deskthority

I'm working on a new keyboard with a plastic (POM) case. Is electrostatic discharge an issue? If so, what measures are taken to prevent damage to the electrical components? I'm not referring to the construction process but it's actual usage.

Almost all electronic parts have EDS protection built in up to 2 kV at least. Human body model. I doubt you need more.
As for as ussage: do not touch the metal parts of the keyboard USB connector when you suspect you may be charged. Touch a ground wire of your electrical outlet first.

Thanks vvp for the piece of mind. That's good to know.

Everything metal in the keyboard should be grounded.

It's 8kV, but MCUs usually require 100R resistors as close to GPIO as humanly possible to actually pass the test. dI/dt is what kills.
I'm not a real EE, but I've read a lot of datasheets recently. So, not a legal advice, but..

Not an issue in practice (not a single GPIO of mine died by ESD) - but if you're extra paranoid - cover internal case surfaces with graphite and make sure that graphite layer is connected to ground. The resistance of that layer will be huge - but it will still be a preferred current path to the ground.

If you're really REALLY paranoid - I have a word for you: Aquadag.

Interesting. Application notes I read recommended to place EMI and ESD protection (diodes and low pass filters) as close to the source as possible (i.e. near the edge of PCB where signal enters). Only power distribution network requires also decoupling capacitors and those should be as near to the MCU as possible.

Also an additional 100 ohm resistor in series sounds strange considering that human body model already has a resistance of 1500 ohms there. Maybe because a small shunt capacitor can be over the 1500R resistor which may be included there to simulate parasitics?

Sorry, shouldn't have posted late at night. Yes, 100R and TVS diodes at periphery, bypass caps as close to IC as possible.