Hey Hivemind. I am curious if anyone has experience with the long term aging effects of electronic components.
I’m looking to gather information for my team so we can put together design guidelines for aging.
What happens to resistors over 5 years? How about 20 years? Are there rules of thumb or better yet, calculations for aging?
No expert here, but temperature has a big effect. Look up “Arhenius”. The faster the chemicals react, the more aging occurs.
There are some military and telecom models for component aging under different types of stress from sitting inactive in a quiet room to being shot out of a cannon or in space.
Bellcore/Telcordia is the telecom version, they’re pretty picky about having long mean time between failures just due to the sheer number of parts they have running and the difficulty in fixing some of them (undersea cables).
MIL-HDBK-217F was another standard that I’ve heard of, it’s old but available as a free PDF.
When we were trying to get a telecom part certified we had to run batches of them in ovens for years, the heat would accelerate the aging so you could get a couple to fail at different temps and try to fit an exponential function to the accelerated failure rate that could be extrapolated back down to room temperature.
Yeah I have read through the MIL-HDBK-217F. It seems to be deemed obsolete and the last revision was sometime in the 90s.
I may need to adapt the concepts in it to something we can use.
It’s been a while since I looked at 217F. But the basic math is still valid today. The issue is that many of the coefficients used don’t match modern material sets. (At least, that was the case with capacitors.)
Related, the material set matters most to whatever component you look at. Because it is me, I know capacitors better than other components.
For example, the aging effects of ceramic dielectrics differ from aluminum electrolytics.
The “aging effect” of Barium Titanate ceramics is them losing a few percent of capacitance every decade-hour, but the effect isn’t permanent. It’s a physical change as the molecule changes shape. In contrast, wet-electrolytic capacitors have an aging effect that leads to parametric failure because the oxygen in the electrolyte gets consumed.
And since @David_Vandenbout brought up Arhenius, I’ll just point out that Polymer-Tantalum caps have an estimated functional aging rate in the thousands of years… as long as you don’t reflow solder them. 
[Also, side note, the aging rate of the epoxy used to encapsulate Poly-Ta caps is only in the hundreds of years, lol.]
James, want to come back on the pod to talk component aging?
Back in time, I attended a reliability seminar held by Martin Shaw from the UK. It was most excellent. I am sure he would have to say some words about aging as well.
He would also be a good one for the podcast ( I am looking forward to the future episode with James as well )
PS: Are you building Voyager 3?
Yeah here is a picture of our lab 
What exactly is “aging rate”? I googled it but didn’t find anything.
Interestingly, I did find this which mentions how capacitors can be “de-aged” by raising their temperatures above 150ºC. That’s exactly the opposite of what I would have thought.
Again, the effect is different based on the material construction.
The “aging rate” of ceramic capacitors is how much capacitance they lose over time. It applies more to Barium Titanate (Class II and III) dielectrics than it does Class I (especially those made with Calcium Zirconate.)
When barium titanate is exposed to its curie point, the molecule changes shape. The orientation gives it a higher permittivity. However, as time passes, the molecule relaxes and causes the permittivity to drop.
So, the effective capacitance drops over time. It is a logarithmic scale. A few percent after an hour. Then another few after 10 hours. Then 100 hours, etc.
Murata has some FAQs with good pictures (but not a good way to link to them): Search Result | FAQs | Murata Manufacturing Co., Ltd.
Unlike other ways “aging” gets used, this change in the ceramic material isn’t permanent. As you found, if the capacitor is exposed to its curie point again, then the aging clock resets.
Regarding Polymer-Tantalum, their construction doesn’t have the same kind of effect. Their parameters change over time but not because of a natural effect like Barium Titanate—instead, the polymer oxides which increase their ESR. Or the Tantalum can crystalize and puncture the dielectric layer. Both of those changes are accelerated with energy, especially heat energy. So, Arernius works very well in their case. And it is where the operational life is estimated in the 1,000+ year span.
And for a third comparison. Wet (traditional) aluminum electrolytic capacitors also have an effective aging rate. In their case, the rate at which the electrolyte is consumed “ages” them. (And, coincidentally, during manufacturing, al-electrolytics go through an “aging phase” where voltage/current is provided to allow the dielectric to self-heal.)
Haha. I’m not an expert in the area, but I could put together some thoughts to share. And talking with you guys is always a blast.
It’d be a chance for me to share one of my favorite bits of reliability trivia: what does “rated voltage” for a capacitor mean, and how is it determined?
The answer will shock you!
(Unless you read AEC-Q200 or other qualification plans.)