Shielding circuit with plastic magnetic sheet ?

[BravoV]

As the elastic magnetic sheet is available quite cheaply with relatively large surface area, wonder if a circuit is encased or fully shielded with these sheets will reduce EMI / RFI exposure ?

Any insight will be appreciated.

[T3sl4co1l]

Y'mean the fridge magnet stuff, or actual soft magnet stuff?

Tim

[plazma]

Should you use flexible ferrite sheet instead?

[ocset]

As the elastic magnetic sheet is available quite cheaply with relatively large surface area, wonder if a circuit is encased or fully shielded with these sheets will reduce EMI / RFI exposure ?

No i dont think you can do effective B field shielding with thin pieces of sheet. -Think of the thick foam things they put on the  walls of EMC chambers...they are thick foam, and not thin sheet.

If its thin sheet, then for E field shielding it should be metallic.

[BravoV]

Y'mean the fridge magnet stuff, or actual soft magnet stuff?

Tim

Like this for example.

[T3sl4co1l]

Ah.  Yeah, no... that's magnetized, hard ferrite.  Permeability of about air.

Or, more correctly: a modest (average) permeability, but only when you drive it hard enough to remagnetize it; in which case it will quickly melt, because all that magnetic energy is lost as hysteresis.

There may actually be a little (small signal) permeability, no idea.  It's not going to be useful though...

There's no fundamental difference between that, and the stuff that's useful to us -- ferrite of either kind is cheap, just mix it in and go.  But they have to make a metric shitton of it, to get the price that low.  An easily-magnetized (soft) ferrite isn't very useful to consumers, so it's not made in that kind of quantity.

Tim