Browse Prior Art Database

Method for Attach and Repair of Modules using Area Array Solder Interconnect

IP.com Disclosure Number: IPCOM000109474D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Horton, RR: AUTHOR [+3]

Abstract

A current area array attachment technique utilizes spheres containing high percentage Pb with Sn to provide electrical contact with the organic board. These spheres are on an area array across the bottom surface of the module and are held in place with eutectic solder at both the module and board interfaces. At the junction of each interconnect is a via through the organic card to connect interior planes with surface wiring.

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Method for Attach and Repair of Modules using Area Array Solder Interconnect

      A current area array attachment technique utilizes spheres
containing high percentage Pb with Sn to provide electrical contact
with the organic board.  These spheres are on an area array across
the bottom surface of the module and are held in place with eutectic
solder at both the module and board interfaces.  At the junction of
each interconnect is a via through the organic card to connect
interior planes with surface wiring.

      These vias can be used as paths to transport heat necessary for
both module removal and reattach.  Two approaches for supplying heat,
although unrelated, achieve the same result by heating the desired
surface and not the surrounding area or the module itself.  A hot air
thermode (HAT) brought into contact with the board from the opposite
side of the component is pulsed with heated nitrogen for a period of
time necessary to melt the solder at the board/solder sphere
interface.  Alternately, an infrared light source with the
appropriate wavelength is either focused or scanned across the same
area.  This will also apply the heat to the correct surface to be
melted as the FR4 will be transparent to the wavelength while the
copper via conducts the heat through the board.  Reattach is done in
the same manner by employing either heating technique.

      Disclosed anonymously.