Browse Prior Art Database

Solder Cream Laser-Assisted Ultrasonic Reflow Solder Application Method

IP.com Disclosure Number: IPCOM000103413D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 25K

Publishing Venue

IBM

Related People

Porter, R: AUTHOR [+4]

Abstract

Disclosed herein is a method whereby solder paste or cream is stenciled as a continuous pattern covering a set of pads, which may or may not be isolated by solder mask. The card is fixtured in a tool which employs a laser heated ultrasonic bonding tip. Each pad is contacted by this tip sequentially; and by virtue of the synergistic action of thermal energy combined with ultrasonics, reflow of solder on the pad occurs, confining the solder crown to individual pads. As an example, it has been possible to obtain an average solder height of 0.0025" on 0.0087" diameter circular pads for flip chip applications using a Nd:YAG laser emanating 18 millisecond pulses.

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Solder Cream Laser-Assisted Ultrasonic Reflow Solder Application Method

      Disclosed herein is a method whereby solder paste or cream is
stenciled as a continuous pattern covering a set of pads, which may
or may not be isolated by solder mask.  The card is fixtured in a
tool which employs a laser heated ultrasonic bonding tip.  Each pad
is contacted by this tip sequentially; and by virtue of the
synergistic action of thermal energy combined with ultrasonics,
reflow of solder on the pad occurs, confining the solder crown to
individual pads.  As an example, it has been possible to obtain an
average solder height of 0.0025" on 0.0087" diameter circular pads
for flip chip applications using a Nd:YAG laser emanating 18
millisecond pulses.

      Disclosed anonymously.