jim rozen wrote:

In article , Daniel A. Mitchell says...


Perhaps, but solder work-hardens ... a LOT.


I don't think that alloy shows work hardening.

Jim


Agreed that the term 'work hardening' (in a metallurgy sense) was ill
used. Fatigue would be a better term.

What I meant was that it loses it's ductility, fatigues (crystallizes)
under flexure, and loses it's integrity to such an extent that the joint
fails mechanically (as well as electrically).

The composition of the particular solder used has a lot to do with this.
High lead solders fatigue more than high tin solders. The addition of
some silver can increase the ductility.

Many solder joints can be disconnected by merely flexing them a few
times. Add heavy components, ill mounted and free to move around
(including the cables themselves), and the joints will likely fail due
to fatigue. That's the reason for the strong mechanical mounting of all
components including the cables ... it relieves the sensitive solder
joint of much of this strain, flexure, and vibration.

As stated, the much less massive components now used, as well as PC
Boards and other modern mounting techniques, have greatly reduced the
need for such strong mechanical mounting. It was the norm for most good
soldering circa W.W.-II however.

Dan Mitchell
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