Browse Prior Art Database

Apparatus for Solder Ball Alignment and Containment

IP.com Disclosure Number: IPCOM000117049D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Downes Jr, FJ: AUTHOR [+3]

Abstract

Disclosed is an alignment and containment device to be used with a pattern of bumps on chips and modules, i.e., C4s on chips, solder balls on BGA. The apparatus used is composed of a dielectric material with a pattern of holes. Hole pattern is the same and slightly larger in diameter than the bumps on the applicable component. Larger diameter holes provide a simple aid in alignment during component placement. When the assembly requires a constant load be applied to the component as in a temporary attach application using dendritic pads on the carrier, solder bumps will deform and/or creep to a larger diameter. By controlling the hole size in the dielectric material the bumps can be contained within the hole diameter.

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This is the abbreviated version, containing approximately 88% of the total text.

Apparatus for Solder Ball Alignment and Containment

      Disclosed is an alignment and containment device to be used
with a pattern of bumps on chips and modules, i.e., C4s on chips,
solder balls on BGA.   The apparatus used is composed of a dielectric
material with a pattern of holes.  Hole pattern is the same and
slightly larger in diameter than the bumps on the applicable
component.  Larger diameter holes provide a simple aid in alignment
during component placement.  When the assembly requires a constant
load be applied to the component as in a temporary attach application
using dendritic pads on the carrier, solder bumps will deform and/or
creep to a larger diameter.  By controlling the hole size in the
dielectric material the bumps can be contained within the hole
diameter.

      Thickness of the dielectric must be less than the height of the
bumps.  This thickness design serves to control the collapse of the
bumps during prolonged compression loading on the component of solder
reflow.  For any application where the solder does require reflow,
the dielectric must be able to withstand the solder reflow
temperatures.  Additional holes can be included outside of the
pattern for location and mounting to the component carrier.

      In the case where an extensive temporary attachment is
maintained and the bumps expand to fill the hole, the dielectric will
become attached to the component.  Removal of the dielectric from the
component after disassemb...