Browse Prior Art Database

New Coating for Radial Finger Cooling

IP.com Disclosure Number: IPCOM000060854D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Grandguillot, M: AUTHOR [+2]

Abstract

Radial finger cooling (RFC) is used to get a thermal path between the semiconductor chip and the module cap to make easier the flow of heat produced by the chip when it is powered. This thermal parameter must be improved as the chip power increases with density and the speed of modern integrated circuits. RFC is a spring made of copper/zirconium alloy which must satisfy the following requirements: -a good thermal contact between the chip and the spring and between the spring and the cap; -to maintain a force on the chip without destroying the solder pads; -not to alter the packaging characteristics after thermal shocks generated by test, shipping, handling and manufacturing.

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New Coating for Radial Finger Cooling

Radial finger cooling (RFC) is used to get a thermal path between the semiconductor chip and the module cap to make easier the flow of heat produced by the chip when it is powered. This thermal parameter must be improved as the chip power increases with density and the speed of modern integrated circuits. RFC is a spring made of copper/zirconium alloy which must satisfy the following requirements: -a good thermal contact between the chip and the spring and between the spring and the cap; -to maintain a force on the chip without destroying the solder pads; -not to alter the packaging characteristics after thermal shocks generated by test, shipping, handling and manufacturing. It is coated with nickel to provide protection against corrosion; however, if this solution gives good results, it does not permit a low enough thermal resistance for more advanced future products. To improve the module thermal characteristics, a new coating of the spring is proposed. This coating is composed of layers of two different materials: a metallic alloy and a corrosion protector located at very specific locations, as depicted in the drawing.

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The metallic alloy layer acts as an improvement of the thermal path between the two thermal contacts chip/spring and spring/cap. The corrosion protector layer acts as a barrier to limit metallic alloy spreading during the manufacturing reflow step, thus keeping the elasticity of the RFC in or...