Browse Prior Art Database

Technique for Aiding Reworkability of Encapsulated Semiconductors

IP.com Disclosure Number: IPCOM000115180D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Ameen, JG: AUTHOR [+3]

Abstract

Reworkability of encapsulated semiconductors packages is achieved by pre-coating the surfaces of the package and the carrier with a thin layer of thermoplastic polymer. The thermoplastic polymer can be dispensed as a solvent thinned liquid, which will readily conform to the geometrical features of the package. After oven drying to remove the solvent, the package is encapsulated in the normal manner with a conventional thermosetting encapsulant. The thermoplastic is chosen to provide good adhesion to the package and the board, and to be insoluble in the uncured epoxy resin of the encapsulant. To achieve rework, the encapsulated package is heated, causing the solder and the thermoplastic to soften.

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Technique for Aiding Reworkability of Encapsulated Semiconductors

      Reworkability of encapsulated semiconductors packages is
achieved by pre-coating the surfaces of the package and the carrier
with a thin layer of thermoplastic polymer.  The thermoplastic
polymer can be dispensed as a solvent thinned liquid, which will
readily conform to the geometrical features of the package.  After
oven drying to remove the solvent, the package is encapsulated in the
normal manner with a conventional thermosetting encapsulant.  The
thermoplastic is chosen to provide good adhesion to the package and
the board, and to be insoluble in the uncured epoxy resin of the
encapsulant.  To achieve rework, the encapsulated package is heated,
causing the solder and the thermoplastic to soften.  This allows the
removal of the package from the carrier by applying some mechanical
force without damage to either the package or the carrier.  Any
residue of the thermoplastic can be removed with solvent.