> Bev,
>
> I don't want to get into this to much, butt, I am having a difficult time
> figuring out how a hot iron could ignite such a thing.  Usually, gases
need
> a spark or flame to set them off.  That doctor must have been using a blow
> torch to do the cauterization. I think the lesson to be learned here is to
> know your doctors preferred method of fixing such anomalies.
>
> Joe Russeau
>
>
> ----- Original Message -----
> From: "Bev Christian" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, May 23, 2007 8:47 AM
> 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.
> > >
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