Specifications for
Magnetic Shielding Foil

Magnetic Shielding Foil

Weight: .004": 0.18 lb/ft²; .010: 0.45 lb/ft²
Temper: Stress Annealed
Specification: MIL N 14411c
Grain Size: 10
Hardness: HV 0.3 = 188
Coercive Force: HC = 0.005 Oersteds
Max. Permeability: MUMAX = 444000
Saturation Induction: B (10 OE) = 7600 G

Chemical Analysis:
Ni: 80%, Fe: 15%, Mo: 5% plus trace amounts of S, C, Mn, Si, & P

Attenuation is the ratio of the magnetic field strength on one side of the foil
compared to the field strength on the other side.

You can estimate the amount of magnetic field reduction (Attenuation)
produced by a cylinder of .004" Magnetic Shielding Foil of a given Diameter (D, in inches)
if you know the Permeability (P), with this formula:

Attenuation = 0.004 x P/D

For example: You would expect a 8:1 reduction (88%)
from a 10" cylinder in a 1 kHz field where permeability is about 20000 (see graph above):
Attenuation = .004 x 20000/10 = 8

Shielding Foil Installation Notes:
1) Cylindrical shapes generally provide more shielding than flat layouts.
2) Allow at least 1" overlap & achieve good foil-to-foil contact at all seams.
3) Do not solder or weld. Heating permanently reduces shielding effectiveness.
4) Spacer shims of 1/16" to 1/8" between layers improves shielding effectiveness.
5) Avoid sharp angle bends in the alloy.
6) Foil can be glued, screwed, nailed, taped, riveted or stapled to a supporting surface.
7) Use metal primer first if you are going to paint the foil.
8) Apply protective covering to all exposed edges. The are SHARP!

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