[PCB_FORUM] Re: Anti Soldermask

 Robert,

It is infinitely more dangerous to tent only one side of a via. During
assembly contaminates can stay inside this "cup" you have provided.

Tenting both sides with dry film soldermask is one option. For dry film
the recommend
maximum size to tent is .025" finished. Another is plugging the vias
with non-conductive
via fill material and then using LPI to cover. Conductive via fill is
also available if needed for
thermal issues.

As far as getting the job done I recommend using different padstacks for
your vias.
You are going to be selecting them anyway. Why not do it right?


Jerry


-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Robert
Szumowicz
Sent: Thursday, April 05, 2007 10:25 AM
To: PCB forum
Subject: [PCB_FORUM] Anti Soldermask

Hi All,

is there a way in Allegro to cover some vias by a soldermask but not by 
replacing the definition of via. The simplest would be to draw a shape 
which would work as anti-soldermask, i.e. it would clear all existing 
soldermask openings over the shape area. I would like to quickly cover 
vias under some components leaving second side of vias not covered by a 
solder mask. The board uses several via sizes and changing manually vias

to: covered on top / covered on bottom / covered on both sides is a lot 
of work. One possibility would be to modify an art output, but the 
preferred method is to have it done in the design. If I could embed such

feature into footprints would be even better.

One more question: I've read recently that tenting vias (covering by 
soldermask on both sides of the board) is not recommended. Is that a
true?

thank you for suggestions,
Robert

-----------------------------------------------------------
To subscribe/unsubscribe: 
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe

To view the archives of this list go to
http://www.freelists.org/archives/icu-pcb-forum/

Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------
-----------------------------------------------------------
To subscribe/unsubscribe: 
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe

To view the archives of this list go to 
http://www.freelists.org/archives/icu-pcb-forum/

Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------

Other related posts: