Method for an integrated heat spreader with a pre-applied sealant adhesive

Method for an integrated heat spreader with a pre-applied sealant adhesive

Background

Silicon designs increasingly require heat removal by larger and heavier heat sinks. An integrated heat spreader (IHS) is conventionally sealed to a package using the following methods (see Figure 1):

1.      A polymer sealant is dispensed onto the package.

2.      The IHS is picked up, placed, and clipped on top of the package.

3.      The sealant is cured.

              The sealant reduces mechanical loading on the thermal interface material, but the package warps during thermal cycling.  Sealant-dispensing tools reduce overall assembly line utilization and increase assembly cost.

Description

Disclosed is a method for attaching an integrated heat spreader with a pre-applied sealant adhesive. Benefits include reduced dynamic warpage of the package during thermal cycling, reduced stress on the thermal interface, and improved control of sealant placement and flow.  The disclosed method is an IHS with pre-attached B-stage or solder sealant adhesive polymer dispensed on to the surface of the IHS lip for bonding the spreader to the package (see Figure 2). The sealant reduces dynamic warpage of the package during thermal cycling and reduces the stress load on the thermal interface.

Key elements of the disclosed method include:

·        IHS with dispensed B-stage polymer or solder sealant attached to the bottom periphery

Advantages

The IHS with pre-attached dispensed sealant eliminates the requirement for sealant dispensing.  Dispensin...