That report on the Magazine was probably around April 1st No? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian Sent: Wednesday, May 23, 2007 8:47 AM To: [log in to unmask] Subject: Re: [TN] Flux residue, burnt flux NTC I would be careful with the latter use of a soldering iron! A well known gastro-intestinal specialist came to the medical school at the University of Toronto and gave a very enlightening presentation on farts. (He generally called them anal emissions.) He said there was one case where they had been doing surgery in that general area and the anesthetised patient passed gas as they went to cauterize and the resulting explosion blew the surgeons back against the wall and tore a 5 inch gash in the poor fellow's large intestine. They had to do emergency surgery and the guy woke up a tad sorer than he expected. I read this in the Canadian edition of Time Magazine and it made such an impression on me I have never forgotten it. Bev -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Wednesday, May 23, 2007 8:38 AM To: [log in to unmask] Subject: Re: [TN] Flux residue, burnt flux Quite often, the small amounts of burnt flux or other particulates are from using the solder irons to perform operations they were not intended to do, such as shrinking tubing on wires, conformal coat removal, epoxy removal, performing artistic designs in wood while the boss is not looking, hemmorhoid removal........ -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis Sent: Wednesday, May 23, 2007 2:38 AM To: [log in to unmask] Subject: Re: [TN] Flux residue, burnt flux I'm sure that an eminent co-contributor to this forum will tell you, "it depends". If the flux is truly burnt, i.e., black, this indicates pyrolysis, which is a fancy word meaning decomposed by heat. Pyrolysis indicates that the residues have split apart into numerous compounds, leaving carbon-rich stuff. Elemental carbon can be an electrical conductor; do you want conducting particles in your assembly? They may appear fixed in place now, but will they remain so during the life of the equipment? More important, WHY are they there? It may be because the operators don't keep the bits of their irons clean. Do they wipe them on a wet sponge before each joint is made? It may be that the time/temperature conditions of the joint being made are far from optimal. It may be lack of adequate training of the operators. I can't tell. Whatever, prevention is better than cure; a lttle research into the causes may give you the answer. As to flux flow, maybe your solder wire simply has too much flux. Some manufacturers allow you to choose the percentage. Yes, it is easier to solder with an excess. It's a compromise. What you have not told us is the essential information: what kind of assemblies are you making. You can obviously be more tolerant of imperfections if you are making toys than if you are making inertial guidance or satellite systems. Probably you are somewhere between thes extremes. "It depends"! Brian Sue Powers-hartman wrote: > We fight a constant battle with operators leaving burnt flux in > joints. Maybe only a small speck, but drives the inspectors nuts. The > way I read JStd-001D, if they can not see it at referee inspection power, they have to accept it. > How dangerous is this burnt flux to the PWB? If it's not seen at > inspection power and left on the board, what happens. Also, what about no clean flux? > Our solder training video says that if no clean flux runs out to far > and is not heat activated, it can cause problems. Operators watch this > video, but somehow do not get this. They say that it's no clean, they can leave it all on. > I keep saying that this can be a problem, and then they ask me, how > far out can the flux be away from the joint before it's unacceptable. > > Wow, I'm glad I found this forum, I have so many questions to ask you guys. > Anyway, thanks for the help on this subject. > > --------------------------------------------------- > 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 ----------------------------------------------------- --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. 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