The immersion silver coatings are very thin, especially when compared to siver filled epoxy. I suspect that immersion silver will start to electromigrate if it's applied to thickly. Additionally, the silver coating gets sucked into any solder used in processing the coupons. Karen Tellefsen - Electrical Testing [log in to unmask] 908-791-3069 Dennis Fritz <[log in to unmask]> Sent by: TechNet To <[log in to unmask]> [log in to unmask] cc 07/15/2009 02:47 Subject PM Re: [TN] Silver epoxy Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to [log in to unmask] Seems to me there is a UL regulation on silver and circuit boards.? I know the immersion silver had to satisfy UL of no dendritic growth.? Anyone on TechNet quote fluent UL? Denny Fritz -----Original Message----- From: John Burke <[log in to unmask]> To: [log in to unmask] Sent: Wed, Jul 15, 2009 1:50 pm Subject: Re: [TN] Silver epoxy Exposed PWB John Burke (408) 515 4992 -----Original Message----- From: Steven Creswick [mailto:[log in to unmask]] Sent: Wednesday, July 15, 2009 10:29 AM To: 'TechNet E-Mail Forum'; John Burke Subject: RE: [TN] Silver epoxy John, We did do not experience electro-migration problems in a hybrid or multi-chip module so long as long-term hermeticity was maintained - to keep the moisture out. From my perspective, PEMs - plastic encapsulated modules do not possess long-term hermeticity characteristics [am sure to ignite a firestorm with that], but they certainly do well in the short-term, and under reasonable environmental challenges. They delay the ingress of moisture - do they delay it long enough for your application is the question. Optically clear molding compounds tend to be worse because - 1) there are no expansion modifiers present [dah!, it's clear], 2) they just don't have the ruggedness of the filled versions ... Therefore, whatever you do to delay the ingress will be to your benefit. Paralyene, some of the new hydrophobic plasma coatings, careful selection and processing [storage, handling, molding and post-cure] of the mold compounds, plating on the lead-frame or PWB. Depends on your requirements.... just a matter of time & voltage, it would seem. You did not really say whether your application was over-molded, exposed PWB, etc... Steve -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke Sent: Wednesday, July 15, 2009 1:09 PM To: [log in to unmask] Subject: [TN] Silver epoxy Many years back (too many) I was working on silver epoxy connected hybrids for high reliability applications. I seem to recall that silver migration is a definite issue. Does anyone have any rules for mitigating this risk such as design clearances between pads etc? Best regards, John Burke Director of Operations http://www.optichron.com 4221 Technology Drive Fremont, CA 94538 Cell (408) 515 4992 Desk (510) 249 5233 Main (510) 249 5200 -- ------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 15.0 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 15.0 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 -----------------------------------------------------