Using CIC as a constraining core is primarily associated with using LCCC's
(TCE matching), not QFP's though this option is possible. Polyimide is the
material of choice for flight applications (thermal management) when
properly cured. Most manufacturers reside on the West and East coasts with a
few in the country's middle. Several still practice this type processing.

I would also note using CIC as a tailoring core material instead of one to
constrain. The results are much the same for thermal management and those
for TCE but save considerable weight and cost as well as reducing process
difficulties in the board shop.

For thermal condution, building in heat pipes from either core types is
widely used. When using cold wall designs, typical in flight hardware, the
mounting "rails" do the job to atmosphere.

Earl Moon
----- Original Message -----
From: Phil Dutton <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 16, 1999 12:54 AM
Subject: [TN] Conduction Cooled PWBs


> Hello,
>
> I'm wondering if anyone can give me any information on the design of
> conduction cooled boards for use in an airborne military environment?
> I'm intending to use VME size boards with a copper-invar-copper
constraining
> core, and an aluminum stiffening frame with wedge-locks.
> Is there any problem with using FR4 or FR5 material, or should I be
looking at
> something like Polyimide or BT/Epoxy?
> Is it commonplace to use SMT devices (QFP)?
> Also, there are few manufacturers here with any experience producing such
> boards, so any pointers to possible manufacturers would also be
appreciated.
>
> thanks,
> Phil.
>
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