Should smartcards be affected by magnetic fields?

[Mark R]

Just wondering. My first thought was that as these were all solid-state electronic, with EEPROM/Flash memory cells, there shouldn't really be anything that would be disupted by magnetic fields. Especially not when unpowered.

These are not 'contactless' cards, but conventional ISO/IEC 7816 and ISO/IEC 7810 smartcards.

However, I had one that I used to log into an app at work. One day I put it close to a magnet, and afterwards it didn't work.

I was thinking that this was just conincidence, but someone else at work recently said the same thing: they put it close to a magnet, and then it stopped working.

So, is this coincidence? Or is the magnetic field disrupting the cards' electronics?

 

[PottedMeat]

i suppose if you moved it quickly enough through a field there are probably conductive loops where the induced current could damage transistors/traces.

 

[Modelworks]

It would have to be something stronger than your average fridge magnet. But yes placing any type of flash near strong fields can flip bits.

 

[William Gaatjes]

Can Fram or Mram chips be affected by strong external magnetic fields ?

http://en.wikipedia.org/wiki/Ferroelectric_RAM.

http://en.wikipedia.org/wiki/MRAM.

 

[Cogman]

It would have to be something stronger than your average fridge magnet. But yes placing any type of flash near strong fields can flip bits.

Generally with solid state memory, it isn't necessarily the strength of the magnetic field that flips the bit, but the motion of the material through the magnetic field.

moving a flash drive through a strong magnetic field induces a current which can flip bits. (or fry circuits if the field is strong enough)

 

[Mark R]

moving a flash drive through a strong magnetic field induces a current which can flip bits. (or fry circuits if the field is strong enough)

Guessing it was probably this.

It was quite a strong magnet (*) - so I wonder if it actually damaged the card, instead of erasing it.

I might have to try an experiment with an old USB stick.

(*) 3 Tesla, cryogenic helium cooled superconducting electromagnet

 

[bobsmith1492]

Guessing it was probably this.

It was quite a strong magnet (*) - so I wonder if it actually damaged the card, instead of erasing it.

I might have to try an experiment with an old USB stick.

(*) 3 Tesla, cryogenic helium cooled superconducting electromagnet

Yes, one might say that is a strong magnet. One might also manage to understate things.

 

[bobsmith1492]

Guessing it was probably this.

It was quite a strong magnet (*) - so I wonder if it actually damaged the card, instead of erasing it.

I might have to try an experiment with an old USB stick.

(*) 3 Tesla, cryogenic helium cooled superconducting electromagnet

Yes, one might say that is a strong magnet. One might also manage to understate things. I hope you have no steel rods in your leg...

 

[Modelworks]

Generally with solid state memory, it isn't necessarily the strength of the magnetic field that flips the bit, but the motion of the material through the magnetic field.

moving a flash drive through a strong magnetic field induces a current which can flip bits. (or fry circuits if the field is strong enough)

Depends on how strong the field is. If it is strong enough no motion is required. Of course those levels also cause things like frogs to levitate

 

[Ken g6]

If it is strong enough no motion is required.

Some motion, as defined by Maxwell's equations, is practically required. Either the flash drive is moved into and/or out of the magnetic field, or the magnetic field is turned on or off with the flash drive near it.

Unless the flash drive were somehow manufactured in the magnetic field and it was never removed; but that's not practical. And in that case plugging in the drive might fry the computer you plugged it into!

 

[Matthiasa]

Yeah motion would be needed, or a change in field strength... well flux densities but yeah. Good thing is though the fact it was placed in the field means it was moved or the field was changed(switched on).