Browse Prior Art Database

Dispensing Flux Paste in Ball Grid Array Assembly

IP.com Disclosure Number: IPCOM000118253D
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Colombo, EC: AUTHOR [+2]

Abstract

In Ball Grid Array (BGA) packaging, the leads on the periphery of a conventional package are replaced by a grid of balls on a surface of the package. In this way, the entire surface of the package is available for electrical connections, significantly increasing the packing density.

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Dispensing Flux Paste in Ball Grid Array Assembly

      In Ball Grid Array (BGA) packaging, the leads on the periphery
of a conventional package are replaced by a grid of balls on a
surface of the package.  In this way, the entire surface of the
package is available for electrical connections, significantly
increasing the packing density.

      A BGA package is composed of a substrate material on one side,
of which one or more chips are attached, and electrically connected
with the substrate itself and, on the opposite side or even on the
same side, a grid of solderable lands is electrically connected with
the chip.  The substrate can be organic material (epoxy-glass or
polymide) or ceramic material.  The chip can be connected using flap
chip technology or wire bonding technology.

      The BGA package is itself mounted on a circuit board by means
of solder connection balls.  To allow the balls to be kept in place
during the time frame between the placement and the reflow, a tacky
flux paste is used.  This paste is conventionally applied by picking
up the balls with a vacuum tool, dipping them into a flux pot and
placing them on the substrate.  The dipping of balls into the flux is
very critical because the paste can easily splash and the quantity of
flux that remains on the balls is neither precise nor repeatable.

      The technique described permits a precise and repeatable
quantity of flux to be dispensed.

      Referring to the Figure, the...