Marcelo

We have used a two step soldermask process to tent vias. First we put a layer of dryfilm down and print it
with via image. Then coat the board with liquid soldermask. Then print that image. This produces a part
with tinted via's and liquid photoimageable to ensure that there is no entrapment in the via holes. If you
have any questions contact me off line.
Regards,
Tim Snodgrass
Young Electronics
818 407-4024

Chan, Marcelo wrote:

> We have tried different approaches to tenting/plugging vias for BGA and some
> backplane applications using LPI and screened SM with limited success...PWB
> vendors claim they could do it, but we are still looking for some one who could
> do this on 100% of the vias with no pin holes and it has to be done on both
> sides to prevent entrapment of cleaning solutions...the via sizes that we have
> in mind can have a finished hole diameter as large as 22 and as small as 13
> mils...Can someone share their 'hands-on' experiences on this issue with me
> through Technet or even off-line?
> Thanks
>
> Marcelo Chan
> Lead Engineer - Advanced Manufacturing Technology
> Electronics Systems Sector, Harris Corp., FL
>
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