ESD Question!
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Good afternoon All.
They say an un-asked question is the only "dumb" question. Well, here goes!
I'm an appliance operator and my technical skills are kinda shallow. I do have a DMM and know how to use it.
I'm in the planning stage of building my dream transceiver: aka an Elecraft K3.
After reading through the assembly manual [thanks to its availability on the Internet], it's very clear that I should not try such a project without an ESD Wrist Strap and ESD Mat. I have these in my possession as we speak. They were purchased from a commercial company advertising them as ESD items.
That leads me to my question. How can I be assured that this Mat IS grounding a PCB [or anything else] during the "build" process?
I checked the resistance of the Wrist Strap and sure enough there is a 1M Ohm resistor in there.
I cannot figure a way to check the Mat's grounding. It's "alligator clip" is attached to my station's woven metal Ground Strap system.
Any help would be appreciated.
Thanks and Best 73.
Jim.........
WA4NTM
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Jim,
There are *no* dumb questions! In fact, this is a good question and not asked nearly as often as it maybe should! The biggest issue with ESD is keeping a discharge from going *through* you equipment. In *theory*, an ungrounded system offers some protection from this, but it is not recommended. If you have any ground (third wire or station ground), that will suffice. Usually, the third wire ground is used. I believe that's because 1) its ubiquitous and 2) because its ubiquitous, it'll be at the same potential with most of the things you have in your house which intern means you'll have little chance of becoming a "bridge" circuit in a "ground loop" (two grounds with different potentials). While this usually isn't an issue, I have heard of ground loops with potentially hazardous voltages. Maybe not so much for people as for equipment. You should be able to check your mat the same way you checked your wrist strap. Measure between the alligator clip and the mat itself. You should get similar (~1 megohm) results. Its been a long time since I've messed with mine, but IIRC, you should be able to make this measurement. Now, whether the ground you've chosen is effective is another matter. An interesting "revelation" is to measure between your station ground and your electrical ground. And, as I understand it, your station ground should be bonded to your electrical ground at the panel's ground rod. Why? Well, it helps keep lightening from using your ground (and consequently, you equipment!) instead of the "designated driver," so-to-speak. Of course, any direct hit and all bets are off. In fact, because of EMP, you can have electronics that are not even plugged in get fried. Isn't that special! {'-) I hope this helps. Regards, kurtt Kurt Pawlikowski, AKA WB9FMC The Pinrod Corporation [hidden email] (773) 284-9500 http://pinrod.com [hidden email] wrote: > Good afternoon All. > > They say an un-asked question is the only "dumb" question. Well, here > goes! > > I'm an appliance operator and my technical skills are kinda shallow. > I do have a DMM and know how to use it. > > I'm in the planning stage of building my dream transceiver: aka an > Elecraft K3. > > After reading through the assembly manual [thanks to its availability > on the Internet], it's very clear that I should not try such a > project without an ESD Wrist Strap and ESD Mat. I have these in my > possession as we speak. They were purchased from a commercial company > advertising them as ESD items. > > That leads me to my question. How can I be assured that this Mat IS > grounding a PCB [or anything else] during the "build" process? > > I checked the resistance of the Wrist Strap and sure enough there is a > 1M Ohm resistor in there. > > I cannot figure a way to check the Mat's grounding. It's "alligator > clip" is attached to my station's woven metal Ground Strap system. > > Any help would be appreciated. > > Thanks and Best 73. > > Jim......... > WA4NTM > > ------------------------------------------------------------------------ > > _______________________________________________ > 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 capobs
Hi Jim, Unfortunately, you probably can’t
check to make sure the mat is actually an ESD mat, since it’s resistance
will be too high for your DMM to measure. It will just show as an open circuit
on a DMM. There are ways to measure the resistance
by letting the sheet discharge a capacitor and measuring the discharge rate,
but I’m guessing you wouldn’t be interested in doing that,
especially since getting reliable measurements is a bit tricky. That said, I wouldn’t worry about harming
your K3, so long as you wear your wrist strap. If your mat was advertised as an
ESD mat, it most likely is just that. And even if it is not, you should be
fine. if you ground your wrist strap and ground the chassis of the K3 while you’re
assembling it. 73, Jim W8ZR From:
[hidden email] [mailto:[hidden email]] On Behalf Of [hidden email] Good afternoon All. They say an un-asked question is the only "dumb"
question. Well, here goes! I'm an appliance operator and my technical skills are kinda
shallow. I do have a DMM and know how to use it. I'm in the planning stage of building my dream transceiver: aka an
