PROPERTIES, MECHANICAL DESIGNS, TINY DIMENSIONS, AND BATCH FABRICATION PROCESSES OF SILICON MICROMACHINING. IF FEASIBLE, THE MICROREFRIGERATOR WILL ENABLE ELECTRONIC DEVICES BONDED DIRECTLY TO THE SILICON COLD PLATE, OR FABRICATED WITHIN IT, TO BE OPERATED AT TEMPERATURES FROM 250K DOWN TO 60K OR LESS, DEPENDING UPON THE APPLICATION-SPECIFIC DESIGN. ONE PRELIMINARY 1CM3 MICROREFRIGERATOR DESIGN PREDICTS 2.5W OF HEAT LIFTING CAPACITY FROM 225K TO 350K WITH MECHANICAL INPUT POWER OF 2.5W. THE INERTIA OF THE VIBRATING ACTUATOR IN ONLY 10 TO THE -4G. FOR MXN GREATER HEAT LOADS, MXN MICROREFRIGERATORS CAN BE FABRICATED AS A MECHANICALLY INTEGRATED MXN CM2 ARRAY. THE MICROSTRUCTURES TO BE DESIGNED DURING PHASE I INCLUDE HEAT EXCHANGERS, MICRO-HEATPIPES, AND MICRO-TUBES FOR AXIAL THERMAL CONDUCTION ENHANCEMENT. EFFECTS OF THE MICROSTRUCTURES ON THE THERMAL PERFORMANCE OF MICROREFRIGERATORS WILL BE DETERMINED, AND A FEASIBLE HEAT TRANSFER SYSTEM SELECTED FOR FABRICATION IN PHASE II.