Resistance of double sided adhesive conductive carbon tape

[Chengjun Li]

Hi,

Is anyone familiar with conductive tape? I thought conductive tape should have a resistance very small. And the supplier said it has a resistance of less than 5ohms/square.
http://www.2spi.com/catalog/spec_prep/cond_adhes-tapes.shtml
But I took a measurement today. I use a small part of conductive tape to connect two pins of a blank chip carrier. The resistance I measure is around 500kohm!! I measured many times on using different methods, I am sure the resistance of the conductive tape I use is on the order of kohms.

Why?

 

[davenn]

the big question is .. per square what ?? inch, cm, metre, yard, apples ?????

their stated spec means nothing

 

[duke37]

It does mean something.
Take square of 1 unit giving 1Ω
If you now take 100 such squares, put them into a square you have 10 in series giving 10Ω and 10 rows in parallel getting back to 1Ω.

The size of the squares is not relevant. Where do you get square apples?

 

[Arouse1973]

Yeah Trevor's right. Also it's not very accurate measuring with two probes. I have always seen it done with 4 probes.
Adam

Here you go

 

[duke37]

I think the measurement should be made from one edge to the opposite edge. Using a small diameter probe would give too high a resistance reading.

That looks like a good square meal.

 

[Colin Mitchell]

The conductive foam tape I bought has channels of carbon from top to bottom and the resistance from one channel to the next is 500k.