How antistatic or ESD safe mats work - Page 1
Forum section: electronics / beginners

author: lumdef
author_rank: Contributor
timestamp: March 18, 2025, 08:29:05 am
content: 1. Do the terms "antistatic", "esd", "esd safe", "static safe" mat refer to the same thing?2. The attached picture demonstrates the workings of one of the aforementioned. Which one is it?3. The picture shows how charged human hand/body is being discharged through the bottom conductive layer of the mat, which is clear. How, however, does it handle charged electronic component on the mat if the top layer has high resistance? If my body is neutral, but the component is charged, that would lead to ESD (i.e. zap).

author: golden_labels
author_rank: Super Contributor
timestamp: March 18, 2025, 08:57:19 am
content: Quote from: lumdef on March 18, 2025, 08:29:05 amIn general, terms “antistatic”, “ESD”, and “ESD safe” have very different meanings. But when combined with “mat,” it’s a shortcut to name the same thing. It means a mat, that safely equalizes charge the same way as a wristband does.(question #2 made obsolete by the reply above)Quote from: lumdef on March 18, 2025, 08:29:05 amSince it’s high resistance, it does conduct, doesn’t it? So this way the charge is dissipated. It works the same way as the ESD wristband, which has MΩ range resistor built-in.The high resistance guarantees the current is low, so there is no damage to the component. Unlike with “zaps,” where the current is high and can easily cause damage.

author: lumdef
author_rank: Contributor
timestamp: March 18, 2025, 11:16:17 am
content: Thank for the clear mat explanation. Regarding antistatic bags, how do they work? Where do they dissipate charge if they are not grounded like mats?

author: SteveThackery
author_rank: Super Contributor
timestamp: March 18, 2025, 01:33:45 pm
content: Quote from: lumdef on March 18, 2025, 11:16:17 amThey don't. They equalise the charge across the whole bag (and it's contents).

author: bte
author_rank: Regular Contributor
timestamp: March 18, 2025, 11:46:17 pm
content: Quote from: lumdef on March 18, 2025, 11:16:17 amThis is an interesting video about ESD bags:https://youtu.be/BUW6h88weXU

author: ArchieAltz
author_rank: Contributor
timestamp: March 18, 2025, 11:53:06 pm
content: As for the first question , yes antistatic/esd/static safe are the same.As for the second one, the first layer is the discipative one and it has a high resistance so it removes any risk of damaging your components cause of the low current.

author: golden_labels
author_rank: Super Contributor
timestamp: March 19, 2025, 06:03:02 am
content: Quote from: lumdef on March 18, 2025, 11:16:17 amLet’s start with there being different kinds of “ESD bags.” Unlike with mats, where it’s just an imprecise shortcut to name the same thing, with bags there is distinction.There areanti-staticbags. They prevent charge from being generated from contents being in contact with the bag. Hence they avoid the initial problem. However, they can’t deal with charge generated from other sources.There aredissipativebags. They equalize charge present on the contents. Not against any external reference. Those have basically the same property and purpose as ESD mats and wristbands, except not grounded.While not strictly ESD, but often called that, there are alsometalized/shieldedbags. Their purpose is to act as aFaraday cage. They stop external currents and electromagnetic radiation from penetrating the contents.Any decent seller and manufacturer will deliver a datasheet or a proper description, that tells which one it is and what are the parameters. However, if you buy just generic “antistatic bags” off Ebay, it is a lottery. You may guess by the color and look, but there really is no standard. Nothing prevents the seller from just sending you normal bags with pink pigment either. For this reason, if you need ESD protection, buy them in bulk from any major electronic components vendor. Even better: some send literally everything(1)packed in dissipative bags. So you may get some for free, if you only need a small number and don’t mind labels.⁂Now, coming back to the question of grounding. There doesn’t need to be grounding. ESD mats and wristbands use a ground connection for two reasons. Most charge build-up is against ground in the first place, so it’s natural we want to use it as a reference. And Earth happens to be huge(citation needed)and not having any significant imbalance of charge carriers, so it makes a good “tank” to receive any excess charge. Earth is also widely available on Earth, freely and in great abundance.But dissipation is just equalization of charges. Charge carriers don’t disappear.2They just flow between elements, until there is no difference between elements of the system. Earth doesn’t need to be involved. In dissipative bags that equalization happens between different points on the contents and also the bag itself. If you touch the inside of the bag, this entire system is also equalized with your body.(1)To the point that e.g. TME sends dissipative bags… in an even larger dissipative bag.(2)This is why any “wireless ESD wristbands” can’t work.

author: SteveThackery
author_rank: Super Contributor
timestamp: March 19, 2025, 10:27:24 am
content: @golden_labels: am I right in thinking that anti-static bags also provide a dissipative effect? I recall being taught this, but I could be wrong.Also, is it possible to distinguish visually between anti-static and dissipative bags?

author: golden_labels
author_rank: Super Contributor
timestamp: March 19, 2025, 10:05:18 pm
content: I’d say, that anti-static and dissipative are two separate features. Perhaps there are bags, that are both anti-static and dissipative. But I’m not sure, how would that work and if that makes any sense. Not an expert on the topic, but I don’t see much purpose in a bag being anti-static, if it’s already dissipative.As for the other question, it was answered to the post you replied to:Quote

author: golden_labels
author_rank: Super Contributor
timestamp: March 20, 2025, 05:17:26 am
content: @SteveThackery: after giving it a bit of thought, it may make sense to have both features. Purely dissipative materials may not protect against charges when putting things into or removing from a bag. But, as I said, I’m not an expert: you’d need to ask somebody with deeper knowledge in materials science or ESD safety.