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Attachment of Silicon Devices to a Thermal Carrier by Surface Mount Technology

IP.com Disclosure Number: IPCOM000121167D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 60K

Publishing Venue

IBM

Related People

Johnston, C: AUTHOR [+4]

Abstract

The switching power supply program required a low resistance thermal and an electrical path for a vendor power chip to a copper plane on an epoxy card/board. Typically, the chip would be attached to a substrate with a conductive epoxy and then wire bonded for chip I/O's.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Attachment of Silicon Devices to a Thermal Carrier by Surface Mount
Technology

      The switching power supply program required a low resistance
thermal and an electrical path for a vendor power chip to a copper
plane on an epoxy card/board.  Typically, the chip would be attached
to a substrate with a conductive epoxy and then wire bonded for chip
I/O's.

      This disclosure describes the use of surface mount technology
to attach the chip by reflowing 63/37 (Sn/Pb) solder paste at the
same time when other components are attached to the card.  Back
bonding of chip with solder paste is not exercised anywhere.  The
back bonding of chip using a conductive epoxy requires additional
cure time and the electrical as well as thermal resistance are much
higher than solder connection.  The back side of the chip is
metallized to provide electrical connection to the card through
solder joint.

      The above attachment process has been demonstrated as reliable
means of attaching chip on board and is also shown to meet the
product requirements from electrical, thermal and manufacturability
standpoints.  The paste is screened on the board for all components
including the chip.  The chip and other components are joined to the
card/board by a vapor phase or an I/R reflow process.  The process is
developed and implemented into manufacturing.  The backside
metallization on the chip has gold as a top layer to provide
oxide-free reliable solder joint.  Further, the join...