Yes, freezing would extent the time some length but I don't know specifically how long without running the numbers thru the diffusion equation. Dave "John Burke" <[log in to unmask]> 12/08/2009 04:55 PM To <[log in to unmask]> cc "'TechNet E-Mail Forum'" <[log in to unmask]> Subject RE: [TN] Storing of Copper Sheets But will push the time frame out right? John Burke (408) 515 4992 From: [log in to unmask] [mailto:[log in to unmask]] Sent: Tuesday, December 08, 2009 2:51 PM To: John Burke Cc: 'TechNet E-Mail Forum' Subject: RE: [TN] Storing of Copper Sheets Hi John - yes, if that deep freeze is in liquid nitrogen - otherwise diffusion is still going to progress on its merry way to the same end result. Standard freezing temperatures will not slow down the diffusion process enough to prevent degradation. Dave "John Burke" <[log in to unmask]> 12/08/2009 04:48 PM To "'TechNet E-Mail Forum'" <[log in to unmask]>, <[log in to unmask]> cc Subject RE: [TN] Storing of Copper Sheets Unless of course he stores them in the deep freeze........ John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Tuesday, December 08, 2009 2:40 PM To: [log in to unmask] Subject: Re: [TN] Storing of Copper Sheets Hi Bob - unfortunately you are going to lose the solderability of those sheets somewhere in the 6-12 month time frame depending on which immersion tin formulation you are using and due to diffusion issues will lose the solderability of the sheets on a permanent basis somewhere in the 12-24 month time frame depending on the thickness of the immersion tin plating. You may be able to "reactive" the surface for some other operation but you will need to somehow make sure the surfaces to not passivate (aka oxidize) preventing the next process operation. My recommendation is talk to your favorite plating supplier. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] bob wettermann <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 12/08/2009 11:11 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to bob wettermann <[log in to unmask]> To [log in to unmask] cc Subject [TN] Storing of Copper Sheets Dear Technetters: If you planned on storing 10z copper sheets with a bright immersion tin coating for several years in 24 x 24" sheets-how would you do it? We have several internal opinions from interleaving of saver paper to moisture barrier bags to other types of bags. Thanks! Bob Wettermann PH 847-767-5745 --------------------------------------------------- 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 -----------------------------------------------------