TECHNIQUE FOR COOLING WAFERS DURING PbSn EVAPORATION
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
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.