I just did a calculation for some of our boards that use this via plug
material for enhancing thermal transfer between chips and thermal planes.
The calculation was to see by how much I would have to increase hole
plating thickness by in order to completely replace the epoxy in terms of
thermal conductivity.

I'm talking about a 24 mils diameter hole, plated initially to 1/2 oz
copper minimum and filled with epoxy. The board is 63 mils thick. Can you
guess what the increase is? ..... It's actually only 0.2 oz or 0.28 mils,
according to our thermal engineer. So why go to all the trouble and expense
of filling holes if the only purpose is thermal - a fairly small increase
in plating thickness is all that's needed.

Peter



Earl Moon <[log in to unmask]> 30/04/2002 05:49 AM
Sent by: TechNet <[log in to unmask]>

Please respond to "TechNet E-Mail Forum."; Please respond to Earl Moon

             To: [log in to unmask]
             cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
             Subject: Re: [TN] Via Plug








Don't mean to but in, but what the hell. Just think how much surface copper
would be plated and how much resist would have to be applied and how much
plating overhang would be involved even with several resist layers applied,
etc..

MoonMan

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