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TL;DR: What's the origin of the 10 degrees Celsius rule?

I have heard many times that for every 10 degrees Celsius, the lifespan of components gets halved. There are many documents on the web quoting that number.

But it seems too general to be taken at face value.

When I try to find literature on the topic, I come up with two things:

  • it's either too complex for me to understand.
  • it's written by someone that understands as much, or less, than me.
  • or, mostly, it's summed up as: high temperatures are bad, buy our solution.

I believe that the truth is probably a lot more complex:

  • components have different temperature profiles with their own MTBF.
  • temperature cycles have to have an impact, at least at the mechanical level.

I am trying to answer this question:

If we average all consumer electronics:

  • does the 10 degrees Celsius rule have any validity
  • or, was it always false / without basis
  • or, was it valid a long time ago but not relevant anymore
  • or, was it based on observations in a specific context
  • or... any other scenario
Thomas
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  • So in short, you're wondering the origin of the 10C rule? – DKNguyen Aug 20 '19 at 20:33
  • yes, let me edit the question to add it that way too :) – Thomas Aug 20 '19 at 20:34
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    Does this answer your question? Or is this too complicated? https://www.electronics-cooling.com/2017/08/10c-increase-temperature-really-reduce-life-electronics-half/ – DKNguyen Aug 20 '19 at 20:35
  • That's the article that pushed me to write this question: on one side, it brings up the Arrhenius rule as the origin but concludes it doesn't really cover all failures, but on the other side, it cites a military handbook which comes up with something quite close but not the same. – Thomas Aug 20 '19 at 20:40
  • btw, I understand that reactions accelerate with temperature, whether it is from oxydation, impurities, or diffusion; what I am really curious about is the origin of the rule, not whether the actual number is 12 or 15 degrees, etc – Thomas Aug 20 '19 at 20:45
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    What is it that you were wanting to know about the origin of the rule beyond Arrhenius equation? Is that not the origin? Or do you want to know the origin of that? – DKNguyen Aug 20 '19 at 20:58
  • Apparently the article we're discussing about doesn't conclude the origin is the Arrhenius equation, but rather that it's a result that comes up from search, as well as some result from the military manual. At some point, the 10c was just 'adopted' and passed around; In the past I did car racing and there were some numbers floating around regarding $ per hp when you do engine builds; none of these numbers ever seemed to be in the ballpark, and their origins were lost to history. I'm wondering if there could be something like this, where some old manual said something and it became gospel – Thomas Aug 20 '19 at 21:06
  • "The “10°C increase = half life” rule is based on applying the Arrhenius equation, which relates the rate of chemical reactions". Your definition of conclusion must be different than mine. – DKNguyen Aug 20 '19 at 21:08
  • I believe that there have been various application manuals etc. published by manufacturers that have something like that for the life of motor and transformer magnet-wire winding insulation. There is likely empirical and/or analytical data that supports that specific application as it is stated in those documents. If the data is used as intended, it is supposed to provide a reasonably useful rough guide prediction. –  Aug 20 '19 at 22:01
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    In chemistry, we call it a rule of thumb. It gives a rough guideline, but nothing more. – Ed V Aug 20 '19 at 22:02
  • The 10°C increase above maximum temperature = half life is a rule of thumb. It is prevalent in failure of motors and transformers. This may help. [Calculating Useful Lifetimes of Embedded Processors](http://www.ti.com/lit/an/sprabx4a/sprabx4a.pdf) from TI. TI cite a 10 year life cycle increased below 105°C and decreased above 105°C. MIL-HDBK-217 is one method cited to predict reliability for mil spec designs. MIL-HDBK-217's relevance for today's electronics is questionable. – StainlessSteelRat Aug 21 '19 at 00:24
  • @Thomas Spend some *more* time with Arrhenius. Perhaps [here](https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Kinetics/Modeling_Reaction_Kinetics/Temperature_Dependence_of_Reaction_Rates/The_Arrhenius_Law/The_Arrhenius_Equation) and moving forward a few pages. It's nicely done. (There is also theoretically better-grounded work from Erying that takes reversibility and non-thermal stress into account.) – jonk Aug 21 '19 at 04:22
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    @Thomas The core for semiconductors comes directly from Arrhenius: \$\propto e^{^{-\frac{E_g}{k\,T}}}\$. Silicon's has about \$E_g=1.1\:\text{eV}\$. Use near room temperatures and find the ratio of the reaction rates. You'll see the Arrhenius factor, for example, showing up in the equation for saturation current variation with temperature (see the last factor below): $$I_{\text{SAT}\left(T\right)}=I_{\text{SAT}\left(T_\text{nom}\right)}\cdot\left[\left(\frac{T}{T_\text{nom}}\right)^{3}e^{^{\frac{E_g}{k}\cdot\left(\frac{1}{T_\text{nom}}-\frac{1}{T}\right)}}\right]$$ – jonk Aug 21 '19 at 04:24
  • putting aside Arrhenius, I view expansion and contraction as causes from CRACKING. Thus I use a small RadioShack fan to push air under my laptop, and also cool the back of LCDdisplay/backlight heatgenerator. To better cool the laptop base, I use postits ----- approx. 1cm ---- to lift up both back corners of the laptop and allow about 3X the airflow under the base. – analogsystemsrf Aug 21 '19 at 05:52
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    When I design PCBs, I'll compute the total heat that must be removed, and keep in mind the thermal resistor of ONE SQUARE of standard PCB foil ---- 70 degree Centigrade per watt of heat flow. Place the hot components NEAR THE heat-extraction-mounting-bolts. – analogsystemsrf Aug 21 '19 at 05:54

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