Browse Prior Art Database

Thermal Enhancement Technique for Plastic IC Packages

IP.com Disclosure Number: IPCOM000109456D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 65K

Publishing Venue

IBM

Related People

Blackshear, E: AUTHOR [+6]

Abstract

Disclosed is a technique whereby temperature-sensitive plastic IC devices can be solder reflowed using infrared reflow. Plastic IC devices with large silicon chips typically must either be manual attached, or have the maximum reflow temperature constrained to a low value. This is done to avoid package cracking due to pressure created by the outgassing of the water vapor if the device is heated rapidly to a high temperature.

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This is the abbreviated version, containing approximately 83% of the total text.

Thermal Enhancement Technique for Plastic IC Packages

      Disclosed is a technique whereby temperature-sensitive plastic
IC devices can be solder reflowed using infrared reflow.  Plastic IC
devices with large silicon chips typically must either be manual
attached, or have the maximum reflow temperature constrained to a low
value.  This is done to avoid package cracking due to pressure
created by the outgassing of the water vapor if the device is heated
rapidly to a high temperature.

      The disclosed technique (see Figure) consists of various heat
sink attachment methods, using heat staking plastics to provide the
mechanical joining of the heat sink to the plastic surface mount
device, and a suitable thermal management material to provide a
thermally conductive path. For additional thermal enhancement, the
interface between the heat sink and plastic package could be filled
with any suitable thermally conductive material, such as thermal
tape, thermal grease, or thermal epoxy, could be used.  The heat
stakes that mechanically join the heat sink to the IC device could
either be incorporated into the plastic molding of the SMT device, or
be a separate molded stake, which could then be hot upset into a
cavity molded into the plastic package.  If they are incorporated
into the plastic molding of the part, then the process would involve
application of the thermal enhancement material, if required,
placement of the heat sink onto the stakes, followed by hot upsett...