How MLCCs are Supporting Widespread Automotive Evolution

Author : Christian Merkel, Product Manager, Murata

08 April 2024

Figure 1: Miniaturised 4.3µF 0402 sized automotive MLCCs
Figure 1: Miniaturised 4.3µF 0402 sized automotive MLCCs

The personal transportation landscape is undergoing a transformative shift of monumental proportions. Alongside the movement away from internal combustion engine (ICE) models to electric vehicles (EVs), there is a concurrent trend in the automotive sector towards embracing enhanced connectivity, digitisation, autonomy and system intelligence. What have traditionally been mechanical based designs are now shifting to ones that are shaped around electronic devices.

With this ongoing shift comes a dramatic alteration in the parts which are vital to vehicle design. What were previously critical items, such as turbochargers, have become obsolete - being replaced by new electronic hardware that automotive engineering teams must comprehend and effectively implement to enhance their designs. To accommodate a wide range of functions, from infotainment to electric motor management, contemporary EVs require the integration of multiple distributed electronic control units (ECUs), all of which must be supported by an array of components.

For automotive OEMs, this has had a significant impact on their purchasing habits. In order to cater to the needs of modern EV production, these companies now require a significantly greater number of electronic devices, such as capacitors. They need suppliers who have the ability to consistently produce high-quality and innovative solutions that can effectively meet the rigours of harsh automotive environments.

Capacitors in automotive
Manufacturers of automotive capacitors are faced with the task of guaranteeing the quality and reliability of parts in what are very challenging situations. While a capacitor failing in a smartphone handset after a few years may be a minor annoyance, it can become a serious inconvenience or even a safety hazard in a vehicle with an expected operating lifetime spanning for 20 years. Consequently, it is of utmost importance for passive component makers to match the functional performance and charge storage density of cutting-edge consumer technology devices, while simultaneously preserving the same-size packages and guaranteeing the quality and reliability attributes that automotive usage demands. This requires constant materials research, process development and production consistency.

The scale of the industry also reinforces the importance of capacitor selection. In a modern ICE powered car, approximately 8,000 multilayer ceramic capacitors (MLCCs) are needed across a wide range of different systems. For some of the latest EVs, the usage surpasses 10,000 MLCCs - and this will continue to rise with the ongoing evolution of vehicle intelligence and functionality. Decisions made with regard to component selection will have major consequences in terms of the safety and performance of these vehicles.

Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability
Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability

Prominent manufacturers of capacitors have to continually assess the influence of automotive design trends on their products. Many of them are currently exploring integration as a means to reduce component count and enhance reliability. This includes integrating multiple passive parts or developing advanced multifunction circuits. Increasing the diversity of options available is another key area, but this comes with challenges - including needing to meet stringent quality standards, to align with the evolving requirements of the car industry. The adoption of silicon-carbide (SiC) or gallium-nitride (GaN) semiconductor devices in power control circuitry will also prompt the need for new passive components capable of supporting their distinctive properties.

Unique technical challenges
When it comes to connectivity, the automotive industry is planning wider usage of 5G mobile communication technology for both infotainment services and vehicle-to-anything (V2X) interaction. V2X enables vehicles to establish dialogues with various items in the environment around them - including traffic signals, pedestrian crossings, plus other vehicles. These will be crucial for gathering contextual information to accentuate the safety of autonomous driving, as well as increasing the effectiveness of smart city infrastructure (for managing traffic congestion, tolling, etc.).

Due to the significant role played by 5G connections, it is imperative for passive manufacturers to create automotive-grade variants of advanced smartphone components, particularly in relation to high-frequency MLCCs tailored for antenna matching. However, this is not the only area of the vehicle which will require such solutions. The challenge of deploying autonomous vehicle systems is that they must be incredibly reliable. Any data lost or corrupted due to the influence of stray electronic noise on the vehicle’s sensors and control systems could have disastrous consequences.

High-capacitance MLCCs will be required to help drive the power supply control circuits, as well as for decoupling purposes in the power circuitry itself. As power usage increases and car manufacturers mandate more redundancy in safety-critical installations, such as the power supplies for vehicle autonomy systems, demand for these parts will continue to rise. Additionally, this is expected to ramp up the need for automotive-grade miniature and high-capacitance MLCCs with low equivalent series inductance (ESL) values, in order to minimise the quantity of MLCC components required for power control ICs and increase system integration. 

Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability
Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability

Accentuating reliability
There are 2 further emerging trends which will also impact on automotive suppliers. Firstly, targeting the increasing cost of ownership and limited parking in urban environments, is the growing number of city car clubs. Shared vehicles will require component makers to attain even higher reliability standards, due to their increased usage. This could indicate that manufacturers need to adopt more cautious designs, in order to meet the necessary reliability expectations.

Equally, following behind the consumer market, strong uptake of commercial EVs is now being seen. Similar to shared passenger vehicles, these delivery vans, buses and heavy goods trucks will have extended daily working schedules and need to endure rigorous conditions - potentially involving higher voltages and power loads. In order to meet the demands of customers seeking assured reliability, compact sizes and heightened capacitances, component manufacturers must invest in the development of new technologies.

Another noteworthy change, as seen from the standpoint of a component supplier, is the shift in the operating voltage of automobiles’ electrical systems. For several decades, a vehicle’s low-voltage system has been 12V, but now there is a push to move this to 48V. Similarly, a transition from 400V to 800V is underway on the high-voltage side - in pursuit of greater efficiency. Heightened operating voltages offer clear benefits, such as accelerated charging times and reduced wiring loom expense. The task for component makers lies in developing parts that can withstand these high voltages, while also meeting the latest safety standards that the industry demands, plus still maintaining the same level of quality and reliability that the automotive industry expects for lower voltages.

Addressing industry expectations 
Murata is actively advancing component and processing technologies to offer high-quality capacitors for modern automotive applications. For instance, it already provides capacitors with high Q factors for matching applications, as well as solutions for use in V2X communication modules. This capacitor maker concentrates on 2 primary methods to enhance its parts. There’s firstly a focus on developing ways to atomise the materials used to form the dielectric material and the electrodes of its MLCCs. Secondly, there is the goal of improving these components’ overall uniformity and dispersion, in order to comply with automotive quality standards. This involves the development of new materials and the investigation of new moulding, laminating and processing techniques, so as to ultimately produce parts with high capacitances and strong voltage tolerances. 

Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability
Figure 2: Technologies utilised in producing MLCCs with high capacitance and reliability

The automotive market poses an added challenge for passive component makers, as car companies have very high expectations of their suppliers. These expectations include meeting proprietary protocols, certifying factories to external standards, enabling independent plant qualification by customers, plus committing to significantly longer product lifetimes. Meeting these demands requires substantial production capacity, along with considerable engineering effort.

Vehicle electrification is already changing the automotive industry at an incredible rate, but alongside other initiatives (such as increasing intelligence and digitisation, plus raising system voltages), this is only going to be further amplified in the years ahead. While progress is absolutely necessary, it creates a number of challenges - not just for the industry but its supporting suppliers too. If the passenger EV market is to continue its exceptional rate of expansion, it requires innovative and reliable solutions from everyone involved - ranging from large assembly suppliers down to miniaturised passive component manufacturers. Continued advancement, even of the smallest parts, helps to drive the attractiveness of vehicles to consumers, as well as expanding new opportunities for more demanding markets, such as car sharing and commercial EVs. 

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