Hi, Jon I am not sure of the cause, but I assumed it to be outgassing. I do not think it was caused by the heat alone. I also know that THHN-type wire was most susceptible to the problem. The tin-coated wires such as UL 7004 less so, but it still oxidized to the point where it would not solder easily. As part of my own business, I used to bring in aviation fueling trucks and wire them and install either the tank and pump or the hydrant/pump systems, and then I installed dead-man switches throughout the trucks connected to a PLC controller. In order to start and drive the truck, everything had to be in place, the driver needed to be seated, the brakes off, the hose wound onto the reel, the valves locked, etc. We used DOD-STD THHN automotive wire, and I recall having a spool of this wire come in and it was black under the insulation. There were no outward signs that anything else was wrong with the wire. I later found out that the supplier had a warehouse fire. Later in life, I experienced wire turning black after it had been soldered to circuit boards. It turned out that the CEM used a standard UL 7004 wire and baked the assembly after it was soldered to cure an epoxy that was used to hold down the wires. When we went to rework one, the stranded, tinned UL 7004 hookup wire was black inside of the insulation. The bake temp was only 65 deg. C. for 4 hours. The same lot of wire still on the spool showed no signs of oxidation. Strange things happen. -----Original Message----- From: Roberts, Jon [mailto:[log in to unmask]] Sent: Thursday, January 18, 2007 4:04 PM To: Stadem, Richard D.; TechNet E-Mail Forum Subject: RE: [TN] SHELF LIFE OF STRANDED WIRE Richard, First, I thank you. I am also from the old school (actually was an Navy Civilian Instructor in Indianapolis In working at the Naval Avionics Center in the late 80s and all through 90s until DoD cancelled the Mil Standards for soldering. I am glad you reminded all about OA flux and we do not use that anywhere here. I did not know about heating of wire can induce oxidation so is the insulation out gassing causing the oxidation? Jon -----Original Message----- From: Stadem, Richard D. [mailto:[log in to unmask]] Sent: Thursday, January 18, 2007 3:41 PM To: TechNet E-Mail Forum; Roberts, Jon Subject: RE: [TN] SHELF LIFE OF STRANDED WIRE If the wire is oxidized on the surface to the point where it will not solder, the surface resistance will be higher and there may be some reduction in conductivity when mechanically crimped. If they are oxidized well up under the insulation either they oxidized prior to insulation application or there was a reaction inside the insulation. If a spool of wire is heated up over 90 C I know that it can oxidize under the insulation. A word of caution: Do not attempt to use a highly active OA flux to pre-tin oxidized wire, as the OA flux will seep up inside the insulation and cannot be washed away. Only a no-clean or RMA flux should be used when tinning wires, and the dwell time in the pot should be of such length that full activation of the flux occurs. The procedure I was taught by the old school is to dip the wire in IPA, then dip only the portion to be tinned (or slightly less) in the flux, and then dip in the solder such that it wicks up under the insulation a minimum of the wire thickness. After the wires were tinned they were collectively dipped in alcohol again to remove as much of the flux residue as possible. Automated tinning systems are set up to perform the tinning in much the same manner. That's my 2 peso's on that. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon Sent: Thursday, January 18, 2007 2:02 PM To: [log in to unmask] Subject: Re: [TN] SHELF LIFE OF STRANDED WIRE Thanks for all the inputs. This is a picture of a purchased item containing multiple wires that are formed into a fusion lug at one end. The other ends we strip and some wires are soldered into a connector and others are crimped to pins. The wire when looking very dark (almost black) will not take solder and we use a solder pot. We have cut back up to 12" and still found unsolderable wire. We now have come across wire on spools in house that is very dark in color that was manufactured in 05 and 06 and stored in a controlled environment for temperature and humidity here. Main question I have is can you use wire that does not take solder for crimping operations? Again thanks for all the responses and will keep watching for anymore you folks may have. Jon -----Original Message----- From: Dehoyos, Ramon [mailto:[log in to unmask]] Sent: Thursday, January 18, 2007 11:42 AM To: [log in to unmask] Subject: Re: [TN] SHELF LIFE OF STRANDED WIRE Older than 2 year spool of wire should still wet with no problem. There has to be an issue, not enough heat is being used to solder the wire, or no flux to remove the top oxide layer, real cheap wire,... Of course the expose ends, specially if in a very humid or corrosive environment would have to be cut off. A freshly strip wire should have a shelf life of many years. Regards, Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Frederick Miller Sent: Thursday, January 18, 2007 12:27 PM To: [log in to unmask] Subject: Re: [TN] SELF LIFE OF STRANDED WIRE I would do a "dip and look" test to verify that the wire is wetting. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Jon Roberts Sent: Thursday, January 18, 2007 11:51 AM To: [log in to unmask] Subject: [TN] SELF LIFE OF STRANDED WIRE Searching for data or information regarding process control to self life of stranded wire (M22759/32). Wire is used for both soldering and crimping. We are considering two years from Date of manufacturing (DOM) from vendor. Problem being experience is discoloration (oxidation) of wire surface. Considering also using solderablitity criteria to determine if wire is suitable for crimping. Any help or information is extremely welcomed. Jon --------------------------------------------------- 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 -----------------------------------------------------