Some LPI inks don't work well plugging holes, they tend blow out of the
holes during leveling.  It's also difficult to plug with LPI and not gob too
much ink into the component holes.  We used to selectively plug vias with
SR1000 using a drilled aluminum foil with the seleced vias holes in it and
screen the ink into the hole before LPI.  Don't worry about getting ink on
the surface of the via, since it's covered by LPI later.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Mark Hargreaves
Sent: Thursday, September 28, 2000 11:57
To: [log in to unmask]
Subject: [TN] plugging vias w soldermask


Hi All,
     Here's the scenario: We're making a small board with a 133 pin PGA.
Many vias between pads (Vias are 12 mil hole/ 25 mil pad). Customer wants to
avoid shorts under the PGA during assembly and is requesting that we plug
via holes and cover the vias on the part side.  What's the best way to do
this.  (We've got LPI and SR1000 to work with).


Thanks,
Mark Hargreaves
EMDS

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