Wire Varnish Aging

[nlj]

Hello All,

Is anyone familiar with wire varnish aging or degradation over time? I have had failures occuring and we have come to a couple of conclusions that there are two different wire varnishes being used....a polyamide-imide and an urathane acrylate. The other difference is porosity found in the potting material.

One of the suspected issues is the wire varnish degrading over time but we are unsure as to if this happens/how this happens/ or any information on that.

Any input is greatly appreciated.

Thanks!

 

[IRstuff]

Under what conditions? Isn't it more likely that the varnish is being overheated?

TTFN
faq731-376

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[nlj]

We suspected overheating however could not get the system to reach temperatures above the wire varnish capabilities using the normal duty profile. Since I posted this we have figured out that the components were not being used per the duty cycle and it is in fact exceeding temperature.

I never did find information on the varnish degredation in my research, so I suspect that degredation over time doesn't occur enough for it to cause problems.

Thanks for the response!

 

[IRstuff]

Traditional lacquer doesn't appear to degrade much, as in wooden bowls, and magnet wire, aside from gross cracking from too much flexing.

TTFN
faq731-376

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[Compositepro]

All organic materials, including polymers, degrade with time due to oxidation and/ or hydrolysis. The rate is very strongly temperature dependent. High electric fields caused by high voltage and sharp points generate ions in the air which are powerful oxidizers.