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Cases and ESD concerns

enigma3000

Almost all the cases I've seen for the Raspberry Pi are some kind of plastic.  So far, I've seen no mention of ESD (electrostatic discharge) protection.  Plastic would both create a static charge, and provide no protection for static discharge.  Shouldn't a case have some kind of metal shielding?  I work in the electronics industry, and where I work, we're fanatical about ESD protection (wrist straps, proper shielding, etc.).  This is my first foray into hobbiest hardware hacking in decades, so I guess I don't know what normal practices are; but it would seem dense circuitry like this would require more than plastic to prevent static damage.  What are everybody else's thoughts?

  • in reply to morgaine

    While searching for something totally different, I stumbled across this very interesting article by TI:

     

     

    Although it's written in the context of their MSP430 devices, all the advice they give there about ESD-resistent design is valid generally.  It's pretty good reading for anyone interested in good electronics design practice.

     

    Morgaine.

  • in reply to morgaine

    p. 13 of that TI document says:

       • Place all connectors and external wires on one edge of the PCB.

     

    also, there is a troubleshooting thread mentioning that touching the GPIO

    pins can crash the RPi.  Apparently the EC testing doesn't do that.

     

    http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=9006

  • in reply to morgaine

    Thanks for that paper, there was some interesting information in there.  On page 9 it mentions plastic cases, and says if there is enough of an air gap between the case and the electronics, it will provide protection; although it uses the words electromagnetic noise, which to me means EMI protection, not ESD protection.  Maybe that's a typo, I wouldn't think plastic would provide EMI protection.  Anyway, that provides some support to Michael's comments above.

     

    One concern would be, how much of an air gap is enough?  And another thing that might make it all irrelevant, is all the cables entering the case.  As the paper points out, that is also a problem; one that I don't know how you can prevent with a plastic case.

  • in reply to enigma3000

    Everything is a tradeoff, Mike, so you won't find a single perfect answer.  Whichever approach you take, you'll be trading off immunity against size and space, and that will dictate your choices.  Given a certain maximum size dictated by your situation, you'll get progressively better immunity the more you pack the available space with appropriate materials too, since air isn't particularly effective.

     

    In the end though, there's a law of diminishing returns in operation, and striving for perfection isn't really the province of engineering. image

  • in reply to Former Member

    Coder27,  Michael Kellett hit it right on the head with what i meant with "Clearly like everone said above the RPI is not intended in anyway to be suitable for Safety Critical Applications."  I have nothing against raspberry Pi but it was not build/designed with this in mind and of course the foundation is going to promote their product and encourage it in this market.  im not saying it is going to explode and harm anyone.  Im am going to state this again because i dont want to sound like im knocking the Pi,  i have one and love it but im just saying it was not designed with Safety Critical in mind.

  • in reply to Nate1616

    Thanks to everyone who responded.  I'm just going to go ahead and get a plastic case and have fun with it.