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Method for Mechanically Pinning an IC Package Heat Spreader to a Substrate

IP.com Disclosure Number: IPCOM000011730D
Publication Date: 2003-Mar-12
Document File: 5 page(s) / 273K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for mechanically pinning an integrated circuit (IC) package heat spreader to a substrate. Benefits include improved performance, reliability, throughput, ease of manufacturing, and design flexibility.

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Method for Mechanically Pinning an IC Package Heat Spreader to a Substrate

Disclosed is a method for mechanically pinning an integrated circuit (IC) package heat spreader to a substrate. Benefits include improved performance, reliability, throughput, ease of manufacturing, and design flexibility.

Background

              Conventionally, the integrated heat spreader (IHS) assembly (see Figure 1) process is complex with a low utilization rate due to the large number of process steps.

General description

              The disclosed method is attaching an IHS to an IC package substrate using mechanical pinning. The pin feature can be attached using through-holes, solder/epoxy, or press fitting techniques.

              The key elements of the method include:

•            Pin features that are used to mechanically bond the substrate and the IHS

•            Spring-loaded retention mechanisms that hold the edge of the IHS and push it down on the die to maintain the heat spreader location in reference to the die

Advantages

              The disclosed method provides advantages, including:

•             Improved performance due to improved alignment of the IHS in relation to the die because of the use of pinning features

•             Improved reliability due to preventing sealant delamination because of the use of clips

•             Improved reliability due to stiffer substrate-to-package interconnection because of eliminating sealant delamination and the reduction of tensile stress on TIM

•             Improved throughput due to eliminating four processing steps

•             Improved throughput due to eliminating yield loss from sealant stringers and heat spreader placement

•             Improved ease of manufacturing due to eliminating four processing steps

•             Improved design flexibility due to reducing the number of features because of the elimination of the sealant lip and bleedhole

•             Improved cost effectiveness due to eliminating four processing steps

Detailed description

              The disclosed method is attaching an IHS to an IC package substrate using mechanical pinning. The basic mechanical aspects of a conventional flip-chip CPU package with an IHS are maintained. A rigid IHS is adhered to a flip-chip CPU package with a die-referenced stack up. Pin features ensure the IHS aligns with the substrate. The bond line thickness (BLT) of the thermal interface material (TIM) is minimized by spring forces on the pins at the attachment location of the IHS to the substrate. The load of the spring-loaded clips is design...