Saturation:
The magnetic saturation of the shield is given by the magnetic properties of the shield material.
Ferromagnetic material saturates between 0.5 and 2 Tesla. Once the shield is saturated, its apparent Permeability will decline to the value 1, meaning that the shield acts like air. A saturated shield does not guide nor attract magnetic flux lines. Therefore, the shield design has to be chosen such that the field generated by the current and the field generated by external sources do not saturate the shield material.
General Principles of shield Designing:
In the following sections we will describe how the different geometries influence the Shielding Factor, Magnetic gain and Saturation level.
Influence of Width W:
View | Influence |
 | W has an influence on the magnetic gain and also on the Shielding Factor. We recommend choosing W as small as possible. The magnetic gain and the Shielding Factor are reciprocally proportional to W. |
Influence of Length L:
View | Influence |
 | L has an influence on the Shielding Factor. We recommend choosing L as big as possible. The absolute minimum of L is the length of the part (visible in blue). The maximum is open, but 8mm more than L is sufficient. The Shielding Factor increases with the length of the shield L. Once the shield is long enough, approximately the length of the part ( l +8mm), a longer shield will not improve the Shielding Factor significantly. |
Influence of Height H:
View  | Influence H has an influence on the magnetic gain and on the Shielding Factor. We recommend making H' (from the top of the PCB surface to the end of the shield) about 10mm. The absolute minimum of H' is about 6mm (visible in blue). The maximum is not relevant, but the shielding effect will not increase significantly for a shield with H longer than 15mm. It is important that both sides of the shield have the same height H. The Shielding Factor increases with the height of the shield H. Once the shield is high enough, approximately 15mm, a higher shield will not improve the Shielding Factor significantly. |
Influence of the Thickness t :
View | Influence |
 | t has an influence on the saturation level of the shield. We recommend making t minimum 0.8mm. Once the shield is thick enough, the increase of the thickness will not improve the saturation level anymore. In the most of the case a shield thicker than 2mm is not needed. The saturation level increases with the thickness t of the shield. Once the shield is thick enough a increase of t will not improve the saturation level. |
What we can Offer:
Shields which are punched & bent or punched and deep drawn for various applications like electricity meters, electronic control protections in automobiles, avionics, medical devices, audio devices.
Neodymium Magnet shield
Neodymium Magnet shield
Magnetic Shielding
With our long experience in electromagnetic engineering and metallurgical knowledge, we are able to offer a complete range of magnetic shielding solutions; from small cans of 12mm diameter or less, up to room size shields which can be supplied in kit form or assembled on site at customer premises.
Magnetic Shields has the facilities to supply all your requirements. From individual multiple layer shields capable of screening down to the very low levels that are typically required in research applications, to high volume production runs of over 50,000 pieces a week for commercial industry.
Our magnetic shields are only produced from the highest quality grades of mu metal to ASTM A753 Alloy 4 and are magnetically annealed in a hydrogen atmosphere to ensure optimum performance and reliability.
Working in close partnership with our clients ensures that all aspects of your requirements are met; from design assistance, rapid prototyping and manufacturing, we are here to help you every step of the way. This ensures a product reflecting the high standards of quality, design and value that world leading manufacturers require.
Magnetic Shields is perfectly situated logistically in the South East of England for fast transportation of goods by road, air or sea, to anywhere in the world.
