ESD verification - Resistivity meters

[requim]

I would like to verify that my esd mat (wrist strap, etc) is all working properly.  How can I verify it's all working according to plan?  Do most people take it on faith that it works once they hook everything up or are you going through some verification process, and if so, how are you doing it and what equipment are you using?

At work we have a variety of ESD testers among them (our older gear) we have a 3M 740 wrist strap + shoe tester and I've seen guys using something along the lines of a 3M 701 Static Control Surfaces Test kit (Megohmmeter).  Should I considering purchasing these, or something like them, for my home lab? 

[nanofrog]

Not sure if many bother at home, but FWIW, there are used ESD workstation monitors on eBay cheap.

[katzohki]

No, don't bother with that stuff I'd say. Most of the shops I've been in take ESD protection to a little bit of an extreme (I get stuff like plastic bobbins, screws, and capacitors shipped to me labeled as static sensitive). Static mat and wrist strap is enough for the home user. I take the approach of knowing what's sensitive (CMOS tech) and using caution when I work with it. I'm not sure I would be really careful unless I was handling MOS transistors.

[requim]

My primary use case is with pcb's.  Primarily for computers - pci, pci-express, motherboards, etc. along with the occasional teardown of (mostly) broken electronics goods. 

Is your suggestion then that ESD protection / caution for these components isn't really necessary?  Or that verification itself is not necessary?

[katzohki]

Verification is not necessary. ESD protection - can't hurt.

Know what ground is and connect your wrist strap to that. Doesn't count if the box you're working on is unplugged, you have to connect to real ground. If you're working on a board level there is less risk. Do whatever makes you comfortable.

[nanofrog]

My primary use case is with pcb's.  Primarily for computers - pci, pci-express, motherboards, etc. along with the occasional teardown of (mostly) broken electronics goods. 

Is your suggestion then that ESD protection / caution for these components isn't really necessary?  Or that verification itself is not necessary?

Protection is definitely a good idea (mat + wrist strap).  And this is really as far as you'd need to go in a home lab environment. If you're on the paranoid side, a continuous ESD monitor can be had cheap (used on ebay), but no need to get more extensive than that (money could be put to better use elsewhere).

[requim]

The reason for my concern is that in the ~ 2 years I've worked at my current company (and spent a limited amount of time in the labs / esd environments ) I've gone through several sets of heel straps and a pair of esd shoes and the only way I knew they were bad was because the test equipment told me.   Visually none of them appeared to have any defects, so I would have never known, hence my concern for my home environment using wrist straps, etc. 

How do you guys know when your wrist straps / mats have failed without some sort of verification procedure / equipment?

[xwarp]

If you are moving your equipment around on a daily basis, there really shouldn't be an issue. Having looked at ebay, there are multiple lisings for ground monitors for pretty low prices. You should be familiar with those.

At home, I don't generally worry much about static because I generally don't carry the parts or uut around from my workbench.

In regards to heelstraps, I HATE them, so ESD shoes it is. So far, the best I've found are the Doc Martin's.

And a tip to anyone who may use them, I generally take a vacuum to the inside occasionaly and also, if they fail footware test, I spray anti-static treatment under the insole and then on the inside of the upper.

[nanofrog]

I use a metal wrist strap, and spot check with a DMM (my parts are all within reach with the strap still connected). Not as convenient as a continuous ESD monitor, but it's an acceptable compromise IMHO, so it's on the bottom of my priority list right now.
 
You could also consider the fabric softener trick that was mentioned in this thread (i.e. floor surface treatment).

FWIW, I use the following:
strap
cord
ground parking block

[sacherjj]

While most people seem quick to dismiss ESD, it all depends on the environment and type of equipment you are working on.  As gates continue to get thinner, ESD will become more sensitive.  In the Midwest US, we really only have half a year to worry about ESD.  90% humidity tends to solve the problem for us.

The biggest issue is the small discharges that you don't feel, but do damage to gate insulators that cause premature failure in months to years.  All this without knowing there was an issue.  We are working on a 5-10 year, high reliability lifespan device.  While sometimes it feels like being anal, when the cost of getting the product to its destination is multiple times the cost of the product, some precaution is not a bad idea.

All of our assembly stations will be using a monitor that has under and over ESD buzzers.  These are $50 or so from reputable US ESD dealers and probably working Chinese versions are $10-20 on ebay.  It just makes sure that you aren't very low resistance grounded (dangerous and non-ESD safe) or too high of resistance grounded (non-ESD and probably either no protection on or broken wire or no skin contact.)

I highly prefer the smock with wrist bands that has snaps on the pocket.  I can unplug and toss my lead into the pocket, then just plug in when I sit back down at my bench.  Gives more freedom at the hands.  I wouldn't do this without active monitoring, because there are possibilities of not grounding as well as a wrist strap.

[katzohki]

People dismiss ESD because a lot of devices have in-built ESD protection, assembled boards are at less risk, and a lot of the ESD protection equipment is really over-sold to managers who don't understand what it even is! Hey I've got an anti-bear rock you might need. How do you know it works? Well do you see any bears around?

Don't get me wrong, I'm all for ESD safety, just don't take it to an extreme when you don't need to.

Something I wanted to point out; your ESD shoes or heel straps are useless unless you have a flooring designed to use it. Won't do any good on carpet at home, but you can get an ESD floor mat. One place I was in spent tens of thousands of dollars on a special ESD coating floor and never bothered to have anyone wear the heel straps.