Surface Mount Heat Sink for Solder Ball Connect Modules and C4 Chip to Card Attach

Surface Mount Heat Sink for Solder Ball Connect Modules and C4 Chip
to Card Attach

      Disclosed here is a heat sink that has a minimum of four
mounting posts one at each corner, and possibly additional mounting
posts on the sides, that is suitable for surface mount soldering to a
printed circuit carrier, using standard solder paste and Infrared
reflow processes.  A thermal grease or other suitable thermal
coupling agent, applied between the Solder Ball Connect (SBC) carrier
and the heat sink, ensures the required heat transfer between the
chip and the heat sink.  Once the heat sink is attached, soldering
the mounting posts to the carrier stiffens the carrier within the
area of the SBC chip and thereby deflects and/or transfers the
mechanical energy away from the solder ball interface region.
Subordinately, the heat sink is supported and mounted to the S1 layer
of a carrier, not to the SBC chip.  This further reduces strain on
the solder ball interface region under conditions of stress and
eliminates mounting materials used to assemble the heat sink to an
SBC chip.  Additionally, physical designers can use the layers under
the heat sink mounting posts because of the surface mount feature.
If the surface mount pads where the heat sink attaches are attached
to the carrier ground, the heat sink is grounded, eliminating
radiation of Radio Frequency (RF) energy by the heat sink, the heat
sink thus becomes an Electromagnetic Interference (EMI) shield for
the SBC chip.

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