Thanks to Leon and others for the helpful advice.  This forum rules!

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


----- Original Message -----
From: "ICT Mail" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Wednesday, September 12, 2001 9:38 PM
Subject: Re: [PEDA] via tenting question


> Ivan, we have found that the best solution is PARTIAL TENTING.
> ie You need to cover the annular ring with mask but leave the hole free.
> This allows the via to be flushed of any residual etching chemicals and
will
> still fill if wave soldered.
> Depending on your fabricator and process allowance, typically an 18mil
hole
> could use a 22mil soldermask opening (set your mask expansion to -5mil).
We
> have not had any adverse feedback in our experience.
>
> hope this helps
>
> Leon Fonstin C.I.D.
> Integrated CAD Technologies Pty. Ltd.
> http://www.ict.net.au
> IPC Certified PCB Designers
>
>
>
> -----Original Message-----
> From: Bagotronix Tech Support [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, 13 September 2001 8:11 AM
> To: Protel EDA Forum
> Subject: [PEDA] via tenting question
>
>
> 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
>
>
>
>

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Forum Guidelines Rules:
* http://www.techservinc.com/protelusers/forumrules.html
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to