IRIX on Personal Iris - test-drb@ccmp.vtda.org

8 May 2002

On May 9,  0:28, Tony Duell wrote:

...
  > > To upgrade Indigo 4MB SIMMs, you need to
find eight 514400 (or equivalent)
...
  > > 80ns DRAMs in 26/20-pin SOJ package, and
eight SMD decoupling capacitors
...
  > > (sorry, don't remember the value but
such caps are usually about
 > > 100-200nF).  The capacitors are fitted in positions marked C3, C4, C8,
C9,
...
  > > C12, C13, C17, C18 on the DRAM side, before
the DRAMs (which cover them).
...
  >
 > Sounds easy enough.  Now all I need to do is find someone with an SMD rework
...
  > station.  ^_^  This'd be a good time to see
about upgrading my SPARCBook2 to
...

 For something like this you could probably use a fine-tipped soldering
 iron and fine silver-loaded solder. You'll have to work slowly and
 carefully, but SMD soldering is possible with normal hand tools... 
Indeed it is, and that's what I'd often do, but in this case the DRAMs are
very close together and I don't think it's possible to get even the finest
tip in between, certainly not at the angle needed to get to the pads under
the J-leads.

I used a hot air gun last time -- similar to the type used
for paint stripping or heat-shrink tubing, except that mine is
thermostatically controlled.  Use lots of flux, or tiny amounts of fresh
SMD rework solder paste, keep the board level and firmly supported, and
practice on a scrap item first.

Given the lack of space between the ICs, if you do know someone with a
proper SMD rework station, that would be safer.  It's worth mentioning that
last time I showed this to someone who does this sort of rework
periodically, the first reaction was a sharp intake of breath!

-- 
Pete						Peter Turnbull
						Network Manager
						University of York