ESD in Winter
Our Circuit Boards are in Danger in the Winter!
Okay, technically circuit boards are in danger all the time, but more so in the winter. Why? Because it’s easier to shock them. And when circuit boards get shocked, they can fail immediately or start doing crazy, bad things. There are two main culprits when it comes to electrostatic discharge (ESD) damage and the first is: you. Yes, you and your habits when handling circuit boards. The second is mother nature and her affinity for changing seasons. But first, the basics:
(Remember, this is simplified to retain your attention.) Electrostatic discharge (ESD) happens when two electrically charged objects have a sudden flow of electricity between them. You can rub almost any two objects together and one will get positively charged and the other negatively, for example: the simple act of unwinding tape, and some objects hold charges longer and stronger than others. This is where YOU come in- by utilizing best practices, you can minimize the risk you pose to your boards. On the flip side, your new knowledge will allow you to maximize the shocks you bestow on your loved ones. For instance, you (a being who holds a lot of positive charge) could wear a polyester shirt (a material that likes to hold negative charges) and shuffle across the carpet in your socks to the unsuspecting human on the couch…ZAP!
Where does mother nature come in? Well, she likes to decrease the humidity in the winter, and decreased relative humidity lengthens the amount of time an object will hold a charge. Simplified, moisture in the air or on surfaces acts like a film through which charges can dissipate. Are you a numbers person? Okay, here’re a few examples:
Walking on carpet: 35,000 volts at 15% RH versus 1,500 volts at 65% RH
Walking on vinyl tile: 12,000 volts at 15% RH versus 250 volts at 65% RH
So, now you’re convinced ESD is a problem in winter...but what can you do about it!? Make it super humid! Just kidding, don’t do that unless you want to deal with corrosion and other side effects. You can shoot for some middle ground, like 40%, with an air humidifier, but you’ll want to take other steps, too. The following are anti-static devices and when combined are quite effective at drastically reducing the threat of ESD:
Wrist straps: these are connected to metal clamps that connect to the desk or table to ground you
Heel grounders: these are designed to effectively connect with a grounded floor
Anti-static matting: for floors or tables, these have high electrical resistance
Ground cords: often connect to mats and best for non-mobile environments
- Anything labeled “antistatic”, such as lotion, tape, shoes, garments, etc.