Re: Cleaning Solutions for PC Boards Advice

["pwillard" <petewillard@hotmail.com>]

Hmmm, No flux left over?

As a former wave solder operator, I beg to differ.

There remains, after wave soldering, a small amount of flux, sine the boards
were carried through a flux wave as well as a solder wave.

Many of the far east pcb manufacturers like to skip the flux cleaning stage,
but you don't need to do much work to clean them.  Some of  the more
environmentally friendly board cleaners are water based and introduce no
corrosion issues. For a quick clean up job, my favorite choice is a mixture
of Isopropyl Alchohol and Ethanol. (I miss Freon, too bad it was an ozone
depleter.)





"Michael J. Mahon" <mjmahon@aol.com> wrote in message
20020217143257.29371.00002475@mb-fc.aol.com">news:20020217143257.29371.00002475@mb-fc.aol.com...
> Linards Ticmanis wrote:
>
> >Bryan Villados wrote:
> >
> >
> >> I was reading a guy's technique for cleaning printed circuit boards of
old
> >> Apple II hardware. What he does is he takes the boards out of its
cases,
> >> soaks the boards into a solution of de-ionized water and alcohol, then
> >blows
> >> them dry with an air gun. Is this good advice? If so, what's the
formula
> >for
> >> this (X parts de-ionized water to X parts of alcohol)? And how long do
you
> >> leave the board sitting?
> >
> >In my (albeit limited) experience, water is only needed if there is lots
> >of flux leftovers from soldering. For grime and dirt, cheap denatured
> >alcohol, some detergent, and an old toothbrush is the right mixture.
> >You'd want to remove socketed ICs first, especially if they have
> >stickers on them (e.g. EPROMs). This mixture shouldn't harm
>
> All readily available alcohol products contain water--it is difficult and
> expensive to remove completely.
>
> Still, used sparingly (brushed on and wiped off) there should be no
> problem, as long as only sealed components are involved.  Be very
> careful of getting liquid solvents around switches, pots, or variable
> capacitors, since they will mobilize contaminants and deposit them
> where you don't want them inside the devices.  IC sockets are a
> special case, since there is considerable friction when re-socketing
> an IC which does a pretty good job of cleaning the contact surfaces.
>
> You must have a different kind of flux where you live.  Here in the
> USA virtually all electronic-grade solders use a rosin flux which is
> virtually waterproof.  Since there should be no flux residue from a
> professional wave-soldering, I assume that we're talking about flux
> remaining from some "amateur" after-manufacture soldering, and
> it should all be non-conductive rosin.  In the USA, the most common
> water-soluble flux is ammonium chloride, which is _absolutely
> verboten_ for anything electrical or electronic, since it is hygroscopic,
> conductive when moist, and corrosive.  It's fine for gutters.  ;-)
>
> It is unnecessary to remove rosin flux from finished work except
> for esthetic considerations.  If it is to be cleaned, a professional
> flux solvent should be used, and all the caveats above regarding
> solvents and PC boards apply.
>
> If you just want to make the board look better, just brush it with
> a soft, dry brush, possibly with the use of air.  If you are trying
> to clean off some contaminant, like peanut butter or dried Coke,
> you'll have to go the solvent route, with an appropriate solvent
> and/or detergent.  When the board appears clean, rinse the area
> multiple times finishing with a couple of deionized water rinses.
> You can hasten drying times by a final alcohol rinse (but try to
> avoid the common "rubbing alcohol", which typically contains
> some oil to prevent excessive drying of skin).
>
> Final word:  don't do anything with liquids unless a) it's _really_
> a mess and must be cleaned, or b) you are willing to make the
> board non-functional or significantly less reliable.  Esthetics
> are not a good enough reason to soak a board!  If you just
> can't resist, use careful "spot" cleaning.
>
> If it works, don't fix it!
>
> -michael
>
>  Email:  mjmahon@aol.com
>  Home page:  http://members.aol.com/MJMahon/