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Substrate Design to Facilitate Backside Heat Sink Attach

IP.com Disclosure Number: IPCOM000009967D
Publication Date: 2002-Oct-02
Document File: 3 page(s) / 116K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to create a substrate to enable the application of a backside heat sink. Benefits include easy attachment and effective heat transfer.

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Substrate Design to Facilitate Backside Heat Sink Attach

Disclosed is a method to create a substrate to enable the application of a backside heat sink. Benefits include easy attachment and effective heat transfer.

Background

Currently, most Low Density Interconnect (LDI) substrates and packages have not required a heat sink; however, in situations where a heat sink is required, it is typically placed on top of the silicon where the heat is generated. New package designs require the top of the silicon to be free, and these designs generate enough heat so that a heat sink is required. The disclosed method effectively transfers heat from these new designs while keeping the silicon free.

General Description

During substrate manufacturing, an area on the backside of the substrate is intentionally left open during soldermask application.� This opening exposes a solid copper plane that is conducive to heat transfer from front-side of the substrate through thermal vias to the solid copper plane.� This exposed area is then available for backside heat sink attach directly to the surface of the copper.

After package assembly, the heat sink can be attached in one of two ways:

 

  1. Thermal interface material is applied to the cavity in the backside of the substrate, then the heat sink is attached.
  2. Thermal interface material is pre-applied on the heat sink, then it is attached to
    the substrate.

Figures 1 through 4 show how the disclosed method is attached.

Advantages

The disclosed method attac...