David:

For standard technology and screened soldermask we prefer a soldermask
clearance of .008mls
For higher technology pcb's and liquid photoimageable mask we prefer a mask
clearance of .004mls although tighter clearances are achieved..
A 1:1 will bleed mask on pads and or in the holes.
These are general guidelines. Our CAM dept. generally check the design out
for soldemask clearances making sure no adjacent traces/pads are exposed
depending upon the thickness of the pcb and  soldermask.

Sona Sitapara
Fineline Circuits Inc.



> David Hoover wrote:
> > I am in the middle of a discussion/debate with assemblers on one side
and
> > designers on the other.
> >
> > The question is:
> > What would your shop prefer to receive from the designer for soldermask
> > features?
> >
> > either
> > A) 1:1?  (Soldermask clearance same as the holesize, padsize,
> > surfacemount, or
> >               clearanced feature size)
> > or
> > B) Soldermask Clearance set at some value over the pad/feature/SMT size?
> >     (Like 3 mils per side)
> >
> > Thanks for any and all responses,
> >
> > David Hoover
> > ---------------------------------------------------
> > Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
> > To unsubscribe, send a message to [log in to unmask] with following text
> > in the BODY (NOT the subject field): SIGNOFF Technet
> > To temporarily halt or (re-start) delivery of Technet send e-mail to
> > [log in to unmask]: SET Technet NOMAIL or (MAIL)
> > To receive ONE mailing per day of all the posts: send e-mail to
> > [log in to unmask]: SET Technet Digest
> > Search the archives of previous posts at:
http://listserv.ipc.org/archives
> > Please visit IPC web site
> > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
> > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
> > ext.5315
> > -----------------------------------------------------
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
> -----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------