EMI and Magnetic Shielding

What is EMI?

Electromagnetic interference (EMI) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. These effects can range from a simple degradation of data to a total loss of data.

Anywhere there is a rapidly changing electrical signal, you will have EMI. Electrical currents and changes in electrical currents produce magnetic fields. Magnetic fields, in turn, produce electrical currents that can lead to interference in sensitive equipment.

  • Cell phones generate EMI that can disrupt hearing aids.
  • Electrical wiring and the switching of inductive loads to drive electric motors in hybrid and electrical vehicles (EVs) can interfere with sensors and electronics.
  • Multiple electronic systems are being combined into smaller and smaller spaces and interacting with each other to cause performance issues.

From electronics tasks like manufacturing small parts for audio earphones that deliver high audio quality in the most extreme conditions, also we can fabricate intricate geometries components for aerospace or surgical devices, with astonishing precision and lower cost than traditional machining processes.

EMI Shielding

RF shields act to block or reflect RF signals. EMI or Magnetic shields absorb and redirect the magnetic energy. Essentially the shield conducts the interfering signal around and away from the protected electronics or sensor. The effectiveness of an EMI shield is determined by the Shield Factor. Shield Factor is the ratio of the strength of the magnetic field outside the shield compared to the strength of the field inside the shield. The Shield Factor is determined by:

  • The shape of the shield - Spherical is better than cylindrical, cylindrical is better than square, square is better than nothing.
  • The Shield material - Custom alloy (soft ferromagnetic material that is 80% Nickel with iron and molybdenum) has high permeability material and low hysteresis which is ideally suited for EMI and Magnetic shielding. Custom alloy is also referred to by ASTM A753 and MIL N-14411C standards.
  • Thickness of the shield – Thicker shields will provide a better shield factor.

The FloMet Solution

Using FloMet’s unique Metal Injection Molding Process (MIM), we can provide a wide variety of shapes to match the size and geometry of the required application. By matching the geometry of the electronic package or sensor, the total real estate can be optimized. MIM can produce custom shields with features that other technologies cannot match.

FloMet’s Custom Soft Magnetic Alloy material is optimized for the MIM process. Our sintering operation is capable of producing the highest permeability that the material can offer. For other applications we can formulate hybrids of this alloy or use a variety of other materials.

Because FloMet molds these shields to meet custom requirements, we can produce shields with a wide range of wall thickness. Flomet's thin wall technology can produce shields with 0.010” thickness or less.

In summary, FloMet produces custom EMI and Magnetic shields and our technology offers a wide range of options not available with other technologies.