Due to the continuous increase in the number of electronically controlled devices emitting electromagnetic radiation, legislation regulating the emission of (excessive) Electromagnetic Interference (EMI) is becoming increasingly stringent. On the other hand protecting sensitive electronic components from incoming electromagnetic interference has become more important as well.

Proper design in terms of grounding and selection/placement of components is the first measure one should take in order to prevent the reception and emission of electromagnetic interference. When these measures are not sufficient to meet the applicable regulations, when proper operation of the device is unachievable or when the methods used are not economical, then turning the electronic device enclosure into a Faraday cage is the way to proceed.

Traditionally such enclosures are constructed using metal or metallized thermoplastics. However, at the Wittenburg Group we have developed an EMI/RFI-shielding compound which is an excellent alternative.

EMI/RFI-shielding compounds are thermoplastic polymers, modified with electrically conductive fillers (typically carbon fibres, stainless steel fibres, nickel coated carbon fibres or multi-wall carbon nanotubes), in order to provide Electromagnetic Compatibility (EMC). Normally the volume resistivity of these compounds varies between 10^-2 and 10¹ ohm·cm.

In order to meet your exact application requirements with a single material, other additives and fillers, like flame retardants, reinforcing fibres, lubricants and colourants, can also be incorporated.

Although in principle our EMI/RFI-shielding compounds can be based on virtually any thermoplastic polymer, they are mainly based on (but not limited to) amorphous polymers like ABS, PC/ABS and PC for use in enclosures.

Compared to metal enclosures, the benefits of our EMI/RFI-shielding compounds are obvious:

• Reduced weight (especially important in portable devices).
• Design freedom, enabling you to create complex geometries, allowing part consolidation and fastening options.
• Inherently better corrosion resistance.
• Cost-effective because of reduced assembly costs.

Compared to thermoplastic polymer enclosures which are coated on the inside with a conductive coating, other benefits from our EMI/RFI-shielding compounds become important:

• Shielding performance of our EMI/RFI-shielding compounds is an integral property whereas scratching the conductive coating of a coated enclosure may lead to a shield failure.
• Better recyclability (stripping process used for removing the conductive coating creates metallic “sludge” which must be discarded.
• Lower lead times as application of the conductive coating is a secondary operation which is often done externally.
• No need for special handling during moulding our EMI/RFI-shielding compounds whereas parts which need to be coated must be kept free from contaminants for the coating to adhere properly.
• Reduced cost (as a rule of thumb up to a part weight of approx. 500 grams).

Please contact our engineers to solve your needs for EMI/RFI shielding.