Heat-transfer microstructures for integrated circuits

Technical Report · Wed Feb 01 00:00:00 EST 1984

OSTI ID:5215635

Tuckerman, D B

Convective heat-transfer theory indicates that well over 1000 W/cm/sup 2/ can be compactly removed from ICs at normal operating temperatures, provided microscopic (e.g., 50-..mu..m wide) extended-surface structures are used. The difficulty of constructing high-conductance, low-stress thermal interfaces between ICs and heat sinks suggests the use of an integral heat sink. Accordingly, IC microfabrication techniques were employed to design, fabricate, and test novel, ultracompact water-cooled, laminar-flow, optimized plate-fin and pin-fin heat sinks directly within standard-thickness silicon substrates. Worst-case thermal resistances as low as 0.083/sup 0/C/W were measured from 1-cm/sup 2/ thin-film resistors. The use of integral liquid-cooled heat sinks in multichip systems presents potential yield, reliability, cost and packaging problems. Attachment of unmodified ICs to micro-heat sinks seems a more attractive approach. A novel die-attachment technique has been developed which avoids the problems of conventional attachments. In this technique, a liquid partially fills an array of micron-wide reentrant capillaries in the heat sink substrate, so that surface tension holds the polished back of an IC in intimate thermal contact with the heat sink. The bond is void-free, virtually stress-free, long-lived, and allows repeated detachment and replacement of ICs without damaging the heat sink substrate. The reentrant grooves were fabricated by a noval process using electroless plating of nickel onto vertical silicon microgrooves. For a 1-cm/sup 2/ area, typical interfacial thermal resistances of 0.022/sup 0/C/W at 300 W have been measured. In summary, microfabrication techniques have been employed to fabricate new, very high-performance liquid-cooled heat sinks having negligible volume (0.1 cm/sup 3/), and also to make a novel, stress-free, reusable microcapillary thermal interface between such heat sinks and integrated circuit substrates.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5215635
• Report Number(s): UCRL-53515; ON: DE84009137
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
INTEGRATED CIRCUITS
HEAT SINKS
DESIGN
FABRICATION
FINS
PLATES
SILICON
TESTING
THERMAL CONDUCTIVITY
WATER
ELECTRONIC CIRCUITS
ELEMENTS
HYDROGEN COMPOUNDS
MICROELECTRONIC CIRCUITS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SEMIMETALS
SINKS
THERMODYNAMIC PROPERTIES
420800* - Engineering- Electronic Circuits & Devices- (-1989)