[Elecraft] Cleaning solder flux

[Larry (K8UT)]

Kester now sells a line of "No Clean" solder that leaves less residue 
than traditional products. It's not perfect (a Q-Tip and alcohol is 
better) but it's good enough for most work.

-larry (K8UT)

------ Original Message ------
From: "Dr. William J. Schmidt" <bill at wjschmidt.com>
To: elecraft at mailman.qth.net
Sent: 2022-01-02 10:12:08
Subject: [Elecraft] Cleaning solder flux

>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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