What is EMI Shielding?

Electromagnetic Interference (EMI) shielding is a process that allows you to protect sensitive parts from potential issues that could arise due to close proximity to electromagnetic fields.

EMI can disrupt all manner of devices, from military equipment through to cellphones. It can have a negative effect on medical equipment, navigational equipment, and even the touchscreens used by tablet computers. Moreover, it’s often difficult to locate the source of the EMI, as it can come from both natural and man-made electromagnetic fields. As a general rule, anything that can create an electromagnetic field may also be able to create EMI.

Issues stemming from EMI can range from the simple, such as a temporary disturbance in an electrical device, through to disastrous issues, such as the massive loss of data or a critical systems failure. As a result, it’s crucial that you protect sensitive parts and devices from EMI.

EMI shielding allows you to do that.

EMI Shielding Methods

We use one of two methods to shield your parts from EMI:

Vacuum Metalizing

This process involves the vaporization of a metal, with the vaporized metal then being applied to a part’s surface. We use a vacuum chamber to direct the flow of the metal vapor, which ensures we apply an even coating.

Typically, this method requires extensive pre-tooling, which allows us to prepare the parts for shielding. However, this method also allows for large-scale production runs that coat many parts. We’re also able to apply a top coat to the metallized part, which can enhance its EMI shielding further.

We usually use aluminum for this process. This is because aluminum forms an oxide layer around the part, as well as ensuring conductivity where needed. However, it’s also possible to coat your parts in silver, though this comes with a higher cost.

Electro-less Plating

We undertake a complex process that allows us to apply a metal coating to the part. Typically, we use this process for rigid plastic parts that offer low conductivity.

First, we immerse the part in an acid mixture in a process referred to as etching. This step causes an array of tiny holes to form across the surface of the part. We then remove the part from the acid bath and immerse it into an alkaline solution to restore its neutrality.

Following this, we apply a catalyzing film to the part and immerse it into a special solution that’s designed to accelerate the plating process. Finally, we apply a plating of copper or nickel to the part.

Which Should You Choose?

The method that’s best for you usually depends on the size of the part. Vacuum metalizing usually costs less than plating. However, the vacuum chamber used in the process place limitations on the size of the parts that you can shield.

Electro-less plating does not come with those size restrictions. However, it’s a more costly procedure.

We will discuss your requirements with you before selecting the best method for your needs.

Why Do I Need Shielding?

Though most engineers design circuits with the issue of EMI in mind, it’s not always possible to provide the level of shielding needed. The use of certain parts may prevent the circuit from achieving the ideal level of efficiency, which makes the EMI shielding process a necessity.

Why Can’t I Use Metal Enclosures?

One of the older methods of EMI shielding, metal enclosures are as the name suggests. They’re essentially sealed metal boxes that you place a sensitive component inside.

The problem with this solution is that it’s become less tenable as the size and weight of the typical electronic device has fallen. The weight of a metal enclosure would have drastic effects on the weight and size of cellphones and similar devices. Plating and vacuum metallizing offer the same benefits with none of the weight disadvantages.

What Other Benefits Are There?

Beyond protecting the device from the potentially disastrous consequences of EMI, the shielding process offers further advantages. It improves the quality of the device’s internal circuit. This makes it more efficient and can often boost the device’s speed.

Moreover, the shielding process can also reduce the amount of EMI that the device itself produces.