It's a very poor Cu alloy with a thermal conductivity that low, you're
talking BeCu at that level. 395 is about right for high purity material
Ian Fox
TRW AS
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: 29 April 2002 06:40
To: [log in to unmask]
Subject: Re: [TN] Via Plug
Michael,
My thermal engineer assures me that the K value for copper is between 150
and 200 W/mK, but even so, your point about replacing CB100 (now CB101, by
the way) with additional copper plating is a valid one, and offers much
simpler, quicker and less costly PCB fabrication.
The only caveat I would add is, make sure the ductility for your additional
copper plating thickness is enough to avoid cracking the barrels under
temperature cycling, especially if using FR4.
Peter
"Mcmaster, Michael" <[log in to unmask]> 26/04/2002 11:58 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to "Mcmaster,
Michael"
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] Via Plug
John
The DuPont CB-100 will increase the amount of heat that can be conducted
through the barrel. My experience with it that most people overestimate
what it can do. I've done calculations that show for a 0.020" drilled hole
with 0.001" copper barrel, adding CB-100 only increases the amount of heat
by less than 5%. The reason is the CB-100 has a thermal conductivity of
5.23
W/mK vs 395 W/mK for copper. Even though CB-100 makes up the majority of
the cross sectional area, it only adds a little to the "thermal" cross
section.
I always recommend that potential users of this technology run the numbers
themselves and balance the potential cost increase with the improved
performance.
> ----------
> From: John Foster[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;John Foster
> Sent: Tuesday, April 23, 2002 12:06 PM
> To: [log in to unmask]
> Subject: [TN] Via Plug
>
> Hello, I am new to this listserver. I must say that it is very
> informative. I wish I had known of it long ago.
>
> I have a question about via plugging. Right now
> our board vendor is doing our via plugs with
> I guess with a standard epoxy. We are trying
> to find a solution that would give us a much
> better thermal performance.
>
> We are looking at silver epoxy and this
> material from Dupont. Does anyone know of
> some material that would give us a really good
> thermal performance. We are in a commercial
> environment. So the material does not have to
> meet industrial specs.
>
> Any input on this matter would be greatly '
> appreciated.
>
> Thank You
>
> John Foster
>
>
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