How Do RF Shielding PCBs Handle Thermal Expansion?

RF Shielding PCBs Handle Thermal Expansion

Electromagnetic interference (EMI) can dramatically degrade a PCB circuit or prevent it from functioning altogether. It results when conductive signals, such as those produced by power and ground planes, radiate off the surface of the board. This radiation can interfere with other electronic components in the vicinity and cause them to work against each other instead of together. PCB RF shielding prevents electromagnetic radiation by creating a Faraday cage that effectively blocks the transmission of radio frequencies and electromagnetic waves. A number of techniques can be used to minimize EMI, including good PCB layout practices and reference plane design.

RF shielding for PCBs is accomplished by soldering a metallic frame or fence around the area of the board that requires protection. The frame is attached to a cover, which completes the Faraday cage, by means of a conductive grommet. The frame and cover can be constructed of different materials, although aluminium and copper are typically the most effective. The choice of material depends on the ability of the shield to reflect or absorb radiation, as well as its conductivity, solderability, and cost. The frame and cover also need to meet stringent co-planarity specifications in order to be reliably soldered to the PCB. In addition, the frame needs to be free of cross members, which obstruct inspection and rework.

There are various RF shielding methods available for PCBs, including frame and cover, shield-and-frame, shield 1-piece, and shield 2-piece. The type of RF shield required depends on the characteristics of the circuit that generates the most radiated energy. It is important to test the prototype to determine the sources of radiated energy and its size, then select the best rf shielding pcb style and material that will perform at this level. The dimensions, mounting method and ventilation of the shield also play a role in its effectiveness.

How Do RF Shielding PCBs Handle Thermal Expansion?

Depending on the specific application, a metal RF shield can be made of various materials, including aluminium, brass, nickel, silver, or steel. A precision stamper can provide expert advice on the optimum combination of material, permeability, solderability, thickness and weight to create the perfect protective shield for your circuit.

In order to work efficiently, a shield must be completely enclosed with no gaps or openings. Various types of apertures can interfere with the performance of an EMI or RF shield, such as holes for adjustments, indicators and wires, construction seams, and gaps between a shielding can’s reference plane connections. Each of these can reduce the shield’s effectiveness and require it to be redesigned.

The mechanical bend capabilities of a flexible RF shielding design should also be considered, as this will influence the maximum bend radius and type of bend requirement. Using an ultra-thin, highly conductive shielding material like Silver ink can greatly increase a flex circuit’s minimum bend capability without sacrificing its ability to transmit signals. This will allow the flex circuit to be used in a variety of different applications and locations, including car infotainment systems that incorporate GPS displays, radio and wi-fi, and vehicle navigation features.

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