Browse Prior Art Database

Thermal Enhancement of A-Wire

IP.com Disclosure Number: IPCOM000103264D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Ward, W: AUTHOR

Abstract

A method is disclosed for enhancing the thermal efficiency of A-wire (lead frame laminated to chip face) packaging structures for semiconductor memory chips.

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Thermal Enhancement of A-Wire

      A method is disclosed for enhancing the thermal efficiency of
A-wire (lead frame laminated to chip face) packaging structures for
semiconductor memory chips.

      A double side adhesive (butyl-phenolic) on two mil Kapton H
film is used in A-wire structures to laminate the lead frame to a
semiconductor chip. The adhesive is 0.0008" on each side and, upon
lamination, the lead frame sinks into the full depth of the adhesive
while the adhesive between the Kapton film and chip is not displaced.
Thus, the resultant thickness of the film and adhesive is 2.8 mils
thick which exceeds the alpha barrier threshold by 1.2 mils.

      By reducing the Kapton thickness and utilizing a thermally
conductive compound (aluminum nitride) which is alpha free as a
Kapton filler, the film is be thermally enhanced. A thickness
reduction of 50% in the Kapton film results in a 1 degree/watt
reduction in internal thermal resistance. Further, the addition of a
thermally conductive medium to the Kapton (which is alpha free)
results in a 2 degree/watt additional reduction. The actual film
conductivity is enhanced from .118watt/meter/degree Kelvin to
.42watt/meter/degree Kelvin.

      The filled Kapton film offers reduce acoustic damping which
enhances the second (wedge) wire bond. Thinning of Kapton offers more
reliability and repeatability of the second wire bond.

      Disclosed anonymously.