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Method for a thermal interface for high-power burn-in systems

IP.com Disclosure Number: IPCOM000010798D
Publication Date: 2003-Jan-22
Document File: 7 page(s) / 165K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a thermal interface for high-power burn-in systems. Benefits include improved thermal performance, improved reliability, improved production, and improved ease of manufacturing.

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Method for a thermal interface for high-power burn-in systems

Disclosed is a method for a thermal interface for high-power burn-in systems. Benefits include improved thermal performance, improved reliability, improved production, and improved ease of manufacturing.

Background

              Three key problem areas exist for the conventional process of record (POR) two-phase alloy thermal interface (see Figure 1):

•             Alloy degradation

•             Alloy refurbishment

•             Alloy thermal performance

              Next generation burn-in (NGBI) heatsink assemblies are limited to 350 useful cycles due to the thermal degradation of the alloy. The starting thickness is ~35 microns; the ending thickness is ~5 microns. This thinning results in decreased thermal performance of the heatsink assembly, which is not thermally stable due to varying thermal resistance.

              The alloy is susceptible to oxidation that promotes flaking between the heatsink assembly and the package’s integrated heat spreader (IHS). Flaking leads to potential yield loss due to sticking and decreased thermal performance due to thermal instability from varying thermal resistance.

              Burn-in times increase due to the time required for the alloy’s phase change. NGBI burn-in chambers are capacity constrained, resulting in equipment availability issues.

              Alloy refurbishment/maintenance cost is expensive.

              Several alternative methods are under investigation with the intent of decreasing the cost and improving the performance of the conventional POR two-phase alloy. The top candidates are:

•             Alloy retention: Reduced pressure on the thermal interface may lead to more alloy retention
on the heatsink assembly. This solution may lead to less variance in thermal resistance, which may improve heatsink assembly thermal performance. A higher viscosity alloy may lead to lower oxidation rates, which might result in less sticking and more stable thermal resistance, ultimately resulting in less yield loss and improved thermal performance.

•             Cold engage: Reduced “squeezing out” of alloy during the preconditioning phase may lead to lower oxidation rates. This solution might result in less sticking and more stable thermal resistance, ultimately resulting in less yield loss and improved thermal performance.

General description

              The disclosed method is a thermal interface for high-power burn-in systems. Thermal foil is an alternative thermal interface material (TIM). It is mechanically fastened and aligned to high-power burn-in system heatsink assemblies. Other retention methods are eliminated, such as adhesives that are not as robust or have been shown to detrimentally impact thermal performance. The disclosed method is low cost and easily replaceable in high-volume manufacturing (HVM).

Advantages

              The disclosed method provides advantages, including:

•             Improved thermal performance due to improved thermal stabilit...