ESD question
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Hi all,
How do you correctly use an ESD wrist strap when building a K2? Can I directly plug it into the ground terminal of a regular socket (it appears to be made to fit) or can I connect it to the chassis to ensure no potential exists? The only time I've used a strap was a case where I had a specific grounding bus to connect it to. Thanks! -- "Do the right thing. It will gratify some people and astonish the rest." ~Mark Twain _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Kirk,
While the latter may offer more protection than nothing at all, I have been trained to use the former method. Grounding the ESD mat and wrist strap to a true earth ground will properly "siphon" off any residual static charge. The wrist strap should measure approximately 1 Megaohm to ground as there is an integral resistance in the cord which will prevent you from becoming a human fuse in the event of a dangerous/lethal voltage coming into contact with the mat. I expect there will be others who will weigh in on this, but I can tell you my training came from well over 25 years in field service, 16 of which were with Hewlett-Packard. At H.P. I had to be recertified every year in ESD prevention techniques, not to mention a slew of other things (like electrical safety). H.P. didn't mess around. Best of luck. Vin KR2F K1-4 s/n:1977 KX1 s/n:1476 (under construction) ----- Original Message ----- From: "Kirk Brown" <[hidden email]> To: <[hidden email]> Sent: Saturday, July 22, 2006 10:14 AM Subject: [Elecraft] ESD question > Hi all, > > How do you correctly use an ESD wrist strap when building a K2? Can I > directly plug it into the ground terminal of a regular socket (it > appears to be made to fit) or can I connect it to the chassis to > ensure no potential exists? The only time I've used a strap was a case > where I had a specific grounding bus to connect it to. > > Thanks! > -- > "Do the right thing. It will gratify some people and astonish the > rest." ~Mark Twain > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Kirk Brown-2
Kirk
I use a low cost earth mat and wrist strap. In order to connect them together (and to earth) I have an aluminium bar alongside the work bench, this in turn connects via a length of "hook up" wire and crocodile clip to the station ground. At the start of each session I check there is continuity between the mains earth and the bar using a multimeter. Obviously, some crocodile clips are better than others... 4mm plugs are fitted to the mat and strap, so if yours have these you may consider making a small box with matching sockets and then a flying earth lead to a station ground. You didn't mention an earth mat, these are very handy but I would avoid the field service types with the component and lead "pockets" as the flat rubber bench mats are generally nicer to use on a bench. Some mats can be very expensive, I use the Maplin (UK electronic supplier) part number YJ90X mat, however Maplin seem to have "discontinued" all their mats and only stock wrist straps! Maybe standards are slipping, or folks just don't understand the need for mats as well as straps. 73 Dave, G4AON K1 #1154 K2 #1892 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hello Dave and all,
I have and old mat with a wrist strap attachment, meant to be used with a keyboard. I don't like wrist straps, so I use a piece of 1" square pcb board and tuck it next to my skin, under my belt. This frees up my hand. This square of pcb board is grounded through it's coily cord which snaps on to the mat. The mat doesn't have any other point of connection, so I soldered a piece of wire to the bottom of the snap connector, and this is connected to ground. I use a wooden workbench and don't actually use the mat at all, when working on electronics - just the pcb board tucked under my belt. Do I really need the mat, and should my vise be sitting on the mat? Thanks, 73, Paul -ve1dy- > mats and only stock wrist straps! Maybe standards are slipping, or folks > just don't understand the need for mats as well as straps. > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I make sure the grounds for all the equipment on my bench are tied together.
