Thought others might be interested in this.

Picture attached of my low-bucks ESD work surface.

Built my first one about 25 years ago and a second one recently for my winter QTH.

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Materials Needed:

24 x 24 x 1/2 inch Smooth Sanded Birch Plywood --> (Lowes - about $18.18 today)

1/2 x 3/4 x 1/6 inch aluminum angle strip - 4 feet --> (Home Depot - about $9.27 today)

#8 Flat Head Sheetmetal Screws -- I like stainless steel

ESD Wrist Strap (got to be lots avail from Amazon - choose one and use it! )

Simple, you wire-on replacement AC plug with screw terminals inside. remove the Hot and Neutral prongs

1M ohm resistor.

1/2 round bead edging on the bottom front edge and/or top edge for appearances if you'd like.?

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Misc:

wire, ring connectors, alligator clip for wrist strap if it doesn't have one already,?

Heavy Duty Extra Wide Aluminum Foil, Scotch Tape,?

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The aluminum angle is screwed down on the top two sides of the Birch board.

Four evenly spaced screws per side. LIGHTLY countersink the holes for the flat head screws so they fit more flush.

That aluminum strip is only 1/6th inch thick.?

The board is just enough undersized in thickness that the 1/2 inch side of the angle just covers the edge without sticking past the bottom.

The aluminum foil is taped to the top of aluminum rails with plain old Scotch Tape. Clear the tape a bit from around the top left and middle screws on the left side.

Then use a ring connector and some wire to tie in the 1M ohm resistor to 'ground'.? And leave one of the middle left screws noted above a bit above the surface of the rail, clip in the wrist strap and gently snug down the screw.

Check continuity and verify the resistance to ground at several points on the foil and from the metal dot that connects to the inside of your wrist on the ESD strap.? Get in the habit of using the strap when ever you are handling potentially (or known!) ESD sensitive components.

In addition, just in case, I've gotten into the habit of touching the foil surface with both hands after sitting down to work, just in case a BIG spark in waiting has been building up :)

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After a few work sessions, just peel and replace the foil for a fresh looking surface.

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GREG KI4NVX

Nice idea, Greg.

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I prefer working on a non-conductive work surface, so I don't accidentally short things while testing.

There are several low-cost (under $30) ESD mats available on Amazon, including the wrist-strap, such as this $23 one:

Stan

I don't actually use that worktable for actual power on testing. At most, I ohm out detailed checkpoints or other ohmic confirmations of connections. If I've removed the board from the holder to do those sorts of checks, I place it on top of another non conductive surface ( manilla folders are my friend for lots of tasks).?

Any power on testing I do at my shack operating tables.

You are correct. The mats are nice.?

Just an old habit of mine from way back in the day before there were such things outside of pricey commercial sources. I think I picked it up on list of hints and kinks documents that Elecraft had in its website back when it was all kits and I built out a K2.?

GREG

A good ESD work surface is conductive, but not too conductive. ?That way it maintains equipotential between your work, your wrist strap, and your iron, but any inadvertent discharge that does occur is dissipated slowly and safely. ?I like these cheap conductive cardboard mats from Desco--they're intended to be disposable for industrial use, but last forever at home and take soldering heat well. ?The one in the photo was about $10 from Newark here in the US.

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Scott

I regard that as a potential deathtrap.

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ESD mats are cheap and far safer and will not ground you?

if you playing with line voltages or higher (tube gear).

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Also it has great potential to create a short on the

back or front of most circuit boards.

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--

Allison
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Post online only,?
direct email will go to a bit bucket.

On Tue, Feb 25, 2025 at 05:17 AM, spaine wrote:

A good ESD work surface is conductive

The correct word here would be "dissipative" - something that quickly dissipates static charge, but has a very high resistance to normal electrical currents.??

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As Allison said, inexpensive ESD mats are safer, and they are easy to get and use.? And even the $20 ones on Amazon, complete with wrist strap, will last a very long time.? I encourage all assemblers of qrp-labs kits to get one and use it.

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Stan KC7XE?

Are those cheap blue silicone soldering mats that are advertised as ESD protection really effective at protecting from ESD or are they just heat resistant??

