Ron,

I've seen this done a couple of ways, both with LPI soldermask:

1) Give top/bottom soldermask film with the vias covered; on fab drawing
say, use LPI soldermask, apply per IPC-SM-840, Class "X"

2) Give top/bottom soldermask film with the vias covered; on fab drawing
say, use LPI soldermask, apply per IPC-SM-840, Class "X". And supply
film layers depicting "button plugs". The fab house will apply a "button
plug" over the vias prior to soldermasking.

Both applications work, but you will first need to determine with your
manufacturing department which is more practical and reliable. Make
sure you get your fab house(s) involved in this discussion. This is
becoming a common practice in manufacturing, but the wrong application
can spell disaster!

Good luck,


Mitch Morey
# Sr PCB Designer #
ComStream Corp
San Diego, CA 92121
Phone: (619)657-5338
Fax    : (619)657-5408
EMAIL: [log in to unmask]

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 PCB layout is like fine art. You have to DIE to be famous!
_____________________________________________
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>>> Ron Payne <[log in to unmask]> 03/18/98 07:58am
>>>
We have 0.016 vias and are considering tenting vias both sides with
soldermask. What is the recommended method for doing this and getting
complete tenting without breaks or bulging out?

We do not want dry film on the entire board.

Thanks......Ron

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