Read the specification carefully Chet 1.4.2 Contact Surfaces 'The use of imm. Silver...is not currently recommended for...Class 3'. I found nowhere else in the document that mentions this finish as being unsuitable for Class 3 application. Table 3-1 of the same (IPC-4553) gives acceptability criteria for all three classes... Sounds like this surface finish is only 'not recommended' for Class 3 applications with contact surfaces... Hope this helps Cheers -- Ian -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Harner, Chester Sent: Wednesday, September 30, 2009 11:03 AM To: [log in to unmask] Subject: [TN] Immersion Silver for Class 3 Boards The revised Immersion Silver IPC spec (4553A) indicates that Immersion Silver is not recommended for Class 3 boards. There is no stated reason. I have been looking into Immersion Silver for all the same reasons as everyone else, to replace HASL for flatness etc. It looked very good until the Class 3 problem. Does anyone know why IAg would not be recommended for Class 3 boards? Chet Harner Sr. Engineer Crane Hydro-AirePO Box 7722 Burbank Ca - 91510 818-526-2600 x3557 ------------------------------------------------------------------------ -------- We value your opinion! How may we serve you better? Please click the survey link to tell us how we are doing: http://www.craneae.com/ContactUs/VoiceofCustomer.aspx Your feedback is of the utmost importance to us. Thank you for your time. ------------------------------------------------------------------------ -------- Crane Aerospace & Electronics Confidentiality Statement: The information contained in this email message may be privileged and is confidential information intended only for the use of the recipient, or any employee or agent responsible to deliver it to the intended recipient. Any unauthorized use, distribution or copying of this information is strictly prohibited and may be unlawful. If you have received this communication in error, please notify the sender immediately and destroy the original message and all attachments from your electronic files. ------------------------------------------------------------------------ -------- --------------------------------------------------- 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 -----------------------------------------------------