Several electronic devices are present all around us and all these electronics produce some signals and noises. With the ever-increasing number of electrical devices, electromagnetic interference (EMI) and radio frequency interference (RFI) have become serious concerns. These EMI and RFI are responsible for disrupting electronic devices, equipment, and systems that are used in critical applications. As such, shielding has become imperative. To understand what shielding is, we must first understand what EMI/RFI is.
What is EMI/RFI?
Every electronic device present around us emits some magnetic and electrical energy. These are known as electromagnetic interference (EMI) and in the case of radiofrequency, it is addressed as radio-frequency interference. If not controlled, this energy comes in the contact of another device and causes it to malfunction. Some sources of interference include radios, televisions, motors, appliances, radar transmitters, static electricity, and lightning. These sources can impede the performance of devices like computers, microprocessors, navigation systems, etc.
These interferences may cause temporary disturbances, as well as data losses and system failure or even loss of life. The causes of EMI are numerous and include both man-made and natural sources. The EMI/RFI interferences are of two types- Narrowband and Broadband. These interferences can cause a disturbance with electronic devices and limit the effectiveness of a circuit within the device. So, it becomes crucial to shield devices to protect them from the effects of EMI/RFI.
What is EMI/RFI Shielding?
The shielding effect is based on a principle used in a Faraday cage. To control EMI, the circuit is designed in a way to prevent disruption, known as Electro Magnetic Compatibility (EMC). EMC Shielding is a method used to protect an internal signal from escaping and prevents external electromagnetic signals from entering the circuit. The shielding material covers the PCB elements such as IC chips and active components, or connectors and cables between PCBs. The EMI/RFI shielding agents include acrylic-based sprays or paints that are applied to electronic housings. The shielding spray of pure metals such as copper, silver, and nickel is used to help eliminate the EMI/RFI interference.
EMI shielding materials include flexible metal screens, metal wires, and metal foams. The most popular option these days is using housings for electronic equipment. It is becoming popular because plastic is an economical and good insulator. The plastic housing coated with a conductive layer works as a shield to block the waves. The coating method is more feasible because it is easier, as well as effective.
The purpose of shielding is not only to prevent outside signals from entering the device but also to make sure that your device isn’t doing any of the interfering. To achieve these objectives, EMI/RFI sprays, EMI gaskets, shielded windows, and more are used to help avoid the radiation of frequency waves interfering with other electronic sources. Shielding is crucial for equipment used in military, aerospace, medical, fluid sealing, environmental and microwave applications. Shielding helps in avoiding issues ranging from a simple communication disturbance to disruption of a safety-critical signal.