Re: Masking on VIAS ?
Hi,
Solder masking the pcb is to avoid the shorts and oxidation. shorts are possible while its goin for reflow assembly after fabrication,it is must for production boards.
whereas in the prototype it is not required to mask the boards since lots of testing will be going on till its ready for mass production hence they choose via filler.
Solder masking is just the thin layer over the finished board,while via filler is used to fill in the via holes for protect from the shorts caused during assembly.
They test the board after solder masking with flying probes,other alternative for solder mask is Via Filler as i told u earlier.
Some fabricators use both the methods for better protection for eg,assume u have a bga and vias underneath,best way is to fill the via with filler and then soldermask
the board by this it is more protected from short.
you can have this document from the Pcb Fabricator,they may help you on this regard.
Thanks & Regards
Ramesh