On Sun, 30 Aug 2015, ben wrote:
On 8/30/2015 6:32 PM, Tothwolf wrote:
On page 5, they describe 0.0031" 40 AWG magnet wire being reduced to
0.002" after soldering with 60/40 tin-lead solder. That 0.0011"
reduction is basically 1/3 of the diameter of the wire. This explains
the failures of the enamel wires in CHM's IBM 1620.
Copper erosion from tin is something I'd never really given a lot of
thought to, but it will certainly be something I keep in mind from now
on.
But is that the case? Would not heat induced failure be the real case
here as I suspect that a amp or two of current is flowing that now very
thin thread of wire? Digging though the doc's and a little calculation
clear this up.
My guess is that over time the thinned wires broke due to a combination of
vibration and thermal fatigue. Vibration while transporting the system to
CHM may well have been what ultimately caused them to break.