Elecraft K3. After reading through the assembly manual [thanks to its availability
on the Internet], it's very clear that I should not try such a project
without an ESD Wrist Strap and ESD Mat. I have these in my
possession as we speak. They were purchased from a commercial company
advertising them as ESD items. That leads me to my question. How can I be assured that
this Mat IS grounding a PCB [or anything else] during the
"build" process? I checked the resistance of the Wrist Strap and sure enough there is a
1M Ohm resistor in there. I cannot figure a way to check the Mat's grounding. It's
"alligator clip" is attached to my station's woven metal Ground
Strap system. Any help would be appreciated. Thanks and Best 73. Jim......... WA4NTM _______________________________________________ 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 Kurt Pawlikowski
On the theory that an ounce of prevention is worth a pound of cure, I
try to minimize the static generation in the first place. Long before I had an anti-static mat I practiced static minimization. For example: 1) Don't wear insulated sole shoes when working on your equipment. And avoid nylon, wool, or other material in your clothing that might encourage static generation if it is accidentally rubbed (i.e., you shift your weight while seated). 2) If your work area floor is carpeted, spray Downy or some other fabric softener, diluted, using a spray bottle (like an old Windex sprayer) and lightly spray the area under your workbench and where your chair will be. Fabric softener is conductive and will help bleed away carpet static under reasonable conditions for a few hours. 3) Sit quietly in your chair while working, with your feet on the floor (no rubber soles). Don't shuffle your feet - especially if a carpeted area - and don't wiggle in your chair. 4) I have no pets, but many people have static-generators (aka cats) that wander freely through their work area. Induce the cat to not be anywhere near you when you are working, and in such a way that does not require you to move in your chair to keep it away from you. 5) Touch the frame of the equipment, then touch the ground area of the PC board, then assemble. This will equalize any charge differential between them. 6) If you are being handed a PC board, or handing it to someone, *first* touch their hand, *then* place the PC board in their hand. This will equalize the charge differential between your bodies. 7) Don't even think about using a plastic-based table as your K3 assembly area! I have some excellent 4' and 6' folding tables from Costco, but I don't use them for work areas. If I do have to use one for parts sorting or some similar activity, I use the static mat even if there is high relative humidity in the workspace! 8) Dry air is your enemy. Cold weather outside and forced-air heat inside are a recipe for static. If you don't have a humidifier, all is not lost, but you must be especially aware of static avoidance! Enjoy! 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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Wow, Lyle. You sound like the nuns in parochial school. But Sister, I
*can't* sit still! 73--Nick, WA5BDU (squirming and fidgeting) Lyle Johnson wrote: > > 3) Sit quietly in your chair while working, with your feet on the > floor (no rubber soles). Don't shuffle your feet - especially if a > carpeted area - and don't wiggle in your chair. > > > 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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Another thing that many people do not recognise with the need for ESD
protection is that the damage is not necessarily going to appear straight away. I'd like a dollar for every time somebody told me that they have never taken any precautions and everything works fine, not realising that they have maybe wiped years off the component reliability. Every time your body zaps something it doesn't necessarily blow but it sure does weaken things, maybe just a fraction but when stressed in service that will all factor in to the ultimate life and failure of the component. Martin, HS0ZED Ron D'Eau Claire wrote: > Those things are fine to do, **if** you are grounded or touch a ground before resuming work touching the parts. > > Simple movement of the arms while working can be dangerous as the fabric on your clothing rubs while you move. > > Remember, we're talking about ESD damage resulting from a *few volts* of static charge, not hundreds of volts or the kilovolts it takes to produce a little spark. > > Ron AC7AC > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Nick-WA5BDU > Sent: Thursday, December 18, 2008 5:01 PM > To: [hidden email] > Subject: Re: [Elecraft] ESD Question! > > Wow, Lyle. You sound like the nuns in parochial school. But Sister, I > *can't* sit still! > > 73--Nick, WA5BDU > (squirming and fidgeting) > > Lyle Johnson wrote: > >> 3) Sit quietly in your chair while working, with your feet on the >> floor (no rubber soles). Don't shuffle your feet - especially if a >> carpeted area - and don't wiggle in your chair. >> >> >> 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 > > _______________________________________________ > 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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