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View Full Version : Laminating Copper Sheet to workbench?



superUnknown
12-23-2014, 01:59 PM
http://cdn.instructables.com/FJW/ON7Y/I3THF74E/FJWON7YI3THF74E.MEDIUM.jpg

Details here: http://www.instructables.com/id/Copper-Workbench/

I made a copper workbench for soldering and light duty work. But I didn't manage to get it laminated perfectly flat, so I burnished it so the distortion wouldn't drive me round the bend. That is, any further round the bend.

Any advice for getting it right the next time 'round?

P.S. I've seen the error of my ways and am using a small tile of ESD mat to do actual IC work. :o

Joe Rogers
12-23-2014, 02:30 PM
I know that when I solder, the drips I lose are easy to scrape off and remove. Not sure a copper work surface would promote that ability...
Pretty though.
Joe

topct
12-23-2014, 02:40 PM
No, okay two no's.

superUnknown
12-23-2014, 02:42 PM
I know that when I solder, the drips I lose are easy to scrape off and remove. Not sure a copper work surface would promote that ability...
Pretty though.
Joe

It does. Thermal mass of the copper sheet... the solder solidifies on contact and slides right off.

Paul Alciatore
12-23-2014, 03:44 PM
Boy, that must be one expensive work bench. You do know that they make conductive pads for electronic benches.

I will go you one better. I have worked in electronic repair and construction for all my career; 45 plus years. I have never worried about having a grounded, conductive bench top and have NEVER had any problems with static discharge. Most of my electronic benches were metal frames with wood or particle board tops. I did not deliberately touch the metal frames or take any other precautions, but the mere fact that they were close at hand was apparently enough to prevent any static problems. Oh, and the soldering irons were grounded so they also tended to prevent any static charge accumulation. Besides, most modern, static sensitive components have protection diodes built in to the pin connections. You would have to really try hard to damage them.

In my experience, it is a non-existent problem. Old wives tale. Myth used to sell static control products. Flin-flam!

I have an electronic bench next to the desk where I am typing this. It has no provision for static control. Oh, and the floor is a carpet. NO PROBLEMS.

On getting the copper to bond better to the table top, I would use laminate glue. AKA, contact glue. And roll it down from the center out. Use thin wood strips to separate the two and remove them one by one, in order, rolling the copper down after each is removed. Just like applying a plastic laminate.

mickeyf
12-23-2014, 03:45 PM
I've been wondering what I was going to do with that 20 sq. ft of pc board I've been hanging onto for years even though I don't etch boards any more...

KMoffett
12-23-2014, 04:06 PM
Yikes!!! A highly conductive metal top on an electronics workbench? That's just asking for trouble. I can't think of a more dangerous setup.

From the Indestructible:
"Strictly speaking, a conductive work surface isn't the best for electronics work." A potentially lethal understatement!
"...It does protect against static electricity..." Not true....just the opposite.
"...But it also provides a low impedance path to ground." Just what you don't want to safely discharge static.
"...One must take care not to drop any live conductors onto the worksurface or you will get an arc!" No s**t!

The synthetic mats that he didn't like, bleed off static charges through a high resistance that limits current to a safe level for the components...and you. They also have high resistance across the surface, so even if both leads of a power source touch the mat, it doesn't short it out.

Please do not do this!!!

Ken

superUnknown
12-23-2014, 04:18 PM
Yikes!!! A highly conductive metal top on an electronics workbench? That's just asking for trouble. I can't think of a more dangerous setup.

From the Indestructible:
"Strictly speaking, a conductive work surface isn't the best for electronics work." An a potentially lethal understatement!
"...It does protect against static electricity..." Not true....just the opposite.
"...But it also provides a low impedance path to ground." Just what you don't want to safely discharge static.
"...One must take care not to drop any live conductors onto the worksurface or you will get an arc!" No s**t!

The synthetic mats that he didn't like, bleed off static charges through a high resistance that limits current to a safe level for the components...and you. They also have high resistance across the surface, so even if both leads of a power source touch the mat, it doesn't short it out.

