Why You Should Invest in Better Board Level Shielding

Posted by Irene Simpson on August 25th, 2017

In a circuit board, many components work in cohesion and build a seamless working module. Often one or many elements in the circuit become susceptible to the Electromagnetic Interference (EMI). To curb this problem not only identifying the ‘suspect element’ is necessary but also shielding the likely ‘victim’ component is a must. The primary goal of board level shielding (BLS) is to safeguard components, reduce crosstalk, and eliminate EMI susceptibility without compromising system speed and security. To this end, BLS uses engraved metal casings that shut in the integrated circuit (IC) from five sides. They work as a Faraday cage around the component. BLS is mostly custom-made because the design has to be integrated with the size of the component of the system. Off-the-shelf pieces are also available to cater to the affordable electronic market.

How is BLS Integrated into a Circuit?

In printed circuit boards (PCB), BLS provides the most comprehensive and affordable shielding from EMI. Perforated metal casings used as BLS are soldered to the surfaces of PCB. The protective casing is placed directly over the electrical components that need a safeguard. BLS enclosures, which offer a very high level of shielding, are mostly made of metals such as stainless steel, tin or zinc plated steel, tin-plated aluminum, brass, beryllium-copper, and nickel-silver alloys.

Blocking the Suspect, or the Victim, What is the Best Policy?

There are two ways a designer can integrate a BLS in their design.  They can either shield the noisy component that emits disruptive frequency or enclose the components that are highly susceptible to EMI crosstalk. Suppose, a designer is trying to build a design with low EMI output, and s/he has one radio-frequency emitter in the vicinity of an IC that will store critical data for functioning. In this scenario, the designercan either shield the IC, or she can block the RF emitter with BLS. S/he can ideally do both, but s/he will choose the one that will guarantee an effective output. S/he will need the radiofrequency (RF) emitter to function at its peak, and shielding it with BLS will hinder its working. So, s/he must shield the IC data storage, and keep the element safe from both RF hindrance and EMI. But, if in the board the power supply element was emanating EMI, then for efficient working of the circuit, s/he will shield the power supply or any other similar components. Normally the best practice is to build a design that creates minimum hindrance while maximizing the output.

What Makes the Best BLS Solution?

There are a few things to keep in mind while choosing a BLS product for your circuit board. The applied BLS should be accessible and pliable.  The frequency of the shielded component is another point to consider; the components with higher frequency need a shield with a small aperture, while the low-frequency elements would require just the opposite.

Weight is also another issue in BLS designing, especially when it comes to gadgets like a smartphone, electronic watch, and tablet, the reduced size of the circuit is not only in mandate but also necessary. For this reason, lighter metal like aluminum, which is a good heat conductor, is used to construct the BLS. If the circuit heating is an issue, like a CPU of a laptop, then steel might be a better option for BLS as they help dissipate heat very rapidly.

EMI is the necessary evil when it comes to sophisticated circuit building. High-end board level shielding provides an excellent solution to EMI issues.  As the era of nano-sized electronic technology has taken off, BLS has become an integral part of a great electronic design.