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Method for a heatsink with a recessed contact surface for improved material/HS integration and performance

IP.com Disclosure Number: IPCOM000012347D
Publication Date: 2003-Apr-30
Document File: 4 page(s) / 82K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a heatsink (HS) with a recessed contact surface for improved material/HS integration and performance. Benefits include improved thermal performance and improved ease of manufacturing.

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Method for a heatsink with a recessed contact surface for improved material/HS integration and performance

Disclosed is a method for a heatsink (HS) with a recessed contact surface for improved material/HS integration and performance. Benefits include improved thermal performance and improved ease of manufacturing.

Background

� � � � � The thermal performance of second-level thermal interface material (TIM) and the heatsink is typically limited by contact resistance. A heavy clip force is conventionally used to reduce the interfacial contact resistance. Improved TIMs are continually being investigated to improve thermal performance. Reliability testing is used to verify the level of thermal performance.

        � � � � � Conventional heatsinks have flat surfaces.

        � � � � � Conventionally, cured TIMs, such as elastomeric pads, are applied on a flat surface and held in place by clips that compress the HS. Minimizing contact resistance requires a significant amount of clip force, leading to other issues such as solder joint reliability (SJR) failures on the board level interconnects, load relaxation and board creep over time, and high clip cost.

        � � � � � Uncured TIM systems, such as phase change material and greases, do not require as high a clip force as cured elastomers and provide low interfacial contact resistance by physical wetting forces. These systems, however, tend to migrate during reliability testing and over time, leading to degradation of the heat removal capability.

� � � � � Curable TIMs are typically more reliable than grease and phase-change material (PCM) under thermal stresses. However, they have higher thermal resistance due to high contact resistance, especially in the case of elastomeric pads.

General description

� � � � � The disclosed method includes a heatsink design that improves the integration of TIM with a heatsink. The HS has a recessed contact surface where the TIM is placed. The method directly forms curable TIM on the recessed surface of heatsink, leading to a significant reduction in contact resistance.

� � � � � The TIM can be filled or screen printed into the HS cavity, and then cured. In applications where non-curable materials are required, this cavity could reduce TIM migration and/or pump-out over time and provide bett...