As Joyce pointed out, Arsenic may be present in very low levels as a grain refiner in Au. Electroless Ni can be plated with a boron reducing agent resulting in some boron in the Ni, but this would be unusual for a PCB pad finish. Best regards, Leo Leo M. Higgins III, Ph.D. Vice President, Technical Operations ASAT, Inc. 3755 Capital of Texas Highway, Suite 100 Austin, Texas 78704 office phone 512-383-4593 mobile 512-423-2002 [log in to unmask] www.asat.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Richard Kraszewski Sent: Monday, June 26, 2006 9:20 AM To: [log in to unmask] Subject: [TN] Boron & Arsenic Can anyone suggest where in an assembly process I am likely to find Boron and Arsenic? I've been presented with an assembly that has some "black crud" on and around some reflowed SM solder joints. Analysis came back with not only the "usual suspects" but also these 2 elements. While I am not eliminating it, for various other reasons I am discounting the likelihood of the solder paste being the source. Thanks in advance for your thoughts. Rich K --------------------------------------------------- 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 -----------------------------------------------------