Browse Prior Art Database

Fast Gelling of Epoxy Chip Encapsulant Materials

IP.com Disclosure Number: IPCOM000111485D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Wood, JC: AUTHOR

Abstract

Disclosed is a manufacturing enhancement in the process of epoxy encapulating wire bonded silicon chips onto circuits (e.g., flexible circuits), to prevent the ingress of local atmospheric water. By employing a tungsten-halogen filament lamp radiation in place of infrared conventional ovens, a rapid skin is formed on epoxy deposits, permitting easier handling and faster curing.

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Fast Gelling of Epoxy Chip Encapsulant Materials

      Disclosed is a manufacturing enhancement in the process of
epoxy encapulating wire bonded silicon chips onto circuits (e.g.,
flexible circuits), to prevent the ingress of local atmospheric
water.  By employing a tungsten-halogen filament lamp radiation in
place of infrared conventional ovens, a rapid skin is formed on epoxy
deposits, permitting easier handling and faster curing.

      Epoxy encapsulants are dispensed to encapsulate chips in tape
automatic bonding products and in applications such as flexible
circuit cables in compact disk files.  They are difficult to use
because they are moisture sensitive until cured or gelled (skinned).
They also can flow prior to cure onto undesired places; they are
sometimes required to be dispensed onto circuits standing on hot
surfaces or may require to be mechanically stabilised by full or
partial oven cure before inspection and touch-up can be applied.  All
these difficulties are traditionally solved by thermal methods
involving ovens, heated plattens and fast transit from process to
cure oven.  These are well-tested approaches, but because of slow
heat transfer, they can take up to four hours to cure prior to
inspection, rework and a further four-hour cure period.  Some flex
circuit structures are thermally well insulated, which makes platten
heating extremely difficult.  The solution proposed is that all of
the processes described above can be improved by the use of low
wattage tungsten-halogen reflector bulbs, with considerable reduction
in process time and equipment complexity.  These bulbs emit in the
ultraviolet, visible and infrared regions of the spectrum.  All these
w...