Werner, I had a case a while ago with a component plated with 4-5 micron of Ag. It was so thick that it hadn't even been completely dissolved during re-flow. Even so, no issues with the solder joints, even though, the component had been under almost permanent load. I'm not sure whether those joints could have more Ag than they had. :-) Vladimir SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Werner Engelmaier /* <[log in to unmask]> Date: Wed, 15 Apr 2009 16:13:36 To: <[log in to unmask]> Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Hi Vladimir, As Dave points out, if specs are followed, there should be no issues with either 'Ag-embrittlement'; or 'Au-embrittlement.' Of course, the issue was never immersion-anything, but electroplating either Au or Ag. Werner -----Original Message----- From: David D. Hillman <[log in to unmask]> To: [log in to unmask] Sent: Wed, 15 Apr 2009 2:49 pm Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Hi Vlad - yes, the reliability investigation report by the IPC 4-14 committee is complete. Go to the IPC website and search for technical paper IPC-TR-586 which contains the investigation information/details. The Reader's Digest version is: as the silver content of a solder joint increases, there is a corresponding decrease in solder joint thermal cycle reliability - BUT - a solder joint can accommodate much more silver in comparison to gold. If the IPC-4553 Immersion Silver pwb finish specification is followed, there should not be an issue with "silver embrittlement". Dave Vladimir Igoshev <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 04/15/2009 12:37 PM Please respond to [log in to unmask] To [log in to unmask] cc Subject Re: [TN] Gold/Tin Intermetallics, why are we afraid? Werner, We've been through it and not just once. I wish I could have those samples to look at, as I've never seen anything like "Ag-embrittlement". Please correct me if I'm wrong but a couple of months ago Dave H. "spelled out" a final verdict of an IPC committee on the issue. Regards, Vladimir SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Werner Engelmaier /* <[log in to unmask]> Date: Wed, 15 Apr 2009 13:19:34 To: <[log in to unmask]> Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Vladimir, Oh yes, there is 'Ag-embrittlement'?it just never reached the same level of notoriety as 'Au-embrittlement.' The whole 5-year effort of the IEEE Compliant Lead Task Force (CLTF) was started by 'Ag-embrittlement' when TI started production in Singapore and their J-leads were Ag-plated. It all hit the fan when the first customer, IBM in Austin, had PLCCs dropping off the PWBs on bed-of-nail testing. Werner -----Original Message----- From: [log in to unmask] To: TechNet E-Mail Forum <[log in to unmask]>; [log in to unmask] Sent: Wed, 15 Apr 2009 12:41 pm Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Werner, I would say that Ag-Sn platelets do the same thing to solder joints as Au-Sn. There is no "Ag embrittlement". :-) Vladimir SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Werner Engelmaier /* <[log in to unmask]> Date: Wed, 15 Apr 2009 11:45:28 To: <[log in to unmask]> Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Vladimir is correct. "Gold-embrittlement" is the weakening of the SJ structure by too many weak interfaces with the crystalline AuSn-IMC platelets and the solder. The more such IMC [AgSn-IMCs do exactly the same] platelets results in higher density of such interfaces and an increased SJ weakness. The dull, grainy, lumpy appearance stems from these IMC-platelets pocking through the SJ surface. Werner0A -----Original Message----- From: Vladimir Igoshev <[log in to unmask]> To: [log in to unmask] Sent: Wed, 15 Apr 2009 11:29 am Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Because you had different materials at the interface. With thick Au your joints had a relatively wide band of "weak connection" at the Au/Sn-Sn interface. Regards, Vladimir SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Guy Ramsey <[log in to unmask]> Date: Wed, 15 Apr 2009 11:19:59 To: <[log in to unmask]> Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? The point is the connections made on thick gold were substantially weaker than those made to nickel though thin gold. I don't know if there was nickel in the weak connections. But, they were dull, grainy, lumpy and weak, compared to the connections made through thin gold. Guy -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev Sent: Wednesday, April 15, 2009 8:45 AM To: [log in to unmask] Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? It just tells you had good solder joints. In many cases laminate (board) breaks when a load is applied to properly formed solder joints. Regards, Vladimir SENTEC 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Guy Ramsey <gramse [log in to unmask]> Date: Wed, 15 Apr 2009 08:37:31 To: <[log in to unmask]> Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? We build a lot of boards with electroplated gold finish, primarily for the semiconductor test sector of our industry. On one occasion we were populating little printed circuit wave guides with SMT SMA shrouds. We noticed very poor solder appearance and very weak solder connections. Some connections broke while attaching the cables. We determined that the gold plate was 3.8 micron. And judged the thickness of the gold to be the cause of poor mechanical performance of the solder connection. We replaced the boards with versions having about 0.3 micron gold plate. The connections were much stronger. We were able to install all the cables, no connection failures. To satisfy my own curiosity, I attempted to break one of the connectors off the board. The solder connection did not fail. The copper peeled off the board. Thoughts? Guy -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar Sent: Wednesday, April 15, 2009 2:42 AM To: [log in to unmask] Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? Thank you, George, sometimes one needs kind of technical pragmatism. Inge -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M. Sent: tisdag 14 april 2009 23:41 To: [log in to unmask] Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? I think both you and Vladimir are20correct. If the bond Ingemar, I think both you and Vladimir are correct. If the bond sits are room temperature without any power cycling or mechanical stress it probably won't degrade. I assume Vladimir has seen the same kinds of failures I've seen and there has always been a thermal and/or mechanical stress associated with the failures. Regards, George George M. Wenger Andrew Wireless Solutions Senior Principal FMA / Reliability Engineer 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [Office] (732) 309-8964 [Cell] [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Tuesday, April 14, 2009 5:15 PM To: [log in to unmask] Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? You mean that such a bond degrades even if just being in constant room temperature and no power switching? Inge ----- Original Message ----- From: <[log in to unmask]> To: "TechNet E-Mail Forum" <[log in to unmask]>; "Inge" <[log in to unmask]> Sent: Tuesday, April 14, 2009 11:07 PM Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid? > Hi Inge, > > Yes, the intermetallics itself is strong, BUT it doesn't count, as all > failures I've seen goes at the tin/intermetallics interface. The larger > were the platelets, the worse it looked. > > Regards, > > Vladimir > ------Original Message------ > From: Inge > Sender: TechNet > To: [log in to unmask] > ReplyTo: TechNet E-Mail Forum > ReplyTo: Inge > Sent: Apr 14, 2009 16:55 > Subject: [TN] Gold/Tin I ntermetallics, why are we afraid? > > These infamous IMCs are like parias or ghosts in most people's mind in our > business. I shocked our production guys recently by giving the advice to > let > the boards go on. Large crystals and bad looking. But I always try to > avoid > exaggerations. If no serious temp changes are predicted, nor any severe > power switching, why rework and risk introducing failures? The actual > components were very hard to rework, the cost had been unacceptable. I can > see many of you get the coffee wrong. I don't mean to spread quality > distractions, I talk about very few boards and a unique situation. My > statement was based on the fact that a gold tin intermetallic bond is > extremly strong and can last long, if not exposed to what I pointed at > earlier. I expect to be hammered down in the shop floor until only the > nose > is visible.... > > Inge > > --------------------------------------------------- > 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/contentpag e.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > > > > SENTEC > 11 Canadian Road, Unit 7. > Scarborough, ON M1R 5G1 > Tel: (416) 899-1882 > Fax: (905) 882-8812 > www.sentec.ca > --------------------------------------------------- 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 ----------------------------------------------------- ---------------------------------------------------------------------------- -------------------- 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 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 B ODY (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) deliver y 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 -----------------------------------------------------