Do antistatic gloves help avoiding ESD?

Question

On page 11 of this ESD Book:

ESD sensitive device can experience a damaging discharge if touched by a person, even if that person is properly grounded. Increasing the electrical path's contact resistance is one way to control the speed of the discharge. A good way to accomplish this is by wearing static dissipative cots and gloves.

I thought antistatic gloves are not being used to avoid ESD, but to avoid fingerprints on electronics and whenever you want to wear gloves for that purpose, these gloves should be antistatic. Otherwise they can cause ESD.

Yes, ESD is a point-of-contact thing, but can antistatic gloves reduce ESD?

Answer 1

You are right. If you wear gloves, they should be sufficiently conductive so that their surface does not retain a charge, which gets discharged through you to your connection to ground.

The purpose of all ESD precautions is to get everything at the same potential. It doesn't have to be 'ground', but that is the most convenient level to choose. So insulators have no part in this, they allow potential differences to exist. Conductivity is what's needed. If you need to use a glove, to protect components from skin oils and salts, then wear plain cotton. The cellulose fibre they are made from retains some level of moisture (there's no magic to being 'natural') which renders them slightly conductive, sufficiently so for ESD protection purposes.

Conductive gloves will not work for ESD protection by themselves. They need to be used as part of a full system that includes getting you, your worktop, your tools and all components at ground potential, and keeping them there. Wriststrap, conductive benchtop, both connected through safety resistors to a common ground are needed. Tools and conductive bags and tubes get grounded when placed on the bench or handled by you.

While it's true that adding extra resistance in series with you will reduce the level of current that flows from a charged you into a device, it's not the right way to do it. The right way is to avoid you being charged in the first place. Think of insulating gloves as seat belts / airbags, and not being charged in the first place as driving so you don't crash into things.

My heart sinks at work when a colleague approaches me, holding a circuit board that's intended for me, that's not in a conductive bag. Often they are gingerly holding it by some insulating part, apparently knowing there is an issue, but not knowing what to do about it. I make a point of touching them first to minimise the ESD problem they have caused, male or female, intern or CEO. Get at the same electrical potential, then pass the sensitive item. If it was insulated from them, then I find a large ground feature on the board, connector shells for instance, and take it by that, so that any current flows to a robust rather than sensitive part of the item.

This error happens because people do not understand the number 1 goal of ESD protection, everybody and everything stay at the same potential. People peddling insulation, or denying that charge accumulates on an insulated person, do not help.

Unfortunately, ESD unsafe practices are just that, unsafe, they do not guarantee failure. In fact, most people employing unsafe practices will get away with it all the time, and all people will get away with it some of the time. This means that failures are rare, and difficult to identify with specific times when they occurred. In industry, we need all the people to be working safely all of the time, which is why there are working practices which can at times seem a little draconian.

Answer 2

They do provide an effective way of preventing ESD because they insulate the devices you're touching from your charged fingers. Since the ESD normally won't be strong enough to arc around or through the rubber, they're generally effective.

However, there are some downsides to them:

1. They don't actually help dissipate your static charge, so if you bump a component with your forearm or other body part, you'll still get ESD.

2. I've found them to make it difficult to manipulate small components and tools.

I would recommend a good ol' anti-static grounding strap instead. They don't interfere with your fingers, and they actually dissipate the static charge you build up, so if you bump a component with a different body part, ESD will still be effectively prevented.

Epilogue
I've done some more research based on the other answer and comments, and it appears I was probably using a really cheap set. It looks like they're more commonly made of nylon and other materials that actively help dissipate the charge rather than just act as a resistive barrier. I still stand by my recommendation though: it's still better to prevent yourself from becoming statically charged in the first place, and I find that working with bare fingertips is almost always easier.