In 2020, the average number of connected devices was 50 per household. As the Internet of Things (IoT) continues to proliferate, a new challenge has quietly taken hold of the electronics market — The Interference of Things. More specifically, the electromagnetic interference (EMI) of things.
What Causes EMI?
EMI is a disturbance generated by an external source that can negatively affect the performance and reliability of an electrical connection. Without proper precautions, EMI disturbances can interrupt signal strength, contribute to data loss, or result in complete electrical failure. EMI occurs naturally and unnaturally, making it particularly difficult to navigate. The top two generators of EMI include:
- Electronic Equipment
EMI is inherent in all electrical devices, directly resulting from the so-called “noise” that is created through thermal agitation (i.e., electron movement and circuit resistance). The most common offenders of EMI/RFI include power lines, transmitters, and various types of electrical collectors. However, connected devices such as smartphones, smart TVs, and smartwatches, and household appliances such as microwaves also contribute to the noisiness in an environment. - Atmospheric Noise
EMI/RFI also occurs naturally via solar radiation or electrically charged rain particles. As such, any equipment that is not properly shielded can experience disruption during significant snow or electrical storms.
Braided Cables for EMI Protection
There’s more than one way to protect or "shield" a cable from EMI. The style of shielding you choose will depend on frequency levels, mechanical stressors, and other elements specific to the application environment. But one thing is for certain: given our growing dependence on connected devices, all future electronics will require some form of EMI protection.
Braided cables are a type of shielding that consists of fine metallic strands (usually copper) tightly woven together into a meshed tube-like formation. The interwoven wires wrap around the cable conductor to achieve three important outcomes:
- To deflect electromagnetic interference (EMI) and radio frequency interference (RFI)
- To strengthen the cable’s flex life and mechanical strength
- To prevent the cable from transmitting EMI/RFI to other nearby electronics
Tinned copper and silver-plated copper are the go-to materials used in braided wiring; however, product engineers can select from a list of alternatives, including:
- Pure silver
- Pure nickel
- Nickel-plated copper
- Gold-plated copper
- Gold alloys
- Monel
- Bronze
When Should You Use Braided Cables?
Even though braided cables only offer 70% to 95% coverage, they are considered highly effective at protecting against all frequency levels. This is due in part to the higher conductivity of copper (most commonly used in braided cables) and in part to the bulky braid-like design, which remediates noise. Keep in mind, braided cables can be flattened to fit into confined spaces, but they still tend to be on the bulky side and may not be suitable for all situations. The best applications for braided cables include:
- Applications involving low- to medium-frequencies
- Electrical components that must endure frequent pulling and bending
- High shock or vibration applications
- Applications involving significant temperature changes
- Short runs that require a low-resistance ground path
The electromagnetic frequency spectrum will continue to expand, creating greater demand for shielded cable and connector solutions, such as the protective lattice design of a braided cable. To help product teams determine which type of EMI shielding is right for their product application, we created a whitepaper chock-full of additional insights: Maintaining EMI/RFI Shielding in Electrical Connectors.
