Electrostatic Discharge (ESD) Tips Every Engineer Should Know

PublishTime： 2022-07-23 Article Source：Keysight

Here are 7 tips that will help you avoid ESD damage:

Tip 0: Don't say "it doesn't happen to me"

It may be happening but you just don't know it.

All it takes is a few dozen volts to damage a device under test (DUT) or sensitive test gear. But, You won't feel a shock until it's 2000-3000 Volts.

So, you could damage or shorten the lifespan of your gear without even knowing it.

Tip 1: Use a grounded wrist strap (duh)

Why? Your body builds up a charge that can discharge into your board or your equipment. See tip 0.

It should be a high Ω path from your body to the ground to keep the current low, typically the wire has that resistance built-in, not the wristband itself. Mine is typical, with a ~1MΩ resistance:

This ESD wrist strap's cable has a resistance of about 1MΩ

Tip 2: Use grounded worksurfaces and mats

Non-grounded surfaces can inductively charge your DUT.

Your DUT can then discharge into your test gear's inputs.

So, make sure to avoid static-generating and insulating materials as work surfaces. As needed, use board standoffs to keep your grounded worksurface from shorting your DUT.

You can ground a mat into your gear if that’s an option, or into the wall outlet with a little wall outlet grounding thingy™.

Ground your workmates and ESD gear into test gear

You can ground your workmate into a wall outlet with the right accessories

Tip 3: Space it out

Keep charged materials 0.3+ meters (~1 foot) from exposed assemblies. This includes plastics, foam, etc. Anything that can inductively charge your system.

Tip 4: Discharge your cables

Your cables can hold a charge and do damage.

I thought this was crazy when I first heard about it, but you should discharge your cables before connecting them to your test gear.

This is a real thing. Here's proof.

I charged up the center conductor of a cable up to 306V by rubbing the cable sheath.

Charging up the cable by rubbing the sheath, which will inductively charge the center conductor

306 Volts on the center conductor - this could damage gear if you don't ground it first

Here's how to discharge a cable:

Step 1: Make sure your device is off

Step 2: Connect your cable to your DUT

Step 3: Attach a 50Ω shunt to the open end of the cable. You don't have to use a fancy one like this, and even a short will do if that's all you have. Doing this will ground the conductor.

Fancy schmancy 50-ohm terminator

Step 4: Remove the shunt and immediately attach the cable to your test gear

Now you can finally hook up your cable to your test equipment

Tip 5: Avoid pink foam packing

Avoid that "pink" packing material you see everywhere, it's not ESD safe and you can't trust it.

Tip 6: Cap your equipment inputs

Keep'em covered to avoid accidental zappy [insert your own "no cap" joke here. I'd do it for you but I'm not sure I know how to use that phrase yet.

Tip 7: Use ESD-safe bags when transporting boards

Carts/walking/foam can charge up! This will then inductively charge your DUT, and then we'll be right at square one.

Bonus tip:

Start your testing at the least sensitive input setting, then zoom in. This keeps you from putting too much electron juice into your gear at sensitive settings, which can be more damage prone.

Maximum voltage input on a Keysight UXR Oscilloscope

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