Please do not do this!!!

Ken

Ah mom, geeze, you're embarrassing me in front of my friends.

superUnknown
12-23-2014, 04:20 PM
Boy, that must be one expensive work bench. You do know that they make conductive pads for electronic benches.

I will go you one better. I have worked in electronic repair and construction for all my career; 45 plus years. I have never worried about having a grounded, conductive bench top and have NEVER had any problems with static discharge. Most of my electronic benches were metal frames with wood or particle board tops. I did not deliberately touch the metal frames or take any other precautions, but the mere fact that they were close at hand was apparently enough to prevent any static problems. Oh, and the soldering irons were grounded so they also tended to prevent any static charge accumulation. Besides, most modern, static sensitive components have protection diodes built in to the pin connections. You would have to really try hard to damage them.

In my experience, it is a non-existent problem. Old wives tale. Myth used to sell static control products. Flin-flam!

I have an electronic bench next to the desk where I am typing this. It has no provision for static control. Oh, and the floor is a carpet. NO PROBLEMS.

On getting the copper to bond better to the table top, I would use laminate glue. AKA, contact glue. And roll it down from the center out. Use thin wood strips to separate the two and remove them one by one, in order, rolling the copper down after each is removed. Just like applying a plastic laminate.

Haha Flim Flam, good to know Paul! Too late for me I'm afraid. Now I'm stuck with a nice looking copper worksurface instead of a flaky old particle board desk. Durn.

Gary Paine
12-23-2014, 04:28 PM
Any advice for getting it right the next time 'round?[/B]

P.S. I've seen the error of my ways and am using a small tile of ESD mat to do actual IC work. :o

I've used the laminate installation trick with contact cement of laying a roll of wooden dowels on the glued surface, carefully aligning the glued edge and pressing it along that edge. Remove the dowels one at a time as you flatten the surfaces together from that starting edge. Worked great, but there's no shifting it if the starting edge isn't right.
We protected our labs with ESD mats and ground straps for delicate circuit work. Static really used to build up when Styrofoam and plastic bags were used to package products. Shaking around in shipping crates, etc. We had to use ESD bags on some product. We once measured a charge held by an empty Styrofoam cup at 60,000 volts.

oxford
12-23-2014, 04:43 PM
For the original question, what was the process you used to laminate it the first time around? I think it may be hard to get it perfectly flat so a polished surface doesn't look wavy. I would do like Paul Alciatore suggested with contact cement. The key is going to be getting a consistent layer of it down, rolling it would be better than a brush. Spraying it may also be an option.

There may also be some "double sided tape" out there that would also work for you. Here is a McMaster link for what they offer, some of it is only a couple of thou thick. http://www.mcmaster.com/#fastening-tape-with-adhesive-on-both-sides/=v5ifb8

Doozer
12-23-2014, 04:43 PM
I've used the laminate installation trick with contact cement of laying a roll of wooden dowels on the glued surface, carefully aligning the glued edge and pressing it along that edge. Remove the dowels one at a time as you flatten the surfaces together from that starting edge.

^^^^^This!^^^^

--Doozer

mickeyf
12-23-2014, 05:05 PM
We once measured a charge held by an empty Styrofoam cup at 60,000 volts.

And when full of espresso it was twice that...

Baz
12-23-2014, 06:33 PM
Some people are static generators and some are not. So when PaulA says he has never had a problem that is just him and not true of the general public. It all depends on your clothes, your shoes, the furniture and above all YOU.
The bench should have a static mat that is earthed through a 1M ohm resistor. You do not want a direct line to earth. Pretty standard HSE and static requirement worldwide. Electronic mains equipment used on it should be run through an isolating transformer. The mat is special stuff that is sufficiently insulating that low voltage pcbs can be powered up on it without shorting yet static is discharged.

The copper plate idea is the equivalent of running a lathe wearing gloves, a kipper tie and a tassled jacket.

oxford
12-23-2014, 07:39 PM
The copper plate idea is the equivalent of running a lathe wearing gloves, a kipper tie and a tassled jacket.

