How Can You Solve The EMI/RFI Problems for Injection Molded Components?

By September 17, 2018
EMI Shielding Materials

As the numbers of injection molded materials keep increasing every single day, the need for EMI and RFI shielding also increases. Starting from mobile phones, laptops, medical equipment, and military electronic components to other commodities in the industrial and consumer market; all are injection molded. Knowing the widespread reach of these devices, the significance of EMI shielding is now felt more than ever for keeping up with the safety regulations, and also performance.

These components are mostly made of plastic which is a non-conductive material and this is why plastic casing cannot provide any shielding benefit on its own. EMI shielding products are designed to protect a device in two ways – first, by preventing the devices from emitting electromagnetic radiation while being caged within the injected mold and secondly, by obstructing the external waves that tend to penetrate the device forcefully,  interfering with the regular operation within the device.

Understanding the Differences Between EMI and RFI

At times, it becomes difficult to differentiate between EMI or RFI. This is solely because of the vague understanding of the terms. And as a matter of fact, both EMI and RFI are so close in the concept that they are at times interchangeable; but not always. EMI is mainly the electronic interference which causes hindrance in the daily operation of the electronic device and results in performance degradation. RFI, on the contrary, is the Radio Frequency Interference which is solely dependent on the frequency. Just like all alkalis are bases but all bases are not alkalis, all RFI is EMI, but not all EMI is RFI.

Identifying EMI Problems

Any device or component with an electrical signal can cause EMI or RFI interference. To put things simply, electric switches, radios, microprocessors, networking equipment, everything can emit electromagnetic radiation and hence requires EMI Shielding. When you bring an element with strong electronic force near your laptop or television, you might notice the screen flickering. This is an example of EMI too. At times you wonder at home why the Internet speed gets slow even when you have the best router and high data pack recharged. Also, that’s due to EMI/RFI.

Can You Find a Solution to Make the Plastic Casing Conductive?

Adding certain additives can help make plastics conductive. Since plastic is non-conductive, it lacks the natural EMI shielding capability. Using additives at times can turn out to be a costly endeavor and hence not the obvious choice of experts. Conductive coating provides an affordable and convenient solution to this problem.

Since the conductive coating method has been in use for more than two decades proving its effectiveness and reliability, many manufacturers opt for this EMI shielding process for their applications. While manufacturing the equipment which needs EMI shielding, either the entire body or some parts require specific measurements. Either the whole body needs to be plated, or the particular segment needs to be plated for effective EMI shielding.

How Can Electrolytic Plating and Electroless Plating Serve the Purpose?

There are two ways of adding conductive coatings to plastic bodies – electroless plating and electrolytic plating or electroplating. In electroless plating, the injection-molded component is sent through a chemical etching process where its outer surface is prepared for the copper-plated covering. The metal coating in this process should be of a thickness of 0.0004 inches at the least and 0.0005 inches at max. While the natural characteristics of the material remain intact, the surface layer gets affected enhancing the shielding effectiveness of the entire body.

The process of electroplating includes a material where the coating needs to be thicker than used in electroless plating. It has the thickness of 0.0002 inches to 0.003 inches and enhances the EMI shielding effect with additional metal over the initial cover layer. Generally, the metals used in electroplating are Chrome, Copper, Gold, Nickel, Silver, and Tin. When compared to electroless plating, the electroplating not only takes less time, but also reduces cost, and since a wide variety of metals can be put to use, the EMI Shielding effectiveness for injection molded part gets extended.

When it is time for you to choose EMI shielding materials for your applications, consider the market needs and industries. Whether your custom solution will be able to meet the expectations or not, depends a lot on the materials used and process applied in shielding the injection-molded components.