Hi Matt.

21-Sep-03 00:58:34, Matt Mc_Carthy wrote to Wayne Chirnside


 MM> 20 Sep 2003, 10:15, Wayne Chirnside (2:252/171), wrote to Matt
 MM> Mc_carthy:

 MM> Hi Wayne.

 MM>>> Nor have I!  The original Pentium series was a
"PGA", Pin Grid
 MM>>> Array type chip.  A large reddish colored ceramic square with
 MM>>> all the pins under it.  Later they came up with the smaller
 MM>>> black pinless plastic chip intended to be soldered directly onto
 MM>>> MBs, but instead soldered to a small PCB with all the pins on it
 MM>>> to be used in the socket motherboards.  This was (I think) the
 MM>>> "PFPG" chip, Plastic Flat Pinless Grid chip
soldered onto an
 MM>>> adapter board.  What I think you are seeing is the top ends of
 MM>>> all the pins sticking through the adapter PCB.

 WC>> That's what it looks like.

 MM>>> If that is the case, the tops of the pins should be well below
 MM>>> the top of the CPU itself, and a regular heatsink that uses a
 MM>>> flat strap to snap onto the tabs of the socket should work fine.
 MM>>>  The bottoms of the heatsinks are normally anodized, and are
 MM>>> non-conductive, unless the anodizing has been machined off.

 WC>> Well I've never seen a flat strap heatsink retainer either but
 WC>> shall check into a computer build shop for one.

 WC>> I was thinking about a dab thermal compound and a dab of gel
 WC>> super glue around the edge of the thermal contact area. What do
 WC>> you think about this?

 MM> I've not had much luck with super glue on things that heat up, and
 MM> especially things that heat (expand) and cool (shrink).  The Super
 MM> glues are too brittle and crack easily.

I've seen superglue used to glue rubber to rubber with success

 MM> As an afterthought, (I've NOT tried this), some of that "High
 MM> Temp" Silicone sealant from an automotive store might do the job,
 MM> especially if they have a non-conductive version.

Most if not all RTV silicones can withhstand the temperature of a working CPU
although something with an acid cure would probably be unsuitable.

 MM> Put a chocolate
 MM> chip sized 'dab' in each of the four corners of the adapter board
 MM> right over the tops of the pins, put heat sink on with compound,
 MM> Good luck...  M.

yeah, gotta use heatsink compound on the chip - regular silicone doesn't work.

 MM> Any shrinkage as the silicone sets
 MM> would only tighten the heat sink, and with the extra space over
 MM> the pins, a slice with a razor would remove the bond easily if
 MM> ever needed.

should work in that application but I've never seen shrinkage with RTV
silicone

 -=> Bye <=-

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