An Introduction To Board Level Shielding

For better or for worse, we are becoming increasingly dependent on a plethora of mobile devices. The proliferation of these devices has contributed to a high level of electromagnetic radiation in the environment. A gadget’s electrical circuits are hugely affected by electromagnetic energy emitted by other devices in the vicinity. Electromagnetic interferences (EMI) may prevent the equipment from working in its intended fashion, ultimately resulting in the degradation in the performance. Board level shielding solutions are designed to keep circuit boards – the nerve center of any electronic or computer system – immune from these kinds of disturbances. By providing a protective layer surrounding the electrical circuits of these devices, Board level shielding helps isolate the circuitry from the other sensitive components of the device and all of them stay protected from electromagnetic invasion. This in turn helps minimize the device’s EMI susceptibility without compromising its speed or performance.

An Introduction To Board Level Shielding

How Board Level Shielding Works

Board Level Shielding is placed around the components or electrical circuits of a printed circuit board of a device that needs to be shielded. This helps restrict the flow of electromagnetic energy to and from the source and the receptor. They can be manufactured in a variety of shapes and sizes to meet different application needs. Shields are attached to the circuit board via specialized attachment mechanism. The shields typically have metal coating on the outside surfaces in order to minimize air gaps.

Factors Deciding Board Level Shielding Efficiency

Distance from the Source

Shields should not be placed too far or near the EMI source. If placed in the near-field of the source, the frequency, configuration and position of the source may affect the shield’s performance. Many things including grounding techniques, the coupling of source to the element, the effect on elements due to mutual coupling should be considered.

Shield Layout

Board Level shielding efficacy is dependent upon the design of the printed circuit board’s mounting area. A few other factors such as spacing of holes and the traces that extend from the shielded area to the other board components are also deciding factors.

Level of Heat Generation: Faster devices generate more heat which makes thermal management an important consideration. Features such as thermal pads and heat sinks are incorporated into the design to optimize shielding effectiveness.

Cavity Resonances: Resonance effect is a common occurrence in higher frequencies. Self-resonance of various structures leads to coupling which might affect shielding properties. Even when the coupling is weak, it might generate strong oscillations at high frequencies, which in turn might couple to the other parts of the enclosure.

Features To Look For In Your Shielding Solution

Traditionally board level shields have been designed as five-sided cans. However, as the wireless devices are shrinking in size, yet increasing in complexity, these shielding solutions are undergoing rapid evolution. Depending on your application needs, you can choose from one-piece, two-piece, or multi-compartmental shields. Companies today offer many customized solution if your application needs more than the standard off-the-shelf products. Many, such as a 2-piece design (fence and cover) and accommodate a wide range of surface mount or through-hole application requirements. However, if you need more flexibility, help is at hand. Your custom-made board level shielding can even enable you to incorporate many internal cavities that have the same cover and common walls. Nickel silver, cold rolled steel, copper and brass are often the material of choice. Beryllium copper offers spring qualities and is also commonly used.

When it comes to board level shielding, today’s versatile solutions are designed to solve a plethora of shielding challenges in terms of size, weight, manufacturability and performance. Choose the right solution to ensure optimum performance of your electronics and computer systems.

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