I've recently specified dry film solder mask on a production board.
I normally ask for LPI.
The only reason being that I couldn't rely on LPI to reliably tent every
via.
The badly tented vias could not pick up solder and fill adequately to
comform to the Class 2 requirements, creating reliability concerns.
Ideally, I would like the vias filled and then tented with LPI, but our
fab shops here in Australia don't do the via filling.

regards,

Phil Dutton.

-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]]
Sent: Thursday, 22 January 2004 11:47 AM
To: [log in to unmask]
Subject: [TN] Why Dry film Solder Masks?


Can anybody tell me why dry film solder masks are still specified?

I don't want to hear; "Because they've always worked good..."

But some clear, concise, reasons for specifying them...

Vacuum at ICT is a dead deal, there are ways to deal with open via's
with
LPI's...Solder fill for via's is a dead deal...either you fill them, or
you don't.

So why dry-films?

So many complications come up with dry film solder masks...

Not only for the bare board manufacturer...but also for the assembler.

Just a question...(for the DoD guys, especially)

-Steve Gregory-

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