Injection moulding specialised materials

Injection moulding specialised materials

Injection moulded EMC and RFI parts
Many injection moulded parts and assemblies require the use of specialised materials or surface finishes that provide specific properties. These include the ability to control or prevent radio and electromagnetic interference: EMI and RFI.

We have considerable experience working with specialised and exotic materials for injection moulding. In particular, we have learnt which materials work best for particular applications, how best to ensure the optimum mechanical and chemical properties, and which injection moulding techniques offer the most effective combination of performance, productivity and cost.

Integrating EMC and RFI properties in injection moulded parts
By integrating special coatings into the injection moulding and finishing processes we are able to create a range of part characteristics to meet the needs of a wide range of applications, from medical systems to electronic instrumentation.

EMC and RFI shielding
It should be noted that although the terms EMI and RFI are sometimes used interchangeably, they describe different aspects of the same phenomenon. In simple terms, EMI, or electromagnetic interference, covers any frequency of electrical noise or disturbance, while RFI, or radio frequency interference, is a subset of electromagnetic noise that occurs within the overall EMI spectrum. EMI and by default RFI can occur naturally, such as lightning discharges or solar radiation, or be man-made.

In injection moulded electronics systems, electromagnetic energy is either emitted direct from electrical systems and components within the device or conducted through circuit tracks or power cables. The frequency range for radiated electromagnetic energy is normally found between 30 MHz and 1GHz, and between 10 KHz and 30MHz for conducted energy.

Electromagnetic compatibility (EMC) is a measure of the way in which a device can operate as intended without affecting the operation of other devices. There are various international EMC standards that are normally used when designing and testing electronic equipment.

How we engineer EMC an RFI compatibility into injection moulded parts
Most electrical and electronic equipment will use component parts that are manufactured to the relevant EMC standards; they should, therefore, be designed to eliminate or minimise the risk of radiated or conducted electromagnetic energy. In addition, however, it can be important to engineer in further protection by using special EMI or RFI coatings, formed within the injection moulded enclosures or casings.

We use a range of advanced coating materials from specialised suppliers. These act as a shield either by frequency reflection or frequency absorption, and typically span the frequency spectrum from 50 Hz to 2.0 GHz; options are available for other frequencies.

As an example, we use a copper conductive colloid material to provide precise EMC protection. This incorporates silver-coated copper particles and conductive resins to provide a conductive layer that is compatible with a wide range of plastics and resins. It ensures effective shielding against radiated RFI and EMI and can also be used as a ground plane to protect equipment from electrostatic discharges.

All materials are fully compliant with EMC standards.

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