JF,

If you make the solder mask 1:1 scale of the hole the fab shop will swell it
per their manufacturing tolerance. 

Solder mask is used to protect traces, vias and copper exposure so if you
swell the solder mask on your pads, use the same value for your non-plated
holes. 

i.e.: if you don't swell any solder mask pads in your PCB library parts,
don't swell the non-plated mounting either. You are basically allowing the
fabrication shop to auto-swell the solder mask globally using their CAM
software. 

Tom

Tom Hausherr
President 
13730 Sorbonne Court
San Diego, CA 92128
858.592.4826 Office
858.859.5371 Cell
[log in to unmask]  


-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of JF
Sent: Monday, February 25, 2013 11:38 AM
To: [log in to unmask]
Subject: [DC] Solder Mask requirements for unplated holes

Hi All,

This should be basic, yet I can't remember the requirement nor where to find
the info (which spec).

We have a board with some unplated holes and a copper plane on both the top
and the bottom. Of course, the copper planes are recessed from the hole but
I can't remember if the Solder Mask should be flush to the holes (some are
mounting holes), or just covering the planes + a certain distance.

Thanks in advance!

JF

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

----------------------------------------------------------------------------
-----
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
16.0.
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL) For additional information, or contact Keach
Sasamori at [log in to unmask] or 847-615-7100 ext.2815
----------------------------------------------------------------------------
-----



______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0.
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------