EMRFD Message Archive 8396
Message Date From Subject 8396 2013-03-23 09:27:09 Jerry Haigwood Copper Tape
Has anyone on this list used copper tape for shielding? Is the
adhesive conductive? I see the stuff on ebay but since it is coming from
China, I can't get a specification sheet on it. I want to use some of this
tape to see how much I can reduce the leakage from my home made 8640Jr
generator. I don't know how strong the adhesive is but it might be useful
to make a simple layout for a board. I figure you could cut the tape to
size and stick it down to the top side of a single sided board. I am not
sure how well it would hold. I have heard of people using the tape to
repair PCBs with a burnt trace.
Jerry W5JH
"building something without experimenting is just solder practice"
[Non-text portions of this message have been removed]8398 2013-03-23 10:06:50 Dana Myers Re: Copper Tape 8399 2013-03-23 10:24:45 NeilDouglas Re: Copper Tape
Proper 'EMC' copper tape from the likes of 3Ms or Kemtron certainly has
conductive adhesive,
from Kemtrons data sheet,
http://www.kemtron.co.uk/products/emc/conductive-adhesive-tape.html
the adhesive has a resistance through the adhesive of 0.003 ohms per square
inch.
I have used it to make and modify PCB's as well as making screens by
sticking it to thin cardboard which is then bonded to the PCB or chassis
with tape or braid.
Neil
G4SHJ
_____
8400 2013-03-23 10:29:10 kb1gmx Re: Copper Tape
It is conductive. I still find for high current stuff its good to solder the edges. depends on what your doing.
Allison
8401 2013-03-23 10:31:25 Jerry Haigwood Re: Copper Tape
I have come to the conclusion that I need to buy the 3M product for
shielding. The Chinese stuff does not mention a conductive adhesive so I am
guessing it does not have any. I want to save a buck or two but probably
can't. A 6 yard roll (smallest I could find) sells for about $17 from
Digikey.
Jerry W5JH
"building something without experimenting is just solder practice"
8402 2013-03-23 12:12:25 Mike Czuhajewski Re: Copper Tape
purchase, conductive or nonconductive. It is available both ways. Why
would one want nonconductive adhesive? That version is cheaper, so if
your application doesn't absolutely require conductive adhesive (and
mine didn't) you can save money.
Example: at McMaster-Carr (www.mcmaster.com), a major industrial
supply house which also accepts small orders from home, a 6 yard roll
of 1" copper tape is $14.67 with nonconductive adhesive and $20.96
with conductive.
I've been doing some experiments recently that required small pieces
of double sided copper clad board with copper foil wrapped around the
edges to insure good grounding of the bottom side. I went to one of
the local "big box" hobby shops (Hobby Lobby) and picked up a roll of
copper tape intended for stained glass uses. I got the largest size,
which was 1/4" wide. The 36 yard roll cost $6.99 and the smaller
widths were less. The same size and length, with nonconductive
adhesive, is $12.38 at McMaster.
Since the tape was to be soldered on both sides of the board I didn't
necessarily need conductive adhesive. At that price I presumed that
it's nonconductive and didn't even bother to check it with a meter.
(And being marketed as stained glass tape, it certainly doesn't need
to be conductive.)
And why did I choose that particular hobby shop chain? I checked their
web site plus Michaels and Joann's. It was the only one that had
copper tape listed, the local stores of all 3 were closing in under an
hour, and I wanted to pick it up that night.8403 2013-03-23 12:17:47 Stewart Bryant Re: Copper Tape
See 290876030943 at the usual action house as an example.
Stewart/G3YSX
8404 2013-03-23 13:10:08 Rick Commo Re: Copper Tape
http://www.stewmac.com/shop/Electronics,_pickups/Supplies:_Shielding/Conduct
ive_Copper_Tape.html
I bought the 3 reel package for approx $30 a couple of years ago and from a
different vendor. What you get is one 180" reel each of 2", 3/4" and 1/4"
and the adhesive is conductive. For the scale that I needed it, this was a
reasonable buy.
Cheers,
-rick, K7LOG
8405 2013-03-23 13:17:30 Jim Re: Copper Tape
This stuff works great for every application you can think of. I've got rolls of the stuff in several widths, from the local stained glass shop, and even an 8 1/2 x 11 sheet. My ex-wife did stained glass and she turned me on to this. It's wonderful.
