esdprotectiontvs
I'm wondering why I don't see ESD protection for ground (can you even protect ground from ESD?) – If there is a large electrostatic discharge straight onto the ground plane wouldn't that voltage spike of the ground level damage all the electronics using that ground ? Wouldn't it be the same as zapping any other pin of the IC with a huge voltage spike ?
Thanks in advance!
The people that do testing and manufacturing at our company use antistatic wrist straps and ESD mats when handling potentially sensitive electronic components. There are also ESD floor mats available.
As Johnfound already pointed out, most devices are pretty resistant. But if you make ESD protected handling part of your production flow, you can be pretty sure that defects that occur during product lifetime are not the result of pre-damaged components due to ESD.
Here is the general approach you should take.
Any connectors and contact points to the outside world should have protection. The outer perimeter of the board should have a guard ring running around it with protection on it. This is because people tend to handle the board by the edges. This guard ring should be the ground for the rest of the system with a another ring concentric just inside.
All other internal nodes probably can't be protected, in fact bare boards are never considered to be ESD proof for all possible scenarios.
You can encapsulate the board to provide a little more protection, depending upon the encapsulation it can be quite good. 32 um of parylene would really help but is expensive (this is a mil standard).
But ultimately, the whole board should be inside of an enclosure to prevent contact and discharge.
Best Answer
It could, if the current was extremely high or the layout was bad.
I saw a device (a data drive plugged into a computer) some years ago, and it was being used on a circuit connected to the mains- risky at the best of times but it was nominally okay. Due to sloppiness and rushing, the ground lead wire on the drive (a braided wire with a ring terminal, flapping around) accidentally touched the "hot" which vaporized the trace to wall plug ground but there was still a capacitor from the now 120VAC node to +5V, which blew out every single chip in the drive and the computer. It also caused a potentially dangerous voltage to appear where it shouldn't. Ideally that would have just blown a circuit breaker or tripped a GFCI.
Less catastrophically if there is a path to ground from an external terminal that is not direct, but passes through other circuitry, glitches or even damage are possible from ESD.
Beware of current paths that may exist through your design where current is not limited in some way.