Flux removal question

[Scott Gravenhorst]

I used to repair VDTs at the LA Daily News.  We did exactly what
Harry describes (under a sort of fume hood) and it worked 
exceptionally well.  I don't have a clue anymore though as to
what the chemical nature of the stuff in the can was.  All I know
is that two passes with it and the toothbrush thing made the
board as "clean as a whistle".  Whatever the stuff was, it didn't
melt the toothbrush bristle or handle.  It was rather light and
evaporated fairly quickly.

Harry Bissell <harrybissell at prodigy.net> wrote:
>I like to...
>
>1) remove any flux I can with a sharp pointed object, like an
>awl or x-acto knife. If you are scratching the PCB, or soldermask
>you are using too much force. The flux I use cracks away like
>hard candy. It has a sticky or gummy consistancy after that.
>
>2) Remove the flux with an old toothbrush... this gets all the mechanically
>removed flux off.
>
>3) hold board at an angle and spray, so the remains of the flux can
>flow downhill and be carried off the board...
>
>4) Use the toothbrush again (I use a different one for this stage) if
>there are any tough spots.
>
>5) Final rinse with the spray..
>
>Other ideas... use a water soluble flux and a dishwasher... (I don't know if
>I want to wash the PCB and the bowl from my Rice Krispies  at the same time....)
>
>or use "no-clean" flux.   I have not done either one yet. I still have about a
>5yr. life on my
>current roll of flux solder...
>
>DON'T mix water soluble and standard flux on the same board. They don't like
>each other and you will make a major mess !!!
>
>H^) harry
>
>Paul Wilkinson wrote:
>
>> Here's another flux removal question - How do you do it?  Do you just spray
>> it on and let it dry, or do you have to get in there with a Q-Tip?  And do
>> you need to do it soon after soldering?
>>
>> My flux remover came with a billion warnings all over the can AND another
>> sheet of warnings attached with a rubber band - but no instructions!
>>
>> - Paul
>>
>> ------Original Message------
>> From: Harry Bissell <harrybissell at prodigy.net>
>> To: Blandon Ray <arp2813 at home.com>
>> Sent: June 18, 2000 3:54:03 AM GMT
>> Subject: Re: Flux removal question
>>
>> You seem to be right on target. I would avoid flux cleaner on
>> 1) Polystyrene caps
>> 2) Pots and Switches (it will remove lubricants etc...)
>> 3) Jacks  (could leave a residue...)
>>
>> I washed my PCB before installing these components.
>>
>> Flux leakage can be a problem around high impedance areas like the VCOs,
>> S/H etc.  I usually try to scratch the flux away with an x-acto knife (gets
>> brittle
>> after about a day, flakes off easy) then clean with a swab.
>>
>> Your caps might be OK and they might be toast. Can't tell if they are
>> damaged
>> until you fire it up. I'd try first...they might be fine.
>>
>> H^) harry
>>
>> Blandon Ray wrote:
>>
>> > Actually a few questions, especially for those of you building the Mini
>> Modular:
>> >
>> > After last night's round of soldering I sprayed the back of the board with
>> some
>> > flux remover. When it dried, some of the clear plastic polystyrene
>> capacitors had
>> > turned white on the outside. My questions are: first, is this likely to
>> damage the
>> > caps themselves? Second, what else shouldn't I spray with flux remover?
>> Finally,
>> > how important is it (generally speaking) to remove flux from analogue
>> circuits?
>> > I'm told it can cause problems related to current leaking around the
>> board, but
>> > that's about all I know.
>> >
>> > Thanks in advance,
>> > blandon
>>
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>

-- Scott Gravenhorst
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