Hello, all:

I am wondering what to do about vias.  I have a design for an 8-layer 0.090
in. PCB with about 700-800 vias 32mil pad, 18mil hole (no BGAs).  Since the
vias can be very close (6 mil) to other vias and pads, I want to cover the
vias with either soldermask or tent them.  What is the difference between
just covering them with soldermask, or tenting?  I guess tenting is where
the via holes are filled with an inert material to plug them, right?

I have read in trade journals (such as PCB Design) that trapping residual
PCB etching chemicals inside vias can "eat them out" over time and result in
boards going bad after X years of service.  If this is so, wouldn't
soldermask AND tenting both trap these chemicals inside the via holes?

Best regards,
Ivan Baggett
Bagotronix Inc.
website:  www.bagotronix.com



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