On Tue, Feb 25, 2025 at 08:42 AM, Don VE3IDS wrote:

Are those cheap blue silicone soldering mats that are advertised as ESD protection really effective at protecting from ESD or are they just heat resistant??

While I don't have the means to test it properly, the one I have linked above has the following description:

On Tue, Feb 25, 2025 at 11:42 AM, Don VE3IDS wrote:

Are those cheap blue silicone soldering mats that are advertised as ESD protection really effective at protecting from ESD or are they just heat resistant??

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Good mats will have a snap or banana jack connection for grounding; either the mat or the grounding means will include a 1Meg resistor in series.

Without a ground where will the charge go?

73, Don N2VGU

I have the lovely task of testing all my company's esd surfaces and continuous static monitoring devices.??

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A couple of things I read here need to be said.?

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1. paper (Manila folders included)? is a static generating material.? It will create a static charge just lifting it off of cirtain material.? keep it 12"+ away from any static sensitive device.?

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2. the 1mohm resistor Don Brant mentioned is important for the purpose of allowing static charge to go to ground somewhat slowly in order to not make a spark.

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If you're work surface is properly grounded and you are not wearing a wrist strap with 1mohm resistor embedded,? then your charge will travel on the work surface to ground and may effect anything lying on the that surface.? we even have to remove all static devices from the surface before doing a surface test for this reason. Profe of receipt...I had a lightning strike that went across my metal desk and blew avhf/uhf radio up that was not even connected. Okay, maybe lightning is overkill example of static discharge but the principle is the same.?

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I'll shut up now.??

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regards,
Bryan, N0LUF

Not at all convinced by this . .? ??

I use an antistatic mat as my bench covering at all times, grounded, linked to PSU, linked to soldering iron.? ?It runs to the front of the bench so my arms rest on it automatically but for known super-sensitive work I wear a strap too.? ?

They wear out in time but the next is already in the cupboard.? ?ps their surface resistance is very high but a good GigOhm meter or tester will see it over a few inches and a HV insulation tester easily for a periodic test.? Their aim is to drain static slowly, do no harm to live circuits parked on them and also be non skid . .?

In a high value manufacturing environment, you do everything you can to avoid static damage.

Even rarely occuring failures can cost big money, perhaps even the loss of a large sale.

I think most hobbyists are a bit more relaxed than that.

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I'd bet an honest survey of Q*X kit builders would find that less than half have a static mat.

Most of the parts we use are either not inherently sensitive to static or they have protection

devices at each IO pin.? Protection is typically a Schottky diode from pin to ground and another?

from pin to Vdd, these discharge any hit that exceeds normal signal voltages.

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I guess the most sensitive part that we regularly work with would be the gate of the BS170's.

Be especially careful with static control when replacing those.? Once parts are soldered down

to the board, they are usually connected to other stuff that helps discharge a static hit.

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When I approach sensitive gear, I first touch a ground point to bring the device to the same potential?

as my body.? If static is in the air, I continue touching that equipment ground while working on it

as much as I can. Static sensitive parts such as the BS170's should be kept in the anti-static?

bag till you are ready to solder them into place.? If you first touch the bag (perhaps to open it)

before touching the sensitive part, no damage will occur. Then with the other hand I'd touch

the equipment ground before bringing the part to the equipment.? If you follow procedures?

such as this, most hobbyists should not have trouble with static damage.??

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My workbench does have a static mat, but I am not always at my workbench.

When at my bench, I generally don't strap in with a wrist strap, but instead lay an arm across

the static mat to establish a connection.??

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Now retired, but at work in an engineering environment, we generally followed procedures

like those above without getting yelled at.? It was generally our own design, and if something

were to fail we were well qualified to fix it.? I can't think of a single case where I felt I had

caused static damage over several decades of work.? Procedures in manufacturing

were somewhat more strict.

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When designing a board I often add a series resistor of perhaps 100 ohms to each sensitive

IO pin that goes out to a customer accessable connector if that won't compromise the intended

purpose.? The combination of the series resistor plus the protection diodes makes it pretty much?

bullet proof, unless they plug that wire into a wall socket.