That also means that they are tied to the mains ground, since the 'scope, soldering station, bench power supply and a few other items are all plugged into mains outlets. My wrist strap connects to the same ground, through its 1 meg resistor of course, as is my static-dissipating mat. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Ron D'Eau Claire wrote:
> I make sure the grounds for all the equipment on my bench are tied together. > That also means that they are tied to the mains ground, since the 'scope, > soldering station, bench power supply and a few other items are all plugged > into mains outlets. > > My wrist strap connects to the same ground, through its 1 meg resistor of > course, as is my static-dissipating mat. I also have an aluminum yardstick (meterstick) attached to the front top of my bench and connected to ground through a 1M resistor. Even if I forget to put on the wrist strap, my hands often rest on this -- and it's useful for measuring lengths of wire for toroids, too. In addition, the metal muffin tin I use for holding small parts has a ground lead and 1M resistor of its own. I have a clip lead with resistor that I can clip to my Panavise (used for holding circuit boards) or anything else, like a chassis. Finally, I removed the carpet from my shack and replaced it with light colored vinyl tile. This produces less static as well as making it easier to find dropped parts and clean up cat messes (now we are getting to the more-than-you-wanted-to-know part). Today the relative humidity in my room is 39% -- very dangerous for ESD. The temperature outside is expected to reach 113 f (45 c)! -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Kirk Brown-2
Paul VE1DY wrote "Do I really need the mat"
It's your personal choice, however when I worked in the electronics industry we had wooden benches with anti-static mats on them. I admit the static risk is low, the cost of damage to a part in something as complex and expensive as a K2, doesn't seem worth even a low risk. We were always told that static damage isn't always immediately obvious and that parts may be been stressed and suffer from premature failure at a future date. 73 Dave, G4AON _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Dave wrote:
> ...We > were always told that static damage isn't always immediately obvious and > that parts may be been stressed and suffer from premature failure at a > future date. > > 73 Dave, G4AON As an example, a coworker and I were doing final testing of a prototype board we had just finished. He came back into the lab, forgot to ground himself on a dry January day, and pointed at a chip on the board while talking - and of course it was the expensive $500 chip. We both heard and saw the little lightning bolt between his finger & the IC! Everything seemed fine after extensive, careful testing & we were relieved. But a couple months after the board was fielded for testing strange errors kept occurring, and after much frustrating debugging we learned that the zapped chip was the culprit. Going through that once was more than enough. So I was very glad to build my K2 on an anti-static mat with grounded wrist strap! Mike ab3ap _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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That's a great ESD story Mike. I can almost hear the groans that must have
erupted when that little spark hopped over to the I.C. Even being installed on the board couldn't save that one. Mats and straps are wonderful, and should be as much a part of any workbench as a soldering iron and good lighting. But it doesn't always have to be exotic mats and straps. If that fellow had simply touched a ground before poking at the board, there would have been no spark and no damage. I've done a lot of work servicing electronics in the "field", far from bench resources. All it takes to be as safe as sitting at the bench with a wrist strap on is to touch a ground *before* touching anything else, and keep touching that ground again and again before touching other things. It needs to be an unpainted metal ground. An equipment case connected to the mains safety ground is FB. An earth ground is too. Consciously practice until it becomes second nature to touch a ground first, just we learned to pick up the soldering iron by the handle without thinking about it <G>. Several folks mentioned having a metal strip on their bench that they can touch before touching parts. That works beautifully, provided one remembers to touch it! My wrist strap has a clip where the ground wire attaches so it can be quickly removed when getting up. I quit using the clip to remove the ground wire after I found myself working at the bench wearing the wrist strap and realized that I hadn't reattached the ground wire. So I take the whole thing off now. It's obvious when I don't have it on. The best safety systems in the world are useless unless we develop the habits that ensure we use them! Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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> I've done a lot of work servicing electronics in the "field", far from bench
> resources. All it takes to be as safe as sitting at the bench with a wrist > strap on is to touch a ground *before* touching anything else, and keep > touching that ground again and again before touching other things... Another trick is to touch the person's hand before you touch the part they are handing you, then touch ground before you touch your work surface or assembly to re-establish ground. 73, Lyle KK7P _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Ron D'Eau Claire-2
On Monday 24 July 2006 13:35, Ron D'Eau Claire wrote:
> All it takes to be as safe as sitting at the bench with a wrist > strap on is to touch a ground *before* touching anything else, and keep > touching that ground again and again before touching other things. That is how I built my K2 and numerous CMOS and HCMOS projects. I have been using my 15 Watt Antex soldering iron since 1970 and continue to use it in the USA using a voltage doubling and mains isolating (not an autotransformer) transformer. I feel that my projects and I are safe. Ian, G4ICV, AB2GR, K2 #4962 -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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