Author Topic: Is it possible to mod a non ESD-protected PCB to give it ESD protection?  (Read 1797 times)

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Offline perry4761

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  • Posts: 36
I bought a full brass keyboard and bought the optional PCB to go along with it, because I figured I couldn't be bothered to source one that would match the plate and the location of the USB-C opening of the board I got. Little did I know, non-ESD protected PCBs are still a thing in this day and age :eek: I wonder if there is a type of film or something that can be applied to the PCB to give it at least a moderate amount of protection against ESD? This board is full metal and I don't want to worry about the PCB dying on me every time I touch the case to move it :(
Mechs are not a hobby, they're a god damn addiction.

Offline Tactile

  • Posts: 1291
  • Location: Portland, OR
The best protection is grounding. Make sure everything is grounded. You may even be able to run a wire from the ground plane of the PCB out to a ground point. You aren't trying to block the ESD, but to re-route it to ground.

There's some good info here:

https://www.elimstat.com/2017/04/20/how-to-use-anti-static-mats/

Offline RichardH

  • Posts: 35
If there's room and you're good with electronics, you can try and make a board to intercept the usb signal pins. However, In my experience, the ESD components are tiny (like 1mmx1mm) and bloody difficult to solder by hand. I've actually had a lot of failures in designing DIY kit stuff with them, since they're often parasitic/corrupting to the signal if not routed in the perfect way. They often involve even tinier support components like 0402 or 0201 caps/resistors.

There are standalone USB isolator dongles, but in the end, it's going to have to plug into your keyboard with a cable, so the net value is pretty low. I think having a huge chunk of metal around your board is probably going to help dissipate the charge, especially if it's connected to the USB ground.

If it's all hot swap, then I'd just say buy a backup PCB if you're using the board in a place that's highly affected by static electricity. The only thing that a USB ESD chip is going to solve is reconnection spikes. Just moving the board around on your desk without disconnecting shouldn't be a problem.

-Rich

Offline jamster

  • Posts: 718
  • Location: Asia
? This board is full metal and I don't want to worry about the PCB dying on me every time I touch the case to move it :(

Would this be mitigated by the circuit board presumably being isolated from the metal case? I'd expect grommets or some other insulator to be in place. If so then static risk should only exist when you plug the USB cable in.

Offline Leslieann

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Would this be mitigated by the circuit board presumably being isolated from the metal case? I'd expect grommets or some other insulator to be in place. If so then static risk should only exist when you plug the USB cable in.
No, in fact that can make it worse.
In this instance the pcb is grounded but the case isn't, electricity chases ground, so even if it jumps to the case it can jump to the pcb after. More than once I've seen sparks jump nearly 1/2in which is more than enough to jump to the pcb from an aluminum case.

You need to ground the case to the grounding wire (I also connect it to the shielding) on the USB so it gets directed away from the pcb.
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