[Elecraft] Cleaning solder flux

[Dr. William J. Schmidt]

During my under-graduate and graduate school careers, I worked at
Honeywell's circuit board fabrication shop for about a year and a half.  We
had two machines in the shop that dealt with flux: a reflow machine and a
parts set machine.  The reflow machine was used to reflow the solder after
plating so that it looked shiny.  The board was emersed in a 601-type flux,
heated to about 425F, cooled down, and then scrubbed (brushed) with
Isopropanol alcohol three times (stages) with a water rinse and force-air
dried (all automagically).  The solder was beautiful and shiny at the end of
this process.  The parts-setting machine was similar... the whole
(pre-reflowed) board was fluxed, the parts set, heated, and then cleaned.
All fluxes come off with Isopropanol alcohol (remember IPA is polar like
water and works that way).

 

Fluxes come in various forms... some are more corrosive and some not... so
you should follow the directions (right off the website).  Rosin can remain
on a board, but also can be problematic because it can collect debris (dust
and other unwanted materials) because its plastic (flows at room
temperature) sticky.  Many of the water-soluble fluxes are more acidic, and
will tarnish the solder joints if not removed.

 

On the subject of using water on electrical components... most components
(particularly if they might be mil spec) are made for water emersion (NOT
ALL!).  In my office lab we routinely clean circuit boards by scrubbing them
with just water and force-drying them.  Works fine.  About a decade ago, I
used to buy up surplus AM/ broadcast band transmitters for repurposing to
other countries (mainly south America) for the Christian broadcasting
markets.  Once back at my shop, the first stop was a good through power
washing in the driveway (paper and other water damaged goods removed of
course) followed by a good drying (leaf blower).  Works fine!

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
VP2EHZ

 



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