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Durable flipflops and other counters?

Mathew

Aug 20, 2019
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How sensitive are genereally flipflops and other counters to moister, coldness etc.? I have a Johnson counter (CD4017) and I need it to withstand outdoor usage, even rain and degrees below zero. Is that possible to achieve in a reliable way? Is the best option to insulate it?
 

Harald Kapp

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Nov 17, 2011
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You'll have to impregnate your board with some kind of conformal coating or seal it by immersing it in epoxy. Standard components (and pcbs) are not suited for the operating conditions listed by you without providing additional protection.
 

AnalogKid

Jun 10, 2015
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The manufacturer's datasheet for the exact part you have will have temperature ranges for both storage and operation. CMOS devices generate very little internal heat, so you cannot rely on insulation alone to protect it from extreme low temperatures.

Beyond that, as above, most reliability issues come from the physical environment - solder quality, pc board and device pin surface contamination, etc. There are spray-on conformal coatings in a small can similar to hair spray. Acrylic is good, urethane is better.

Because coefficients of expansion for the pc board and the device package are different, temperature cycling, especially rapid changes in temperature (called thermal shock), can lead to board and trace cracking.

Is the board going to be exposed to the elements (rain and snow), or in a protective enclosure?

ak
 

Mathew

Aug 20, 2019
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Aug 20, 2019
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According to the manufacturer the minimum drifting temperature is -55 °C. It will not get below -40 °C in my application.

In order to make it withstand moisture and rain, I’ll make an enclosed environment for it by putting all the electronic components into a box and fill that box up with epoxy.
 
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