Well, I may have a pair of leather gloves but I have no idea that a kipper tie is and wouldn't be caught dead in a tassled jacket.;)

J Tiers
12-23-2014, 08:34 PM
Copper sheet is the worst possible idea. Almost.... There is probably an idea worse.

Now, there is a really GOOD idea involved, there, but it takes some changes. I have a copper sheet at my workbench also. But it is UNDERNEATH, and insulated from me.

It's there to provide a local ground plane so that whatever I am working on is not hanging out in space away from all shielding. keeps the stray noise down when you have a PWA out for service and want to see something other than picked-up crap. I can, if I want, ground things to it, directly, or via a capacitance.

Plop a covering over that sheet, and put a real static mat down, Then you can ground the sheet and not have the hazards, so you ahve a nearby ground plane.



In my experience, it is a non-existent problem. Old wives tale. Myth used to sell static control products. Flin-flam!


Nonsense! NONSENSE!

Your experience is directly opposite to what I have repeatedly seen.

I had a boss who believed what you said. I bet him that I could destroy a 250W TO-3 transistor with static without hardly trying. I won that bet.

All I did was pick it up off the wood meeting room table, I held it by the emitter lead, got up and walked a couple steps over and touched the case to the wall switch screw. It then measured about an ohm resistance in any polarity or lead combination.

We had a product with a bipolar opamp near one edge. production said they had a very high failure rate, and demanded we change the type used. Investigation showed that the device wa right wher the assembler's thumb landed when putting the board in the chassis. Static control stopped the problem 100% in 5 minutes.

That latter was the experience every time a similar problem was noted... we finally convinced production to go whole hog on it, and both in-house failure rate as well as field reliability was documented to be better afterwards.

Sorry to pop the pretty bubble, Paul, but "the world knows better than what you wrote".

lakeside53
12-23-2014, 08:42 PM
It depends where you live. In Seattle - good luck destroying anything with static. In Montana and Illinois in the winter, I did that regularly. lol..

I hate conductive benches for working on. I use static dissipative laminate benches, but... they are only that way if you keep them CLEAN and spray with the correct cleaner regularly, which I don't.

Paul Alciatore
12-23-2014, 09:08 PM
I finish my "flaky old particle board" tops with about 3 to 5 coats of water based, polyurethane varnish. They look great and wear very well.



Haha Flim Flam, good to know Paul! Too late for me I'm afraid. Now I'm stuck with a nice looking copper worksurface instead of a flaky old particle board desk. Durn.

Paul Alciatore
12-23-2014, 09:14 PM
Well, I guess I have never been stupid enough to do that. I mean, really.

If you are going to do this, I would recommend one of the commercially sold static mats, which are high resistance and will not short things out or allow an instantaneous discharge which would do exactly what you are talking about with touching the light switch's grounded screw.

But again, with over 45 years of professional work in electronics, I have never had a static problem with a single device. NEVER! It can be done, but you have to try, AS YOU DEMONSTRATED!




Copper sheet is the worst possible idea. Almost.... There is probably an idea worse.

Now, there is a really GOOD idea involved, there, but it takes some changes. I have a copper sheet at my workbench also. But it is UNDERNEATH, and insulated from me.

It's there to provide a local ground plane so that whatever I am working on is not hanging out in space away from all shielding. keeps the stray noise down when you have a PWA out for service and want to see something other than picked-up crap. I can, if I want, ground things to it, directly, or via a capacitance.

Plop a covering over that sheet, and put a real static mat down, Then you can ground the sheet and not have the hazards, so you ahve a nearby ground plane.


Nonsense! NONSENSE!

Your experience is directly opposite to what I have repeatedly seen.

I had a boss who believed what you said. I bet him that I could destroy a 250W TO-3 transistor with static without hardly trying. I won that bet.

All I did was pick it up off the wood meeting room table, I held it by the emitter lead, got up and walked a couple steps over and touched the case to the wall switch screw. It then measured about an ohm resistance in any polarity or lead combination.

