Aging Electronics

RRRitchey

Smart-Fly
Hi,
I had a pilot call me today and he had bought a PowerExpander Eq10 at a swap meet recently. He installed it but found that if he flexed the unit that it was intermittent. This brings up something that we should all think about. Care and feeding of our electronic equipment. One thing you should realize is that the material printed circuit boards (PCBs) are made of, typically FR4, is sensitive to humidity. High humidity can cause the FR4 to swell and warp. This can cause micro-fractures in the joints between the IC legs and the pads on the PCB. I think this may be what this pilot was seeing, the Eq10 had been stored in a high-humidity environment and when he brought it into his shop it probably released some of the water vapor. So, what I am saying is you should try to store all your electronics in controlled humidity environments. Short exposure to high-humidity is not a problem but storing your electronics in high humidity for months and then going back to a dryer environment will cause all your PCBs (receivers, servos, etc) to swell and then shrink. The connections between the current generation ICs and the PCBs is so small that expansion and contraction can cause problems over time. The new lead-free solder (as mandated by RoHS in various countries and now used in all manufacture of electronic equipment except military equipment) is not as tolerant of this behavior as the old leaded solder was. And speaking of lead-free solder, the other reason lead was added to solder was to eliminate an issue called "whiskers" (http://www.nbcnews.com/id/21151552/w.../#.UUHspzdc1Kg). Tin will spontaneously start growing whiskers which can bridge the space between pins on an IC package and eventually cause a short. Some of the failures in the Toyota throttle control issue were traced back to tin whiskers growing on the IC pins. The whiskers tend to grow in high electric fields so any place you have higher voltage or higher currents they are more likely to grow. The basic idea here is that your electronics are not going to last as long as those manufactured with lead based solder so you should keep that in mind when keeping receivers and servos 10 years. Most lead was abolished in electronics manufacturing around 2002. Anyway, I hope this sheds some light on electronics life issues and how to store your equipment.
 

BRUTUS

Plank Junky
Lifetime Supporter
I had no idea this problem even existed. I've been reading up on it the last couple hours, and this phenomena has killed satellites, people, missile guidance systems, nuclear reactors... And soon our planes!

http://nepp.nasa.gov/whisker/background/index.htm

Bring back the lead!
 

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psycho-patch

Well-Known Member
RRRitchey, thanks for posting the info!! I had completely forgotten about the whisker growth. :thumbsup: :thumbsup:
 

Classclown

Well-Known Member
WoW, I'd heard of this, but never gave it much thought, I probably got distracted from the articleand never got back to it. Thanks ADD...
 

earlwb

Active Member
A lot of people never pay any attention to the On/Off switches they use to power their flight packs either. Many of the mechanical switches actually wear out over time. Even faster with high vibration modes too. The little dual slide switch is notorious for going bad after a while. The solid state switches that have a fail on feature have no moving parts inside and last a lot longer. But even these solid state switches can fail eventually, but with the fail on feature at least you know it before it is too late.
 
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