Nick Atty wrote:


While agreeing with all of Andrew's caveats, I'd add that you can adapt
a trick from electronics and use a pair of thin-nosed pliers on the wire
to act as a heat sink.

I originally heard this back when I was in short trousers and dropping
solder on my legs in the late 60's and had my doubts it did any good
as designs using fragile germanium devices were soldered ok.

Progressing onto circuit design, development, and repair of industrial
control and communications equipment from the late 70's to the mid
90's I, along with all my colleagues, never saw ANY advantage in using
a heat shunt - fast and quick with, if necessary post transition rapid
cooling is the way to go - a heat shunt always, without exception,
slows down the process and increases the heat input from the iron that
is required to get the joint and solder up to flow temperature. Apply
it after the solder has flowed and there may be some slight advantage
but a slight wait for the transition followed by freezer spray does
just a good if not a better job and can be applied much quicker than a
heat shunt.

We regularly soldered the smallest leaded components with temperature
controlled 50W soldering irons, even a tiny 2.5mm x 1 mm detector
diode in a spectrum analyser costing 350 quid was soldered like this
(albeit with a nervous hand). Later on surface mount components were
done this way until we got our infra red rework unit and hot air
reflow guns. Our repairs were tracked for many years (certainly to my
knowledge until post 2002) and failure rates post repair were
extremely low.


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