Things to remember -- the adhesive is NOT significantly conductive, so you'll need to do solder bridges where it overlaps. Also, the adhesive does not stay sticky forever, so it'll eventually fall off unless you do something like poke thru-hole components through it, on a perfboard. And when the adhesive dries up on the unused roll, you'll need to get creative with other glues, but cyanoacrylate works well. (Copper foil tape has a paper backing tape on the sticky side, and either the paper just falls off, or it gets stuck on there forever.)
Finally, you want to knock off the surface oxidation with Scotchbrite. On stained glass this is not an issue because they all use zinc chloride acid flux, but the usual rosin flux for electronics is not aggressive enough to burn through the oxide.
I'm in Austin, which is an artists' Mecca, and there's about three different stained glass suppliers nearby. You may not be so lucky, but the stuff from China is probably the same as what I have, and it pretty much all works the same.
For those who are interested, you might google on stained glass and see how it's used, and probably you'll get good ideas for electronics applications.
73
Jim N6OTQ
>________________________________
>8406 2013-03-23 13:17:31 Todd F. Carney / ... Re: Copper Tape 8408 2013-03-23 14:30:56 Kerry Re: Copper Tape
http://i50.tinypic.com/21b2lbo.jpg
The housing and connectorising doesn't have to be this elaborate of course; a much simpler arrangement could be devised.
Shafts and switches will still present a challenge but disc-shaped collars inside the front panel on shafts might help as might two-piece shafts with an insulating joiner.
This DDS generator is built in a commercial steel (Marviplate) case;
http://i50.tinypic.com/25q5a3k.jpg
The front panel is PCB material;
http://i45.tinypic.com/sv3mza.jpg
Notwithstanding the quite large cut-outs in the panel, I measure about -85dBm leakage at about 2" from the front; if the generator is kept a couple of feet away from the device it's feeding that should suffice for most work.
Kerry VK2TIL.8409 2013-03-23 14:32:55 Jerry Haigwood Re: Copper Tape
According to 3M, their 1126 and 1181 copper foil tapes have "a unique
electrically conductive pressure-sensitive acrylic adhesive." Electrical
resistance through the conductive adhesive is specified at 0.005 ohm
typical. They also state, "Conductive particles in the adhesive provide the
electrical path between the application substrate and the foil backing."
The 0.005 ohms does in fact sound significantly conductive to me. My first
application for this tape is to use it to seal my 8640Jr generator to see
just how much RF leakage I can remove. I may also use it for other things
such as prototyping but I want to try removing the RF leakage first. I
don't believe the conductive adhesive would be required for prototyping. I
could just solder the overlaps as you stated.
Jerry W5JH
"building something without experimenting is just solder practice"
8410 2013-03-23 17:43:35 Jim Re: Copper Tape
You'll find that while the 3M product is superior, it's also a whole lot more expensive. And almost always worth the extra cost.
3M stuff is ALWAYS on my "must buy" list, even with the added cost, because it always works so much better than the cheap crap. But -- at least for my needs on copper foil tape, my cheap junk from the stained glass store works just fine.
73
Jim N6OTQ
>________________________________
>8412 2013-03-23 17:43:37 Hue Miller Re: Copper Tape
Hula Hoop toys that I think might make a good basis for the tape. I also noticed at a local
bicycle shop, some local craftsperson has custom made Hula Hoops for sale, these are
in some really crazy large sizes for fans of this particular exercise. I am not quite sure
how to fix the loop to some holder; maybe a PVC pipe straight across the diameter, but
how to have it grip the loop?
-Hue Miller
[Non-text portions of this message have been removed]8413 2013-03-23 21:32:44 Steven Read Re: Copper Tape
Steven Read - ab9ol - (em79jt)
Dublin, IN
8414 2013-03-23 21:38:14 Jerry Haigwood Re: Copper Tape
They worked fine for me. I am not sure what your problem might be.
Jerry W5JH
"building something without experimenting is just solder practice"
8415 2013-03-23 22:00:35 Steven Read Re: Copper Tape
Thanks and I will try to pull them up on a computer later. This may be an issue with the handheld device I am using.
Steven Read - ab9ol - (em79jt)
Dublin, IN
8416 2013-03-23 22:09:38 Kerry Re: Copper Tape