SubAmbient Heat Sink Concept

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Sub-Ambient Heat Sink Concept
High Pressure Gas In
Vacuum Jacketed Enclosure
Cold Gas Return
Recuperative Heat Exchanger
Low Pressure Gas out
Precooled Gas
2-Phase Mist After Expansion
Thin Film Evaporation
Compliant Sealing for Protecting
Chip/Substrate from Outside Ambient (Expanded
PTFE e.g.)
Compliant Thermal Interface Pad Between Spreader
Plate and Chip
FR-4 Substrate
Chip to Substrate Interconnect

• Key Attributes of the Concept
• High temperature gas input to computer
• cabinet and sub-ambient heat sink.
• Condensation prevention by complete
• enclosure of sub-ambient region.
• Thin film evaporation for maximizing heat flux.

• Key Challenges in Implementation
• Thermal stresses due to large thermal gradient
• between the chip and substrate (compliant chip
  
• to substrate interconnect desirable).
• Need for compliant thermal interface material
• between spreader plate and chip near cryogenic
• temperature.