Here are a couple real life reasons I have run into:

Tenting of larger via holes without worry about unpolymerized LPI in the
via, and the associated defect known as "anthills".

The cost of changing the drawing to allow LPI, when Dry film was called
out.

The improper, yet still done, practice of using the soldermask as an
insulation layer between a metal grounded component body and active traces
running underneath.

It worked last time, don't want to change any thing.

The buyer who is placing the order has no authority to push back for design
changes, or the design is so old, there is no one responsible for the
design anymore.  No way are you going to get the buyer to take
responsibility for a product design change.




George Franck
Quality Assurance
703 295 2635



                      Steve Gregory
                      <[log in to unmask]         To:      [log in to unmask]
                      OM>                      cc:
                      Sent by: TechNet         Subject: [TN] Why Dry film Solder Masks?
                      <[log in to unmask]
                      >


                      01/21/2004 08:17
                      PM
                      Please respond
                      to "TechNet
                      E-Mail Forum.";
                      Please respond
                      to SteveZeva





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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