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This website has a calculator used to determine the resistance of conductive ink traces. http://circuitcalculator.com/wordpress/2006/06/14/conductive-ink-traces/

The calculator lets you put in the values for trace width, length, thickness, reference thickness (as specified in the data sheet of a given conductive ink), and sheet resistivity (also specified in the data sheet of a given conductive ink).

The data sheet on this website gives the sheet resistance of a conductive ink. https://www.dycotecmaterials.com/wp-content/uploads/2019/02/Dycotec-DM-GRA-9100-Datasheet.pdf

The Wikipedia page on Sheet Resistance says “Sheet resistance, often called sheet resistivity, is a measure of resistance of thin films that are nominally uniform in thickness.” https://en.wikipedia.org/wiki/Sheet_resistance

This entry on Wikipedia seems to be saying that sheet resistance and sheet resistivity are used to mean the same thing - so can I use the value for sheet resistance given on the data sheet as the value for sheet resistivity in the calculator?

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    \$\begingroup\$ IMO the difference between resistance and resistivity is in the units, and that 'Sheet Resistivity' is probably the technically correct term to use when describing the bulk characteristics of the material and would be properly expressed with units Ω·cm for sheets of a known thickness. 'Sheet Resistance' would be the resistance of a particular sheet of material with both known thickness and known area, and would be properly expressed with units of just Ω. \$\endgroup\$
    – brhans
    Commented Oct 8, 2020 at 15:30
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    \$\begingroup\$ @brhans, the overall resistance of a sheet doesn't depend on the area of the sheet, it depends on the shape. \$\endgroup\$
    – The Photon
    Commented Oct 8, 2020 at 18:45

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Both of your links give the resistivity or resistance in the correct units of ohms per square.

The bulk ink will have a volume resistivity given in ohms/metre. When printed at a specific thickness into a sheet, the sheet resistivity is then given in ohms/square.

It should be obvious with a little thought, and the way series and parallel resistances combine, that an area of film two squares long and two squares wide has the same resistance from side to side as a single square.

If you take a trace that is 10 times as long as it is wide, it will have a resistance of 10 times the ohms/square of the film.

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