I echo your comment about this not being an immersion sil Denny, I echo your comment about this not being an immersion silver problem. We've seen these types of defects, fortunately very infrequently, and they are usually associated with imaging issues. If there is an appropriate amount of copper in the PTH's the amount of copper consumed during a replacement reaction that deposits only a few microinches of silver should not etch enough copper to cause the ring voids. Regards, George George M. Wenger Andrew Corporation Wireless Network Solutions Senior Principal FMA / Reliability Engineer 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [Office] (732) 309-8964 [Cell] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz Sent: Friday, December 15, 2006 3:38 PM To: [log in to unmask] Subject: Re: [TN] How does this happen? In a message dated 12/15/2006 8:59:36 A.M. Eastern Standard Time, [log in to unmask] writes: Another possibility is that the single panel was reworked through immersion silver. Immersion silver is notorious for etching copper as it plates. I've seen it lift narrow traces right off the substrate. The voids probably just correspond to naturally low areas of copper plating, whether from PTH or electrolytic copper. ************************** I still vote for an imaging problem and rework (maybe more than once) at that step. There is nearly breakout of the surface pad at the 2:00 position of the holes. I am 99.9% sure this is NOT an immersion silver problem - first, the fine trace is OK, and second, the small hole appears fine. Any silver attack problem is usually associated with an electrochemical cell set up between large copper and small copper areas (fine traces). These sort of "electrochemical cells" have been shown for years - such as where 0.5 ounce inner layers in holes are recessively etched, compared to adjacent 2 ounce inner layers in MLB holes. Denny Fritz MacDermid, Inc. --------------------------------------------------- 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 ----------------------------------------------------- ------------------------------------------------------------------------------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any unauthorized use of this email is prohibited. ------------------------------------------------------------------------------------------------ [mf2] --------------------------------------------------- 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 -----------------------------------------------------