Ingemar, Our board vendors know not to send us IAg boards if there are "exposed copper pads" (i.e., features not plated). If they happen to miss them in their inspection (accidentially or not)our operators at stencil printing reject boards that have exposed copper pads. We don't use lots of ENIG boards so we have little experience with ENIG solderability. I think it is safe to say that if a copper pad changes color when ENIG plated the copper pad should be solderable. However, once plated with ENIG you can no longer solder to the copper, you must solder to the nickel. Our limited experience indicates that nickel easily passivates and if it does it solderability degrades. One experiment we did was to Temperature/Humidity condition ENIG and IAg boards and then do double sided surface mount solder assembly. The ENIG boards had solder defects and the IAg didn't. The 4 microinches of IAg will not stop diffusion of the underlying material any more than 5 microinches of IAu on ENIG boards. However, the under lying material on IAg boards is copper but for ENIG boards it is nickel. The flux we typically use were designed to work with copper oxide but they don't touch nickel oxide. Regards, George George M. Wenger DMTS Bell Laboratories Princeton, Supply Network Solutions Engineering Research Center FMA / AQA / RCA Lab (609) 639-2769 (Office); 3210 (Lab); 2343 (Fax) [log in to unmask] -----Original Message----- From: Ingemar Hernefjord (EMW) [mailto:[log in to unmask]] Sent: Friday, January 26, 2001 4:22 AM To: [log in to unmask] Subject: Re: [TN] Silver vs OSP surface finish Interesting George, is that a std among board makers or do you have to imply that method in your own Incoming Inspection? In the later example it's too late, the boards are already delivered, so I assume it's something one has to perform immediately before final plating. My question: is there a corresponding inspection method for judging nickel solderability before gold immersion is put on? I talk for ENIG of course. There are many soaps that react with nickel but using a std method would be best. Wetting balance on test coupons will probably not tell the whole truth. Ingemar Hernefjord Ericsson Microwave System The primary advantage of IAg is that it changes the color of the copper pad. OSP doesn't change the color of the copper pad. We use IAg not as a solderable surface finish; we use IAg as a visual inspection aid to know that the underlying copper is solderable (i.e., if the copper changes color because the silver plated on it we know that the board fabrication process didn't leave any residue such as solder mask or incomplete tin strip on the pad that won't show up until you commit expensive components at assembly. Regards, George George M. Wenger, DMTS Bell Laboratories Princeton Supply Network Solutions PO Box 900, Princeton NJ 08542-0900 Route 569 Carter Rd., Hopewell, NJ 08525 (609)-639-2769 (Office), 3210 (Lab), 2343 (Fax) [log in to unmask] -----Original Message----- From: Michael Forrester [mailto:[log in to unmask]] Sent: Wednesday, January 24, 2001 10:51 AM To: [log in to unmask] Subject: [TN] Silver vs OSP surface finish What are the advantages of using Silver (Alpha level) Vs OSP (Entek) as a surface finish? Since Alpha level has an OSP over the silver why bother with the silver? Wouldn't less interfaces between the component and trace be better? Thank you. Best Regards, Michael Forrester LeCroy Corp. ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------