This is common with ENIG.  The issue is a build up of potential that
displaces the catalyst in the nickel deposition leaving a skip plating
condition.  The issue is found on common nets that are connected to PWR
layers and more prevalent on these nets with longer runs.  We have some
blind/buried via products that simply will not process in ENIG and we
have switched these to silver. 
      
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 21
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Skweres
Sent: Monday, September 18, 2006 5:54 PM
To: [log in to unmask]
Subject: [TN] ENIG

We have, at times, had an outside plating service have difficulties with
plating of ENIG on our bare boards. The interesting anomaly we have
encountered is lack of plating on certain pads. They tell us there is
something on the surface of the pads but when they return the panels to
us we micro etch (copper looks beautiful) and all pads look similar in
appearance. We even took a panel and coated immersion white tin with out
problems. This tells me that there isn't any thing on the surface of the
copper. There is one thing I did leave out. The pads that aren't taking
ENIG all happen to be in the same net. Has anyone encountered this? It's
almost like there is a charge being created in certain nets not allowing
the ion exchange to happen. Could it be entrapped chemistry within vias?
Any help and/or direction would be greatly appreciated.
Thanks,
 
 
Dan Skweres
Engineering Manager
Bartlett Manufacturing
Phone:847-639-2102 Ext.#230
Fax:847-639-8838


---------------------------------------------------
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 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
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 847-615-7100 ext.2815
-----------------------------------------------------