Hi, Steve,
We ran into the same problem (more or less) - thermal management
requirements and solutions conflicted with the VME spec (which spec did you
go with, by the way?).
One solution we considered, but didn't implement owing to expense, is to
"step" the PCB so that it's the right thickness at the card guide edges and
at the P1/P2 connector areas. Is that possible with Stablcor? - I don't
know. Makes routing traces to the connectors a bit circuitous too (pun
intended). The board thickness outwith these areas is not important, as
long as it, plus the component height, doesn't exceed the envelope max.
You'll need some pretty light-weight copper and very thin separation layers
to fit 16 layers into the spec'd thickness. Good luck!
Peter
Stephen
Gregory To: [log in to unmask]
<SteveZeva@AO cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST
L.COM> Aero/ST Group)
Sent by: Subject: [TN] VME stuff again...
TechNet
<[log in to unmask]
ORG>
01/23/02
10:41 AM
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respond to
SteveZeva
Hey all ya'll!
VME stuff again. Pretty strict standard. Gotta new technology out there
called Stablcor from Thermalworks, problem that we're seeing is that board
thickness is going to increase, which violates the VME spec's. Not just
from
the card-guide aspects, but will change the dimension where the P1 and P2
connectors interface with the backplane on a standard VME card cage.
Just wondering if anybody has anything out there (connectors, etc.), that
will allow you to "shoe-horn" ten-pounds, inna 1-pound bag, that will
comply
with VME spec's.
This board is 16-layers, within .063" without Stablecor, if we use 2-layers
Stablcor, it will increase .020-.025", with 3-layers Stablcor (the best, as
far as thermal dissapation and CTE solutions), it will increase .030-.035".
This Stablcor material sounds like a really good solution for thermal and
CTE
solutions, but has a hard time staying within the dimensional spec's that
are
called out in the VME spec's...trying to change these spec's I know is an
act
of God...it's there, and it's done.
Just wondering if anybody else has explored this material, and have come to
a
dead-end like I have....because of the reasons like I have.
-Steve Gregory-
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