28 May 2022

Advanced EMI/thermal shielding technology for 5G applications

EMI/thermal shielding

Major players in the telecoms arena are working hard to overcome a variety of technical barriers to deliver on 5G’s potential. Among the likely outcomes of this work will be higher number of components in more compact spaces, which in turn prompts the need for effective electromagnetic compatibility and thermal maintenance solutions. Paul Dawidczyk, Global Telecom/IT Market Sales Manager, Parker Hannifin Chomerics Division looks at how advanced EMI/thermal shielding technology can help.

5G wireless technology is pledging to deliver higher multi-Gbps peak data speeds, ultra-low latency, more reliability, massive network capacity and increased availability. The resulting elevated performance and improved efficiency will empower new user experiences and connect new industries. With 5G, the full potential of the Internet of Things (IoT) can finally be realised through the connection of machines, objects, devices, and people.

Different frequency bands

The next generation 5G wireless network seen in the advertisements is not the 5G available today. To understand why, it is necessary to set out the three different signal frequency bands.

Today’s 5G is essentially an advanced version of 4G. It has a little more capability, but it operates on the same frequencies (700 MHz to 2.6 GHz). Although there is a mid-range frequency band available of 2.5 to 6 GHz, the true promise of 5G and its potential to transform the world will take place in the ultra-high frequency arena (25 to 50 GHz), close to the bottom of the millimetre wave band.

One of the problems is a general lack of definition for the ultra-high frequency range. and this is just one issue of many. For instance, short transmission lengths of metres rather than kilometres are inherent with 5G. It could be that achieving the full potential of 5G will require more local network infrastructure, perhaps in the form of micro antennas placed on building rooftops or streetlamps (small cell sites), which are likely to be more compact than previous-generation solutions. There will be considerably more transmit/receive points than with the current 4G frequency requirements.

One way to maintain a strong signal is to boost the power, but this has the negative consequence of generating heat in integrated circuits (ICs) and on printed circuit boards (PCBs). Reportedly, 5G signals even have problems negotiating obstacles such as trees in full leaf and tinted windows. Work to overcome these issues is therefore taking place concurrently with device and infrastructure development to help speed time-to-market.

5G infrastructure requirements

The infrastructure that supports the networks on which communications depend presents many electromagnetic interference (EMI) shielding and thermal management challenges. Equipment such as base stations, antenna and cabinets that house complex electronics require different technologies and materials to mitigate EMI.  In addition, unique next generation thermal interface materials (TIMs) will be required to ensure components remain within specified operating temperatures, thus supporting system reliability and longevity.

While much of the infrastructure currently in development is new to the ultra-high frequencies in which 5G will operate, leading providers of EMI shielding, and thermal interface solutions already support applications that function at these frequencies. High-volume applications such as automotive radar systems operate in the realm of 77 GHz, for instance. As a result, the expertise of how to provide effective EMI shielding and thermal interface solutions to infrastructure devices at true 5G frequencies already exists.

This is good news for telecoms solution developers, several which are currently seeking shielding requirements for frequency applications of up to 100 GHz. Why so high? Well, if the testing frequencies are up to 50 GHz, many intentional fundamental frequencies divided digital signal rates and local oscillators (LO) within the circuitry have harmonic content much higher infrequency.

Failure is costly

Inside most 5G infrastructure housings or enclosures there is a transmitter and receiver, so shielding is required to make sure one does not interfere with the other. This electromagnetic compatibility (EMC) ensures all circuitry works in harmony without interfering with each other. There are also radiated emissions requirements globally so that signals transmit via the antenna (intentional transmitter) and not random signals radiating out of the enclosure (unintentional radiation). System enclosures also must be sufficiently sealed (shielded) so that the circuity within is not subject to external interference and create a system malfunction. Any failure to implement sufficient EMI shielding could cause the device to malfunction, function at less speeds or interfere with other devices/systems.

Another significant impact on the ability to achieve sufficient shielding is that many 5G infrastructure devices are becoming increasingly smaller in size. Today, electronic enclosures typically measure around 500 x 250 x 250 mm, often with a die-cast cover acting as a heatsink. There will sometimes be an environmental/EMI seal on the outside, while inside will be all kinds of smaller gaskets and compartment shields that prevent crosstalk.

Of course, the optimum shielding solution is to resolve EMC issues by using filters and special components on circuit boards. EMI shielding via form-in-place products or extrusions is generally to resolve issues that the engineers are unable to work out. This is largely driven by cost and/or time to market. However, increasing frequencies will almost certainly drive a larger requirement for both microwave-absorbing components and traditional solutions such as conductive gaskets.

Aside from EMI shielding requirements, it is necessary to dissipate heat in tightly packed spaces so that system components continue to operate efficiently, as intended and within desired temperature ranges. The absence of thermal management can often lead to device/system failure, which is why TIM solutions such as Parker Chomerics THERM-A-GAP™ thermal gels and pads are so critical for the future success of 5G.

Beyond telecom infrastructure and devices, future applications will extend to autonomous vehicles, connected wearable technology, and solutions that replace existing wired systems for home entertainment.

Informed selection decisions

Any EMI or thermal interface solution will be subject to many of the usual parameters for projects of this nature, including thermal impedance, shielding performance, compliance, weight, cost, availability, and environmental attributes such as the ability to recycle. Ease-of-use and reliability are further considerations in the purchase decision.

With these factors in mind, working with an expert technology partner is essential, especially one that is aware of the application requirements, and which already has EMI shielding and thermal management solutions working in the ultra-high-frequency spectrum. Further factors worthy of consideration when selecting a supplier include expertise in areas such as product development, custom-engineered solutions, complete electronics housings and supply chain management. After all, close collaborations typically achieve the best project outcomes, from initial concept through to end of product life.