jim rozen wrote:
In article , Lloyd E. Sponenburgh
says...


They always taught us in electronics schools, "Make a secure mechanical-wrap
before soldering; solder isn't glue."


Oddly this is actually incorrect. Yep, they taught the wrong
thing, but it is so widely accepted nobody ever questions the
mil-spec 'wrap three times before soldering' approach.

To convince yourself otherwise, make a simple lap joint using
stranded wire, with the lap being only two or three wire
diameters. Copper wire of course.

Then tension the joint until it fails by pulling on the wire
ends.

The joint does not come apart, even with standard 60/40 lead tin
solder.

Jim


Perhaps, but solder work-hardens ... a LOT. If the joint is subject to
even slight vibration or flexure, the solder-only joint will eventually
fail. Maybe sooner than later. The reason for the mechanical connection
is to rigidize the joint before applying the solder. Then the solder is
NOT subject to excessive flexure.

This has become less important in most modern electronics, where the
solder joints have little mechnaical strain applied to them (due to the
tiny size and weight of many components).

Similar things can be said for corrosion and thermal expansion in the
solder joint.

Dan Mitchell
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