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Solder Application Method via Punching of Solder Foil

IP.com Disclosure Number: IPCOM000108123D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Leerssen, A: AUTHOR [+4]

Abstract

The method proposed here involves punching a pattern off a solder foil. The dimensions of the punch and the thickness of the foil are so chosen that a disk of solder of the required solder volume is punched out and placed on the copper pad of the card. The card footprint is prefluxed so that the disk placed on the pad stays in place until the card is mass reflowed. During the mass reflow process, the disk melts and forms a metallurgical bond with the pad and a well formed solder crown. After reflow and cleaning (if required), the presoldered footprint can then be used for component attachment.

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Solder Application Method via Punching of Solder Foil

       The method proposed here involves punching a pattern off
a solder foil.  The dimensions of the punch and the thickness of the
foil are so chosen that a disk of solder of the required solder
volume is punched out and placed on the copper pad of the card.  The
card footprint is prefluxed so that the disk placed on the pad stays
in place until the card is mass reflowed.  During the mass reflow
process, the disk melts and forms a metallurgical bond with the pad
and a well formed solder crown.  After reflow and cleaning (if
required), the presoldered footprint can then be used for component
attachment.

      Shown in the figure is an isometric drawing of the punch
set-up, showing exploded views of critical parts.  The footprint is a
representation of pad site geometrics.  The punch itself has the chip
footprint so that, as the disks are punched out, they will be placed
on individual pads on the cards which have already been fluxed.

      Multiple chip sites can be covered because the concept lends
itself to automation very easily.  The concept is useful in direct
chip attachment (DCA) situations.