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Attachment to an IC Package Using Focused Light or Laser to Instantly Solder the Integral Heat Spreader to the Package

IP.com Disclosure Number: IPCOM000012945D
Publication Date: 2003-Jun-11
Document File: 2 page(s) / 142K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method of attaching an integrated heat spreader (IHS) to an IC package, using highly focused light beams or lasers as a reflow heat source. Benefits include a reduction in process costs, equipment, and steps.

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Attachment to an IC Package Using Focused Light or Laser to Instantly Solder the Integral Heat Spreader to the Package

Disclosed is a method of attaching an integrated heat spreader (IHS) to an IC package, using highly focused light beams or lasers as a reflow heat source. Benefits include a reduction in process costs, equipment, and steps.

Background

Currently, IHS are attached to the package using a multi-step sealant dispense process that also requires a sealant cure process to complete the attachment (see Figure 1). The general processing steps are:

  1. Dispense sealant onto the substrate.
  2. Dispense flux onto the die.
  3. Pick and place a solder preform onto the die.
  4. Dispense flux onto the solder perform.
  5. Place the IHS (a selective plated gold IHS with plating over the die. The IHS is flat, 0-35um) and clip on top of the die to maintain position.
  6. Reflow the thermal interface solder.
  7. Cure the sealant adhesive.
  8. Remove the spring clip.

General Description

In the disclosed method,  the IHS is placed, preloaded, and instantly reflowed to the substrate pads using a focused beam of light, laser, or some other instant heat source. This process eliminates both the equipment and materials required to attach the IHS using dispense type processes. 

A key feature of the dimpled reflow process is that the IHS to substrate attachment is still die referenced (see Figure 2). The dimpled reflow retention mechanism that holds the IHS in place is reflowed after the IHS is positioned and pre-loaded w...