At 11:29 AM 4/24/2002 -0700, John Foster wrote:
>Thanks Jim
>
>Did you do this extra plating selectively. Or did you just overplate the
>whole PCB.

We have a lot of applications where we spec thermal vias to be selectively
plated to a minimum of 3 mils annular copper.
The fabricator drills the thermal vias and selectively plates to 2
mils.  Then they drill and (plate the rest of the board to 1 mil (adding to
thermal via copper as well).

It's way more effective at heat transfer than any conductive epoxy we've
tried.   This approach is also very effective at controlling solder wicking
to the bottom of the board -- we'll use it sometimes when we don't have a
thermal problem but just want to control solder flow into unplugged fields
of gnd vias (saves masking backside).

Dwight

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