Browse Prior Art Database

Enhanced IR Reflow Process using Reflective Caps

IP.com Disclosure Number: IPCOM000107939D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Hebert, TM: AUTHOR [+4]

Abstract

Infrared (IR) reflow of surface mount components (SMCs) is a well known art. While the technique also works successfully for soldering C4 chips to glass-epoxy substrates, simultaneous reflow of a panel comprised of a variety of SMCs and C4 silicon chips is not always feasible. For example, certain products permit only one reflow for SMC devices and some pin-in-hole (PIH) modules have an upper temperature limit. This necessitates thermal shielding of these sensitive components during the reflow cycle for attachment of C4 chips. Often the thermal shields create a shadowing effect that results in poor reflow joining of the C4 chips. In this disclosure, the authors suggest the use of reflective metallized polymeric caps for placement over the thermally sensitive components.

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Enhanced IR Reflow Process using Reflective Caps

      Infrared (IR) reflow of surface mount components (SMCs) is a
well known art.  While the technique also works successfully for
soldering C4 chips to glass-epoxy substrates, simultaneous reflow of
a panel comprised of a variety of SMCs and C4 silicon chips is not
always feasible.  For example, certain products permit only one
reflow for SMC devices and some pin-in-hole (PIH) modules have an
upper temperature limit.  This necessitates thermal shielding of
these sensitive components during the reflow cycle for attachment of
C4 chips.  Often the thermal shields create a shadowing effect that
results in poor reflow joining of the C4 chips.  In this disclosure,
the authors suggest the use of reflective metallized polymeric caps
for placement over the thermally sensitive components.  These caps,
while providing thermal insulation to the components that they cover,
reflect part of the IR radiation into the shadow region, thereby
enhancing the reflow of the chips.

      Laboratory verification experiments were performed to support
the claims.  The data shows that in order to enhance the reflow of
chips in the shadow region caused by thermal shields it is beneficial
to use reflective caps.

      It is recommended that either Dow Corning's Silastic E
(trademark) with aluminized tape or any high temperature
thermoset/thermoplastic polymer with a sputtered aluminum exterior
coating be used for this purpose.

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