Electronic – What’s the need for conductive bridges between the regions of a smart card contact pad

connectorsmart-card

Here's a scan of a "chip-and-pin" Visa Electron contact pad

enter image description here

It looks like a metal plate divided into regions by narrow cuts. Look for example at regions marked A and B – there's a cut between them but it only separates them partially and there's a narrow metal bridge left on the top of the cut.

That looks strange. If the regions have to be connected why not just omit the cut entirely and have one single region?

Maybe it's for cleaning contacts of the reader – as they pass over the cuts the dirt if any gets scrapped of them, but I'm not sure.

What's the reason for this design? Why are the regions partially separated by a cut yet there's a conductive bridge left between them?

Best Answer

The ISO/IEC 7816 (see part 2) standard does not define the shapes of the pads, only the minimum size:

This part of ISO 7816 does not define the maximum dimensions or shape of the contacts except for the requirement that each contact shall be electrically isolated from the other contacts.

Therefore, it is safe to assume that what you see is done just to make it look nice. You can see the same thing with the USB contacts below:

enter image description here

Related Topic