PCB Shielding Cans: What You Must Know

Metal enclosures and EMI shielding techniques call for outstanding engineering skills to control harmful electromagnetic inferences affecting electrical and electronic devices. Shielding at enclosure level can prove both expensive and complicated, adding to the assembly and material costs. However, there are ways to handle EMI problems simply and economically with board level shielding. With printed circuit board (PCB) shielding, you can selectively apply cans to the intricate areas of an electrical circuit. This way, you can easily manage components with harmful emissions that are extremely damaging or sensitive.

PCB Shielding with Cans

The cans that you use are small metal boxes that you can fasten into place just like other board level constituents. With this method, you can easily manage electromagnetic compatibility (EMC) problems without compromising on product appearance and maintenance. Where protection of electronic devices is a precondition, and you need to address the EMI problems, board level shielding will need the optimal performance from cable filters as for enclosures. With the easy integration of filters to the circuit board, you can cut back on assembly and component costs to a considerable extent.

Design Issues

Though metal cans make board level shielding simpler and cost-effective, a few design issues need addressing. They are:

Can material: Shielding products work by absorbing and reflecting electromagnetic fields. Copper has good conductive properties, and it is essential for reflection and shielding above 100MHz. Both nickel and steel exhibit high permeability that is crucial for absorption and is important for shielding below 100MHz. Tin-plated copper is ideal for shielding above 200MHz while tin-plated steel is best below 100MHz. Tin plating makes soldering simpler. Aluminum is hard to solder and therefore it does not find an application in board level shielding. The other shielding materials used are stainless steel, nickel silver, and brass. Thicker metals are effective for shielding. For example, 0.2mm steel is good enough for 40dB shielding above 500 kHz if there are no significant apertures.

Ground plane: Solder a PCB can to a ground plane found under the constituents requiring shielding to design a full six-sided metal casing or a small Faraday Cage. The ground plane should not have any large gaps or apertures.

Apertures: Apertures like holes for adjustments, wires, construction seams, and indicators often affect shielding effectiveness and performance of ground planes. It does not depend on how narrow a gap is. In fact, the impact of an aperture depends on the reduced frequencies and the required shielding performance.

Cans and screens: Mounting screens provide effective EMI or RFI shielding for high EMC in sensitive devices or applications. Opt for screens and cans that are precisely designed, cost-effective, and come with a range of options and sizes. The mounting screens are more affordable than enclosure screening. Enclosure styles may have PCB cans and frames with or without fingered lids. With adjustable fingered lids, you can access the contents of the enclosure together with high attenuation.

Look for an EMI shielding product manufacturer specializing in board level shielding, gaskets, cans, and enclosures for electronic devices. The company must have the right knowledge and expertise to provide custom solutions for a range of electrical, electronics, and mechanical engineering applications.

Elvis Moore is an active blogger with an extensive industry experience in the field of electronics and technology.