[Elecraft] Safe way to remove excess flux?

[David A. Belsley]

Well, Don, I didn't want to get really involved for fear of making it  
too complicated.  But, of course, you are right.  It's certainly what  
I do.  In fact, I find the process works so well that I often clean a  
given PCB several times.

best wishes,

dave


On Nov 19, 2005, at 10:14 PM, Don Wilhelm wrote:

> David,
>
> You forgot something important (it requires firewood and matches in  
> addition
> to your other ingredients) - just after the Vodka step, add:  build  
> and
> light a campfire, and dance around it chanting "flux go 'way, flux  
> go 'way,
> flux go 'way".  Do that forward and backwards ten times, and the  
> flux spell
> will surely be broken.
>
> 73,
> Don W3FPR
>
>> -----Original Message-----
>>
>> Jeff:
>>    Despite all the advice you may get, there is really only one
>> proper way to remove excess flux.  It is a long, drawn out process
>> that requires a minimum of the following ingredients:
>>
>> small horse-hair brush
>> small wire brush
>> isopropyl alcohol (100%)
>> 100 proof vodka (any brand)
>> small turkey baster
>> little leather pouch
>> butane lighter
>> a few toothpicks
>> several candles
>>
>> You can find most of these items in your local hardware store and any
>> friendly kitchen supply store.
>>
>> Place your PCB down on the counter with the trace side down.  Examine
>> carefully all top-side components to check for those that are open
>> and could trap liquid.  This might include such items as tuning cans,
>> pots, switches, connectors, and the like.  Light one candle (using
>> the butane lighter), and let the wax drip into all these components.
>> This will keep the cleaning liquids from entering and possibly
>> ruining them.  Beeswax candles are reputed to be the best for this  
>> use.
>>
>> Now turn the board over and, in your mind, map out a small section
>> (approximately 1/20th) of the board for initial treatment.  Some
>> experienced techs say that even smaller sections may be better.  You
>> might start with a section that doesn't have too much excess flux,
>> just to get the procedure in hand in a spot of little consequence.
>>
>> Using the small leather pouch, soak one corner with the alcohol and
>> place it into the candle flame (still burning).  Let the corner char
>> slightly before blowing it out.  Put a small amount of alcohol on the
>> horse-hair brush and swipe it back and forth over the burnt area of
>> the leather pouch to collect some of the carbonized char on its tip.
>> Brush this mixture onto the selected area, which has the unfortunate
>> side effect of making it somewhat darker and more difficult to see.
>> So, using the small wire brush, lightly pass it back and forth over
>> the area until the darkness is removed.  A lighted magnifier is of
>> help here if you have one.   If it doesn't come up right away, you
>> may rub a little harder.  Break a toothpick in half and use the
>> ragged ends to clear the treated area of all residue to see if the
>> flux remains.  If it does, use more pressure with the wire brush.
>> You are okay as long as you can still see remnants of the trace and/
>> or pads being treated.
>>
>> Take a swig of the vodka and continue by darkening the next section.
>>
>> Proceed, repeating all of the above steps, section by section, until
>> you have completed the entire board.  Most people feel quite relaxed
>> about the process after completing five or six sections, and just
>> about everyone I know who has tried this is thoroughly satisfied when
>> finished.
>>
>> I have still never figured out exactly what the Turkey baster is for,
>> but perhaps it is simply a symbolic souvenir for those who don't
>> simply leave the excess flux alone.
>>
>> best wishes,
>>
>> david belsley, w1euy
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>>
>