I dissagree with your last statement.  The reason I cover my vias
is to remove them from the solderability inspection.  My
inspection says that I have to inspect every solder joint that gets
filled with solder for wetting, etc...  If my via is uncovered it gets
filled with solder when passed over the wave and it becomes an
inspectible item.  Granted, if I'm using a solder paste the vias
don't get the extra solder on the pads.  This also means that if
the via is uncovered, I can't have it under a component where it
can't be inspected.  That wasn't too much a problem with
thru-hole, but surface mount, forget it.  I'd lose 90% of my via
placements.  Just an opinion from the other side of the fence.


>>> <[log in to unmask]> 11/11/97 07:14pm >>>
Dry film solder mask is now about dead.  At least that is what
I see.  LPI is being spec'd out in 90% of the $250M worth of
boards my company does.  Dry film is very easy to use for
tenting purposes while LPI is not that easy and requires more
than one process.  However, the benefits of LPI is worth the
xtra problem.  Most of the people I deal with require 'plugging"
with LPI on the circuit side only.  They also prepare a special
artwork to show which holes get plugged.  Some people use'
epoxy screening ink to plug, some plug from both sides with
more LPI, some use other screening techniques.
The winner I think is plug from circuit side only (this prevents
entraped gases and use an epoxy ink as the plugging agent.
There will be a lot of no's and yes's, and they may be right,
but I am speaking from personal experience both as a user
 a producer and a seller.
I don't want to knock dry film mask on the air, and if you want
my views on this, email me direct.
On another note, you realy do not need to fill unused holes
unless
you are worried about whistling testers.......

##############################################################
TechNet Mail List provided as a free service by IPC using
LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to
[log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional information.
For the technical support contact Dmitriy Sklyar at
[log in to unmask] or 847-509-9700 ext.311
##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################