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Jerry, KE7ER

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On Tue, Feb 25, 2025 at 05:43 PM, Bryan Curl wrote:

the 1mohm resistor Don Brant mentioned is important for the purpose of allowing static charge to go to ground somewhat slowly in order to not make a spark.

It is also a personal safety item, in series with the wrist strap it limits your current to ground in the event you contact a hot wire; it is best not to have a grounded conductor around your wrist when working with electricity.

73, Don N2VGU

On Tue, Feb 25, 2025 at 11:24 AM, Stan Dye wrote:

On Tue, Feb 25, 2025 at 05:17 AM, spaine wrote:

A good ESD work surface is conductive

The correct word here would be "dissipative" - something that quickly dissipates static charge, but has a very high resistance to normal electrical currents.??

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As Allison said, inexpensive ESD mats are safer, and they are easy to get and use.? And even the $20 ones on Amazon, complete with wrist strap, will last a very long time.? I encourage all assemblers of qrp-labs kits to get one and use it.

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My two cents, assembling a QRP labs kit doesn’t require ESD protection. It doesn’t hurt, but there isn’t any major ESD risk.?

On Tue, Feb 25, 2025 at 06:16 PM, Corey KC9RAV wrote:

assembling a QRP labs kit doesn’t require ESD protection. It doesn’t hurt, but there isn’t any major ESD risk.?

And that is why some people have failures in their assembly, or after operating for a time (due to a weakened part).

There is indeed ESD risk.

Yes, the ESD risk is minimized since most of the parts have ESD protection on their input pins, and are pre-assembled onto the CCA.?

And the risk is not as critical (like Jerry mentioned) since we are hobbyists, not making mission critical gear - and we can easily fix it if it breaks.

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But the highly integrated parts in the Q*X with fine internal lithograpy (all of the ICs except the 3.3V regulator) can indeed be damaged with careless handling.?? ESD may not cause failure immediately, but may weaken a part that may then fail later.? Yes, even with the ESD protection on their pins - it just takes a larger ESD event.? The pins are typically ESD protected to 2000V, which protects well if handled carefully.? But picking up a styrofoam coffee cup from your work table and brushing it against the cuff of your shirt can generate well over 20,000 volts of static on your hands - then touching one of those devices without discharging yourself will indeed damage it.? Thankfully most of us don't use styrofoam on or near our work surfaces, but many other materials, including carpeting, the covering on your chair, your chair's roller wheels, and even your clothing can readily generate high static charges, unless these materials are of the anti-static variety.? And how many of us have checked??

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Sorry for the tirade, but I had to take ESD refresher training every 6 mo during much of my career.? And it was interesting to learn of the common materials and simple body movements that can generate static tens of times greater than the typical 2000V ESD protected device can withstand.? So unless you know you are safe, use an ESD mat and ground yourself after moving or wear a wrist strap.? Assembly areas where I worked have chairs and floors that are known not to generate static.? And we still had to wear our wrist bands or shoe straps, and work on ESD mats that were tested and qualified every 3 mo.? Yes we worked on mission critical devices, and we had to avoid all ESD risk, unlike hobbyists.?

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After the item is assembled, the risk is lower, because there are many paths to dissipate ESD, and you usually don't directly touch an ESD sensitive device without previously discharging the ESD through a benign path.? And maybe that's why we don't often kill the ICs in qrp-labs kits.

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But please don't believe that there isn't any ESD risk unless you are specifically minimizing it in some way.

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Stan KC7XE

A post mentioned “1mohm resistor”. Is that 1 milliohm or 1 megaohm? I assume 1 milliohm because the “m” is not capitalized.

DK,

??? Whoever mentioned it meant 1 MEGohm.? The resistor serves 2 purposes: -Prevent high current from flowing between the circuit and ground (high current flow is what?destroys ICs), -Protect *YOU* from the flow of high currents should you inadvertently touch a high voltage while "grounded".

???? If that resistor was only a milliohm, it wouldn't be able to serve either purpose.

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Bill

W2EB

East Syracuse, NY

On 2/26/2025 at 2:24:31 PM, DK via groups.io <donaldphilbin@...> wrote: