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Preventing Hot Spot Deposits in Liquid Cooled Semiconductor Device Packages

IP.com Disclosure Number: IPCOM000086455D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gregor, LV: AUTHOR [+2]

Abstract

In semiconductor packages employing a liquid coolant, the devices generate significant amounts of heat during operation. When the devices are solder bonded to the substrate, the devices are spaced from the substrate. Since the devices are on the bottom side adjacent the substrate, the major portion of the heat generated occurs at this region. The generated heat causes a localized boiling which in use causes the deposition of any contaminants within the liquid to occur. Contamination presents corrosion and reliability problems.

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Preventing Hot Spot Deposits in Liquid Cooled Semiconductor Device Packages

In semiconductor packages employing a liquid coolant, the devices generate significant amounts of heat during operation. When the devices are solder bonded to the substrate, the devices are spaced from the substrate. Since the devices are on the bottom side adjacent the substrate, the major portion of the heat generated occurs at this region. The generated heat causes a localized boiling which in use causes the deposition of any contaminants within the liquid to occur. Contamination presents corrosion and reliability problems.

In this technique, waxes having very limited solubility in the coolant, typically fluorocarbon liquids are flowed underneath the device to prevent coolant from contacting the device areas. Wax will readily flow underneath the chip and cover the designated areas without withdrawing. Because of the low modulus of these systems, the solder structure reliability will not be affected. Solubility in specific hydrocarbon solvents will allow the easy removal of these waxes for rework of the devices should this be necessary.

Waxes suitable for the purpose include paraffin wax, microcrystalline wax, and other commercially available waxes. In addition to the prevention of hot-spot deposits, the waxes will prevent corrosion from taking place, due to the complete coverage of the solder joints. The amount dispensed usually is of the order of
0.001 gram which readily covers the ar...