We had a product with a bipolar opamp near one edge. production said they had a very high failure rate, and demanded we change the type used. Investigation showed that the device wa right wher the assembler's thumb landed when putting the board in the chassis. Static control stopped the problem 100% in 5 minutes.

That latter was the experience every time a similar problem was noted... we finally convinced production to go whole hog on it, and both in-house failure rate as well as field reliability was documented to be better afterwards.

Sorry to pop the pretty bubble, Paul, but "the world knows better than what you wrote".

J Tiers
12-23-2014, 10:40 PM
I use static dissipative laminate benches, but... they are only that way if you keep them CLEAN and spray with the correct cleaner regularly, which I don't.

The mats are generally always good. Dirt doesn't have to insulate, it often conducts better.... not always.

A conductive bench I could not use in any way.... I'd have to cover it.

boslab
12-24-2014, 12:31 AM
Styrofoam cups sound like they make ready made Leyden jars?
Mark

J Tiers
12-24-2014, 12:51 AM
Well, I guess I have never been stupid enough to do that. I mean, really.

If you are going to do this, I would recommend one of the commercially sold static mats, which are high resistance and will not short things out or allow an instantaneous discharge which would do exactly what you are talking about with touching the light switch's grounded screw.

But again, with over 45 years of professional work in electronics, I have never had a static problem with a single device. NEVER! It can be done, but you have to try, AS YOU DEMONSTRATED!

What do you refer to that is stupid?

The mats are all high resistance protected, and usually you have a choice of non-triboelectric or actual resistive types.

It's the copper sheet that is stupid, if not insulated away from the devices and the people, as mine is. Mine is grounded, but not accessible unless specifically desired to ground something to it.

As for "you have to try".... Not quite, since the factory had many problems with static that didn't involve trying hard. They were not "trying" at all, it just happened on the production line. Both destruction on the spot, and also (but less provable) degradation that lead to later failure. Our own techs in room with concrete floor could not install 3 mosfets without blowing at least one, UNTIL they used static straps.

And I didn't try THAT hard, I just got the device in line with the static discharge. Not like I marched around scraping my feet on a carpet. Just got up and walked a few steps, and 'zap".

Frankly, I would regard working without static protection as irresponsible, at least. If the stuff being worked on is supposed to last.... But it's your choice. You are free to not believe, but I won't have you working on our stuff unless you use the straps or equivalent methods. I have SEEN the difference.

We do MIL electronics, among other things, and the inspectors really want to see straps, and folks using them. I can't blame them, it makes a difference, one I have SEEN in action.

elf
12-24-2014, 01:38 AM
On the other hand, copper makes great kitchen countertops. Studies have shown it has lower bacteria counts than other surface types (I read it on the Internet xo I know its true)

J Tiers
12-24-2014, 08:11 AM
On the other hand, copper makes great kitchen countertops. Studies have shown it has lower bacteria counts than other surface types (I read it on the Internet xo I know its true)

Silver should be even better than that..... Who's gonna be first?

Seastar
12-24-2014, 03:03 PM
I would agree that a copper sheet is a bad idea as an electronics work surface.
It will short out and damage circuits you are working on.

As for the other discussion, in my electronics manufacturing company we have a anti-static coating on the floor of the PCB assembly room that has stopped static damage in that area.
We also have anti static mats and cuffs at every work station. Always have had in our 38 year history.
I believe them to be absolutely necessary to protect the components.
The mats and cuffs have virtually stopped infant mortality in our products.
Human life depends on many of the things we design and build so we can not take chances.
Many times static damage manifests itself weeks or months after it has occurred.
Bill

Mark Rand
12-24-2014, 04:21 PM
To all the nay sayers:- A copper topped bench might be a bit risky with static sensitive electronics, but give it a good return connection and it'll be bloody good for welding on.:cool:

J Tiers
12-24-2014, 04:48 PM
To all the nay sayers:- A copper topped bench might be a bit risky with static sensitive electronics, but give it a good return connection and it'll be bloody good for welding on.:cool:

Even if you were not planning to do any welding.............. :D

JRouche
12-24-2014, 05:07 PM
Im used to working on high density fiberboard. Usually coated in some kinda "plastic" paint. One that is not too slippery, white in color for visibility of components I WILL drop :)

I like wood cause Im not into getting shocked. I kinda like the vibrating metal. But some of it burns more than moves (current VS voltage VS Freq).

