You are 95% correct. The silver saver paper is simply a sulpher-free paper. Oxygen can and will tarnish the immersion silver finish on PWBs, but much more tarnishing will take place if a sulpher-laden paper is used (nearly all paper is made with sulpher). To really keep the boards from tarnishing, use the silver saver paper liners and hermetically wrap the brick of boards with a vacuum-seal low-outgassing wrap. But Mr. Bogert's problem has nothing to do with immersion silver finishes on the pwb. In his particular case, the black oxides showing up on the silvercoated wires are not from the silver finish on the wire strands, but from the PREVIOUS flux residue used to tin the wires at the OEM. The note from Mr. Bogert references the tinning process using 63/37 solder done by the OEM. When you leach some of that flux back out from under the insulation, add some different flux to it from the WRMAP 10 wire solder, and try to solder silver-finished wires to a gold ring that has 50 uinches of gold on it, you can bet your supper it will have poor wetting and black crud. The poor wetting is from too much gold. The black crud is from a reaction between the WRMAP flux and the ORH1 or ORH0 flux the OEM probably used. One should never tin wires with any flux other than a no-clean or RMA flux, and never mix flux chemistries when soldering. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Thursday, March 02, 2006 11:38 AM To: [log in to unmask] Subject: Re: [TN] Black "crud" on connector solder connections causing electrical short-circuit - Need Help Please Hi Ramon - I have several references show that silver oxide is transparent, silver chloride is yellow/brown , and silver sulfide as black. The reference you cited (where did that information come from?) shows that the oxidation reaction is associated with a color change which I don't believe is correct. Also, when "silver saver" paper is used, silver finishes do not tarnish and I know that the "silver saver" paper does not prevent oxygen from the surface of the silver plating. Ok TechNetees (George W., Rudy, George M, Gerard O., John B.etc.) what do your references information say? Dave "Dehoyos, Ramon" <ramon.dehoyos@ng c.com> To "TechNet E-Mail Forum" 03/02/2006 09:37 <[log in to unmask]>, AM <[log in to unmask]> cc Subject RE: [TN] Black "crud" on connector solder connections causing electrical short-circuit - Need Help Please Read below: Silver metal will oxidize spontaneously upon exposure to free oxygen. This process is commonly referred to as "tarnishing". The chemical reaction describing this proces is shown below. 4 Ag (s) + O2 (g) (r) 2 Ag2O (s) Silver metal is a grayish white color, silver oxide is a black color. This contrast in colors makes tarnished silver appear much different in appearence than untarnished silver. This explains why so much physical and chemical effort is spent in removing the tarnish from silver objects. Thermodynamic Constants of Compounds of Interest [1] Compound DHof (kJ/mol) DGof (kJ/mol) So (J/mol.K) Ag (s) 0 0 42.6 O2 (g) 0 0 205.2 Ag2O (s) -31.1 -11.2 121.3 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Thursday, March 02, 2006 10:29 AM To: [log in to unmask] Subject: Re: [TN] Black "crud" on connector solder connections causing electrical short-circuit - Need Help Please Hi Leo! I might be mistaken but I thought that silver oxide (Ag2O) was transparent (e.g clear). The other species you mentioned my references show as black or other various colors. Dave Hillman Rockwell Collins [log in to unmask] Leo Higgins <Leo_Higgins@ASAT .COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 03/01/2006 10:37 Re: [TN] Black "crud" on connector PM solder connections causing electrical short-circuit - Need Help Please Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to Leo Higgins <Leo_Higgins@ASAT .COM> Might be a coincidence that the 'crud'in the referenced, but not seen, photos is black, but Ag2O, Ag2CO3, Ag2S, AgCl, and AgNO3 are all black. Best regards, Leo Leo M. Higgins III, Ph.D. Vice President, Technical Support Operations ASAT, Inc. 3755 Capital of Texas Highway, Suite 100 Austin, Texas 78704 office phone 512-383-4593 mobile 512-423-2002 [log in to unmask] www.asat.com The information contained in this electronic message is CUSTOMER/SUPPLIER PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution and copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by electronic mail. Thank you. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Richard Kraszewski Sent: Wednesday, March 01, 2006 8:01 PM To: [log in to unmask] Subject: Re: [TN] Black "crud" on connector solder connections causing electrical short-circuit - Need Help Please I don't see any photos. Rich K / KEDS 260.925.8719 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of - Bogert Sent: Wednesday, March 01, 2006 6:51 PM To: [log in to unmask] Subject: [TN] Black "crud" on connector solder connections causing electrical short-circuit - Need Help Please March 1, 2006 Folks, the three attached photographs show some problems an OEM of ours is having. Specifically, he hand solders two MIL-W-16878 silver coated stranded wires to a MIL SPEC connector that has solder eyelets plated with 50 microinch of gold. Sn10 WRMAP flux cored solder is used with no additional flux added. The OEM has had recent rash of failures in fielded equipment. We do not know the cause yet. We are having the black residue shown sent out for analysis but no results yet. The solder joints do not appear to be acceptable to me. One can see exposed gold on the gold-plated connector contact eyelets. Appears to be non-wetting??? Also, appears to be excess solder since strands are not always visible in the joint. The OEM tins the stranded wire with Sn63 prior to soldering. Do you folks have any ideas on what the problem could be? There is detailed info on the photographs on the application of the product. The connector provides power to a solenoid that actuates a valve. The application is hermetic sealed by welding the connector to a metal housing that contains the solenoid winding. The wires connecting to the connector are the MIL-W-16878 silver coated stranded lead wires that connect from the gold plated connector pins on one end to the MIL SPEC magnet wires on the solenoid on the other end. The solenoid is varnished (DIP process, no vacuum). I am aware that silver plated wire in an SO2 environment can cause corrosion, but we use a lot of silver coated wire in other product with no known corrosion problems. The connector housing has a small vent port into which air is applied to do a pressure seal test. After the pressure test is completed, the vent hole plug is welded closed. We are checking to see if the air could have had moisture in it. Dielectric strength, insulation resistance and functional testing is done on the solenoid after assembly is completed and all tests passed. However, failures occur in the field. Since the flux used in the SN10 flux-cored solder is RMA, one would normally not expect the black residue to be due to RMA flux but I am not sure. We will probably know for certain after we get the test results on the black crud. Any insight you may have into into this problem would be appreciated. Please e-mail your response to following e-mail address: [log in to unmask]<mailto:[log in to unmask]> --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 1.8e 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 1.8e 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 1.8e 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 1.8e 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 1.8e 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 -----------------------------------------------------