[Elecraft] Organic Rosin Core Solder

[Jim Harris]

Hi,  the following are some thoughts that may explain
and perhaps help.

Looks like what is being referred to is "water soluble
flux."  It's primary use is in the mass production of
PC boards on commercial wave soldering machines. 
Discrete components are first either manually
place/inserted or pick and placed by computer
controlled equipment.  Next the boards are placed on a
conveyor type arrangement that passes the board over a
rolling (wave) bath of water soluble flux.  This coats
the entire bottom of the board.  Next the board passes
over a rolling (wave) of molten solder which actually
solders the entire board in a few seconds.  As the
boards are passed thru the system a giant heating
system immediate above the board preheats it to
facilitate solder flow.

After the board cools for a few short minutes it goes
into the equivalent of a commercial dish washer that
washes the water soluable flux from the board.  Those
boards being used for critical applications frequently
get two washings.  

Hand soldered boards are usually put thru an elaborate
"degreaser" process.

Yes, water soluble flux will cause numerous conduction
paths throughout the board and some corrosion as
mentioned.  (I can tell you a horror story about
improperly washed boards in critical medical
equipment.)  High ambient atmospheric moisture can
cause recurrence of conduction mixed with a slight
elevation in ambient heating greatly exacerbates the
problem.

Simply desoldering and resoldering each component will
not correct the problem.  The flux must be completely
removed.  Proceed at your own risk, but as suggested
earlier thorough washing with warm water with lots of
scrubbing would be my thought.  I'm note sure how
water resistant all the components on the Elecraft
boards are.  Most resistors, dipped capacitors and
IC's should be okay.  But, again not guarantee.  A
major part of choosing components for commercial PC
boards that are to be wave soldered is considering
their reaction to wave soldering including repeated
washing.

Perhaps this has been a bit of help.  Good Luck

Jim, AB0UK
K2 SN 4787




		
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