As for static??? I think location is a major concern. If you are traveling around the room holding components by their delicate areas then sure, ya might want to have spares on hand. But if yer at a workbench and are careful where you put yer digits then no problem. And location like what lakeside53 said.

When I was doing field work we ALWAYS took static precautions (wrist straps). Bench work? Not so much. Just careful handling. JR

goose
12-24-2014, 05:10 PM
Don't do electronics. But I like the look of the copper. Would make a bitchin layout bench.

Rosco-P
12-24-2014, 06:14 PM
Haha Flim Flam, good to know Paul! Too late for me I'm afraid. Now I'm stuck with a nice looking copper worksurface instead of a flaky old particle board desk. Durn.

Instead of flakey old particle board, Aluminum cookie sheet for work area. For a more professional look, buy a small countertop from a used commercial kitchen supply.

lakeside53
12-24-2014, 06:42 PM
I like small ribbed "real" rubber mats. Harder to find now, but they don't melt with a soldering iron. The fake rubber (plastic) are awful for melting and static.

danlb
12-24-2014, 09:18 PM
In my experience, it is a non-existent problem. Old wives tale. Myth used to sell static control products. Flin-flam!



Reminds me of a training film I watched in the good old days (when AT&T did it's own research and development, and covered 2/3 of the USA). A little background; AT&T had several thousands of electronic switching systems. Each system was made up of thousands of circuit boards. A subsidiary (Western Electric) manufactured the circuit boards, so there was very tight control throughout the lifecycle. They found a higher than expected level of defective new replacement parts. They did a lot of research.

The training film showed how they isolated the problem to static discharge. The electron microscope showed the craters blasted in the silicon of the integrated circuits. The took it a few steps further by monitoring circuit boards that were zapped in the test but showed no signs of damage. They found that a large number of those boards failed sooner than they should have. The interpretation was that some components were slightly damaged and eventually broke down.

After the static problem was identified, we always used anti static devices, packaging and work areas. The trouble rates went way down.

To this day, I still follow proper procedures. It shows in computers that I put together that are still working flawlessly 15 years later.

Dan

Rosco-P
12-25-2014, 09:35 AM
On the other hand, copper makes great kitchen countertops. Studies have shown it has lower bacteria counts than other surface types (I read it on the Internet xo I know its true)

Sinks too!

PStechPaul
12-25-2014, 10:36 AM
Copper makes a nice bar top, especially after it has acquired a patina:
http://www.colorcopper.com/pages/Copper-Bar-Top-Photos.html

http://cdn1.bigcommerce.com/server800/488a9/product_images/uploaded_images/Azul-Bar-Top-Copper-2.jpg

KMoffett
12-25-2014, 06:52 PM
I sat in on a static damage demo by 3M many years ago. (Yes they make antistatic products.) Had an FET setup in a tester. A tech pulled the FET out of the test holding onto the plastic body. Placed it back in the tester and it showed the same reading. Another tech pulled a one foot strip of Scotch off a roll. They had a meter that measured static charges. Held near the tap, it indicated 10s of thousands of volts. The first tech pulled the FET out and the second swung the tap within an inch of it while holding both ends. Placing the FET back in the tester showed a significant drop in readings, not completely dead, but certainly way out of spec.

Ken

Mike Nash
12-26-2014, 10:10 AM
I did some contract work in Chihuahua, Mexico at an electronics assembly plant about 25 years ago. We had to wear these little straps on our shoes and tuck the end in the top of our socks. You lost when it was your day to push the rubber wheeled cart with our laptops and tools back to the area we were working. Every few steps was a "nice" little pop into the lower leg. While it made a believer out of me, I still never really became a practitioner of anti-static techniques. I do make sure I touch the case of something before handling parts though.