Browse Prior Art Database

Conductive Bump Formation Process

IP.com Disclosure Number: IPCOM000123431D
Original Publication Date: 1998-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 28K

Publishing Venue

IBM

Related People

Farquhar, DS: AUTHOR [+3]

Abstract

A method for forming an electrical interconnection between device leads and a printed circuit board is disclosed. The connection is formed using an electrically conductive adhesive instead of the more conventional metallurgical bonding using a tin and lead solder alloy. The adhesive is a thermosetting polymer with a highly conductive metal filler. It is selectively applied to the printed circuit board in a pattern corresponding to the electrical contacts on the surfaced of the printed circuit board. This can be accomplished by using conventional methods, such as a screening process. Uncured thermosetting adhesives can be of relatively low viscosity and thus readily screened in a fine pattern.

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Conductive Bump Formation Process

   A method for forming an electrical interconnection between
device leads and a printed circuit board is disclosed.  The
connection is formed using an electrically conductive adhesive
instead of the more conventional metallurgical bonding using a tin
and lead solder alloy.  The adhesive is a thermosetting polymer with
a highly conductive metal filler.  It is selectively applied to the
printed circuit board in a pattern corresponding to the electrical
contacts on the surfaced of the printed circuit board.  This can be
accomplished by using conventional methods, such as a screening
process.  Uncured thermosetting adhesives can be of relatively low
viscosity and thus readily screened in a fine pattern.  After
screening, the viscosity of the adhesive can be increased by
partially advancing its cure by heating it in a controlled way, thus
preventing it from bleeding across the surface of the printed circuit
board.  The next step is to place the electrical device on the
printed circuit board, so that its electrical leads make contact with
the previously screened adhesive.  Finally a nominal pressure is
applied to the device leads and the adhesive is completely cured by
means of heat application.