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TECHNIQUE FOR COOLING WAFERS DURING PbSn EVAPORATION

IP.com Disclosure Number: IPCOM000047566D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Crnic, F: AUTHOR [+3]

Abstract

A liquid-cooled heat sink is used during lead-tin (PbSn) evaporation through a molybdenum mask onto silicon wafers. The heat sink 10 can be made of aluminum. The liquid container 12 contains a suitable fluorocarbon liquid having a boiling point of about 56ŒC. As the wafer mask assembly heats up, due to the radiant heat from the PbSn solder evaporation source, the liquid in the heat sink will also heat up and start to boil at 56ŒC. A cooling fin arrangement 14 is located on the surface of the liquid container opposite to the surface 16 of the heat sink 10 that is fitted into the mask assembly.

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TECHNIQUE FOR COOLING WAFERS DURING PbSn EVAPORATION

A liquid-cooled heat sink is used during lead-tin (PbSn) evaporation through a molybdenum mask onto silicon wafers. The heat sink 10 can be made of aluminum. The liquid container 12 contains a suitable fluorocarbon liquid having a boiling point of about 56OEC.

As the wafer mask assembly heats up, due to the radiant heat from the PbSn solder evaporation source, the liquid in the heat sink will also heat up and start to boil at 56OEC. A cooling fin arrangement 14 is located on the surface of the liquid container opposite to the surface 16 of the heat sink 10 that is fitted into the mask assembly.

As liquid boiling starts to occur in the liquid region 12 close to the source of the heat at surface 16, cooling of the wafer/mask assembly occurs due to this nucleate boiling phenomenon and heat gets conveyed from the wafer/mask to the liquid boiling region to the colder liquid regions. Thus, the temperature of the wafer can be maintained at the relatively low temperature of the boiling point of the liquid.

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