Thermal fatigue of electrical components. 1

[mwmonty]

I am currently working on an RCFA of an electrical cabinet that is having premature component failure due to thermal fatigue. I have heard in several training courses that an increase of 10 degrees C will result in a decrease in electrial component life by 50%. However, I am having problems locating a reference that I can use to support my investigation. If anyone knows of a online reference I can use, it would be of great help.

MWMonty

 

[IRstuff]

The general Arrhenius equation includes a term that is called activation energy in the semiconductor industry and basically describes the slope of the curve of lifetime as a function of temperature. The 50% rule applies to certain failure mechanisms that have an activation energy around 0.5 eV.

There are other failure mechanisms, particularly in semiconductors that hvae activation energies over 1eV up to 1.5 eV, which allows you to test part lifetime using accelerated temperature.

The MIL-STD-883 life test qualification testing uses this principle as the means of certifying that the military IC meets a certin range of reliability and lifetime.

TTFN

 

[cuky2000]

Does any one know if the Arrhenius equation applies to loss of life of insulation with the moisture content?

This do not appear to have direct relation with the 10 oC rule, but the following statement from a technical source has so much similarity that call my attention: “Each time the moisture is doubled in a transformer, the life of the insulation is cut by one-half”

Since moisture accelerate the degradation of insulation, I suspect that this chemical reaction could be explained by the Arrhenius equation or a similar mathematical model.

Any reference or Internet link in this subject will be highly appreciated.

Thanks.

 

[IRstuff]

The Arrhenius relationship is a mathematical model of a rate process. As such, it's used in chemistry, reliability, etc, WHEREVER, there is a exponential relationship of some process with some independent variable characterized with a single equivalent activation energy parameter.

TTFN