Winter Static Is Back on the Line. Check the Hands First.

Every November the same two things change on an electronics line. The heat comes on, and the humidity in the building drops toward 20%. Somewhere in that same stretch, the hands of the people building your boards start to crack, and nobody connects the two.

They should. Winter static electronics assembly problems don’t start at the bench mat or the ionizer. Plenty of them start with skin.

How much worse does static get in winter?

A lot worse. According to the ESD Association, a person walking across a carpet can generate about 1,500 volts at 65% to 90% relative humidity. Drop the air to 10% to 25% and the same walk can build up to 35,000 volts.

You won’t feel a discharge until somewhere around 3,000 volts. But a sensitive component can be damaged by a few hundred volts or less, which means most of the damage on a dry day is damage nobody felt. It shows up later as a latent failure, or as a board that passes test and comes back from the field.

Why do dry hands matter to a wrist strap?

A wrist strap only works if it makes good contact with skin. The strap gives the charge on your body a path to ground, and that path starts at the back of your wrist.

Dry, flaking skin is a poorer contact than healthy, hydrated skin. So the same strap, on the same person, can do a worse job in January than it did in July. Most of us check that the strap is on. Fewer of us think about what it’s sitting on.

And the people on your line wash their hands, glove up and degown more in a shift than almost anyone else in the building. That cycle strips skin fast. Winter air finishes the job.

So why not hand out whatever lotion is in the break room?

Because the wrong lotion is its own contamination problem. Most retail lotions are built on mineral oil, silicones or fragrance oils. They leave a film on the hands, and anything on the hands ends up on the board.

One bad solder joint can fail an entire assembly. A film or residue that interferes with solderability is not a small thing to a quality department. That’s why most ESD-controlled areas ban outside lotions altogether, and that’s the right call.

The answer isn’t no lotion. It’s the right lotion, approved and stocked at the line, so nobody has to choose between their hands and the product.

What to look for in a lotion for an ESD area

• Non-contaminating. Water based, with no silicones, no lanolin and no mineral oil. Nothing that leaves a film on the hands or a residue that affects solderability.
• ESD safe. It should support your ESD control program, not work against the wrist strap.
• Glove compatible. It shouldn’t degrade the gloves your people wear over it.
• Fast absorbing. If it sits on the skin, it ends up on the work.

Why we built ours for this exact problem

R&R made its first blue lotion in 1983 for a circuit-board plant, and electronics is still the market we’ve served longest. I.C. Lotion (the blue one) is DI-water based, with no silicones, no lanolin and no mineral oil, so it leaves no film or residue that would hurt solderability. It carries NSF E4 registration and won’t degrade the gloves your people wear over it.

It supports an ESD control program. It doesn’t replace one. A lotion is not a grounding device, and it’s no substitute for testing wrist straps at the start of every shift.

For the bench itself, our I.C. Topical Antistat treats surfaces that keep building charge in dry air. In testing it dissipated a static charge in 0.07 seconds at 12% relative humidity, well inside the 2.0-second limit.

What to do this week

1. Check your building’s humidity. If it’s under 30%, you’re in static season whether the calendar says so or not.
2. Test every wrist strap at the start of the shift, and log it.
3. Walk the line and look at hands. Cracked knuckles are a quality issue, not just a comfort one.
4. Put an approved, non-contaminating lotion at the line so nobody brings one from home.

If you’d like samples of I.C. Lotion or Topical Antistat for your line, ask your distributor or request a sample here. We’ll also run a free 20-minute session on winter ESD control for your team, in person or by video.

Your gloves are on, and your strap is on. Make sure the hands under them are ready for winter.