Emc issues for electronics housed in a plastic box

Stick a CE mark on it. Copy someone else's declaration of conformity. That's what everyone else does. You'll be fine.

Unless you're making a *really* screwed up circuit or a transmitter of some sort, the chances are it would pass tests anyway. And nobody bothers checking.

This opinion is both true and worth what you paid for it.

Search for a thread a few weeks old which covers the basics of ESD protection. The thriving business in compliance engineering and independent test labs suggests that the poster who claims that no one is really making efforts to comply is exaggerating, although I agree that many products don't comply. Paul Mathews

There are some (expensive) conductive plastic boxes available, usually "available in any color you want, so long as it is black". Or, if for production quantities, have them coated inside with Acheson electrodag or equivalent; they have one or two that are not only conductive but also dissipative (Nickel Carbonyl if i remember correctly). Lastly, for onesies, line the inside with aluminum foil from the kitchen, or conductive copper sticky tape (either the 3M crinkled "RFI" finish or the plain flat stuff sold to get rid of garden slugs).

Make sure the MCU is well decoupled, the power supply is current limited ( to avoid latchup problems) and make sure you use the watchdog - this should give reasonable protection against ESD. About the only major risk is when the connectors get plugged in - make sure all the shells are well bonded together, and tracked in such a way as to avoid coupling transient currents into your circuit.

all the shells are well

currents into your

If you do this by bonding the ground contacts of all connectors onto a ground plane covering most of the board area you will also greatly reduce rf emissions.

John

Thanks for all the replies, I have got a lot to go on this morning!

regards

IanM