Yes, by using a Co2 laser at low power settings. Most, if not all maskings
can be removed from pads and traces with a laser. The mask will be ablated
very easily, and will not harm the metal of the circuitry, as long as very
low power / pulses are used. After laser ablation, process your boards
(unpopulated) through a final clean / acid rinse to remove any remaining
debris. Any small soldermask touchups can be re-applied by hand. If the
laser process (Program & parameters) is setup correctly, you may not need
any touchup at all. Major touchup could be reapplied using a new 'Rework'
artwork / screening / LPI process.  Not sure of any chemicals that can be
used.

Dave Simonik
Sanmina-SCI
Owego NY Division


-----Original Message-----
From: - Bogert [mailto:[log in to unmask]]
Sent: Wednesday, September 15, 2004 5:45 AM
To: [log in to unmask]
Subject: LPI Solder Mask on Class 3 Product; Can it be removed?


September 15, 2004

Does anyone know of a method to remove fully cured LPI solder mask
(IPC-SM-840, Class 3 product) from an FR-4 PWB without damaging the PWB or
otherwise creating possible condition for growing dendrites?

If chemicals can be used, are they non-conductive?

If solder mask needs to be touched up because of missing solder mask,
---------------------------------------------------
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
-----------------------------------------------------
how do folks do this?

____________________________________________________________________________
_
Scanned by Sanmina-SCI eShield
____________________________________________________________________________
_

---------------------------------------------------
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
-----------------------------------------------------