In a message dated 12/20/00 12:49:12 AM Eastern Standard Time,
[log in to unmask] writes:

<< Hi all,
 This is great idea to get vias plugged from both sides.
 What are the working techniques for this?I presume all of us know how to do
 it from one side,but from both sides?
 Any practical ideas?? >>

I originally didn't suggest plugging from both sides as [1] the resulting
"drum"-effect can result in ruptures in subsequent thermal excursions (the
trapped air within the via expands) and [2] the relative thick deposits of
mask in the holes oftentimes do not fully cure and [3] double-sided via
plugging is a cost driver by most PCB fabricators.

That-said:

The favorite method for double-sided via plugging is using double-sided
screen printing and an epoxy-based solder mask, although incorporating screen
plugging in the silk screen(s) can be a cost & time saver (if you don't mind
white or yellow plugged vias). Also, make the vias as small as practical for
your manufacturing processes.

Cheers!

Bob Lazzara
Circuit Connect, Inc. - Atlanta
TEL:    +1 706.245.4232
FAX:    +1 706.245.4299

www.CircuitConnectInc.com

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