While 5G handset markets will grow volume demand for ceramic capacitors, the diverse embedded industrial and automotive applications that emerge to exploit 5G’s capabilities will drive technical advancement among specialty component types.
Demand for passive components grew significantly in 2020 and continues to grow in 2021, despite the pandemic’s threat to economic growth in general. Some of this increase has been attributed to 5G handsets beginning to be manufactured. As public 5G networks start rolling out, the industry needs to prioritize putting suitable devices into subscribers’ hands now. The new models require more components, such as multi-layer ceramic capacitors (MLCCs), for purposes like decoupling power rails and balancing antenna connections. Whereas a typical 4G+ smartphone uses somewhere between 500 and 900 MLCCs, a 5G handset requires more than 1,0001.
The infrastructure side is adding further demand for these types of parts. 5G’s increased air-interface frequencies and technologies to support high data rates call for a greater number of smaller cells containing multi-input/multi-output (MIMO) base stations that utilize antenna diversity and beamforming. From the capacitor manufacturers’ perspective, ensuring component reliability will be a crucial requirement. Meeting the increase in volume demand will likely be more complex than the technical challenges.
Ceramic capacitors and alternatives
Different styles and types of MLCCs are needed to fulfil handset and infrastructure applications. In handsets, extreme size constraints could raise demand for SMD chip capacitors in extremely small form factors such as Yageo’s CC 01005 series. MLCCs are often regarded as general-purpose devices, although various dielectric chemistries are available such as NP0 class 1 devices typically chosen for frequency-control applications such as filters and oscillators.
Class 1 dielectrics are also chosen where stability over temperature is a key requirement. Class 2 dielectrics like X7R and X5R provide the greatest volumetric efficiency. Class 2 devices in the CC 01005 series provide capacitance values up to 470 nF for space-constrained decoupling and coupling applications.
Occasionally, technologies like KO-CAP may be considered depending on circuit conditions and design constraints. Kemet’s KO-CAP polymer-tantalum capacitor families can be used in certain circuits (Fig. 1). If the total capacitance required is less than about 680 nF and the voltage rating is less than 50 V, engineers can use them. The advantage is that fewer individual KO-CAPs are needed to achieve the same overall capacitance and voltage rating, reducing the total number of components required in comparison to MLCCs.
Fig. 1: Flow chart showing the decision tree for utilizing KO-CAP in a design (Image: Kemet)
As far as the technical development of capacitors is concerned, manufacturers need to be ready to deliver products with a suitable blend of properties to meet system performance demands at the right time. Efficiency is an underlying concern in both RF and power-conversion circuits, and capacitor selection can strongly influence the achieved result.
The 5G world is moving towards higher operating frequencies. Initial deployments will focus on frequency range 1 (FR1), which, although below 6 GHz, represents an increase over the frequencies used in preceding networks. Current RF-capacitor technologies are typically ceramic capacitors with base-metal electrode systems, which have high Q, thereby ensuring low losses. Kemet has already developed Ultra HiQ-CBR capacitors with C0G dielectric for RF and microwave applications, including unique variants with low equivalent series resistance (ESR), which can comfortably handle 5G frequencies.
On the other hand, there is always pressure on manufacturers to offer new devices with increased volumetric efficiency, expressed as CV; capacitance multiplied by voltage. While there are familiar techniques for achieving greater capacitance within the same or smaller case size, miniaturization can bring disadvantages such as reduced ripple current handling capability and lower resilience to electrostatic discharge (ESD).
Among the most exciting features of 5G are massive machine-type communications (mMTC) and ultra-reliable low-latency communication (URLLC). These features enable new M2M use cases such as time-critical industrial IoT (IIoT) applications, autonomous vehicles and drones, and asset tracking.
Although some of the new M2M use cases will require more comprehensive coverage, which 5G networks will not offer for some time. Private 5G networks could be quickly rolled out to cover individual factories or industrial campuses. These networks may significantly influence future capacitor development, demanding greater ruggedness and temperature capability, increased volumetric efficiency and stability, and reduced losses.
The next generations of industrial automation and robotics could at the very least raise demand for rugged MLCC technologies. One example is the soft terminations Yageo has developed to ensure its CS series MLCCs can allow the board to flex by more than 3 mm without excessive stress on the capacitor. Kemet has addressed the reliability and safety challenges presented by board flexing with flexible termination technology in FT-CAP devices and fail-open MLCCs such as the FO-CAP and fail-safe floating-electrode FE-CAP series.
We expect more opportunities for new high-performing and specialty components to meet the needs of these new applications. At the same time, robustness and reliability in these components must be assured in harsh environmental conditions. While the GSMA standards groups have engineered features to ensure reliable data exchanges into the 5G air interface, next-generation connected industrial equipment must be able to stand up to life on the factory floor or the road.
Fig 2: CT scan showing shock groove to prevent radial movement. (Image: Kemet)
The automotive industry’s demands have encouraged the emergence of extremely robust construction techniques, such as Kemet’s high-vibration electrolytic capacitors that introduced new design features such as the anti-vibration grooved case that enhances axial and radial fixation of the foil/electrolyte winding (Fig. 2).
Higher temperature ratings are another critical development driven by both the industrial and automotive sectors. Automotive, commercial, and industrial-grade high-temperature ceramic capacitors are available for operation up to 150°C and 260°C in SMD and THT technologies, respectively, utilizing known and proven dielectric technologies such as C0G and X7R that provide thermal stability, minimal capacitance decay with time, low piezoelectric noise, and low ESR and ESL.
As 5G networks roll out and the extent of the services that will emerge becomes clearer, application developers and solution providers can take advantage of exciting opportunities. In particular, the vast diversity of devices expected to connect to these networks will challenge component manufacturers on every level, from raising component performance and delivering new technical innovations to ensuring proper management of the supply chain.
About the author
Hue Thu Duong graduated in 2019 with her undergraduate degree in Electrical Engineering from California Polytechnic State University (Cal Poly), San Luis Obispo. Hue Thu joined Kemet’s Americas FAE team shortly after graduating from Cal Poly. She has been with Kemet for two years now and is constantly learning about industry applications and trends. She is passionate to learn and understand the needs of the industry and offer customers solutions.
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