Automotive MLCCs Balancing Reliability with Miniaturization and High Capacitance in a Closely Intertwined Evolution with the CASE Trend (2/3)
In Part 1 of our three-part series, we presented the role played by the automotive multilayer ceramic capacitors (MLCCs) from Murata Manufacturing (hereinafter, “Murata”) in the major transformation being undertaken by the automobile industry. Murata is a global leader of technology development in this field as the top manufacturer with a dominant market share of 50%. The direction of that technology and product development will influence the deployment of automotive applications in the near future. Part 2 of our series will introduce the technologies and production systems that support the strengths of Murata’s automotive MLCCs. In addition, we also heard more about the direction of automotive MLCC development due to the progress of the Connected (C) and Autonomous (A) features that are part of the four elements that make up the CASE trend.
Utilizing the strengths of integrated manufacturing to fabricate on-board quality from the materials
--In order to develop the MLCCs required for automobiles, what types of technology development is Murata concentrating on?
As we have discussed so far, automotive applications require a wide range of products from high capacitance products for high-performance processors with a low voltage drive to support autonomous driving inside the vehicle to high-voltage-tolerance products for battery control and noise suppression in electric vehicles. Generally speaking, Murata is undertaking the development of two technologies as basic technologies to support these diverse product families (Figure 1).
The first basic technology is material design technology, which considers the usage environment (environmental temperature and applied voltage) within the vehicle to achieve characteristics and levels of reliability according to the intended application. At Murata, we use integrated manufacturing from the materials to the devices. We utilize that strength to fabricate on-board quality from the ceramic powder manufacturing stage. Specifically, we are pursuing the ultrafine atomization of the materials that form the ceramics and electrodes (upper photo in Figure 5) and the uniformity of their variation and dispersion (lower photo in Figure 5).
The other basic technology consists of a ceramic processing and molding technology to suppress variations in order to meet on-board quality requirements. While advancing thinner electrodes and dielectric layers (middle photo in Figure 5), we are developing technologies to mold, laminate, and perform calcination processing, etc. on slurry*1 sheets to achieve high-capacitance and high-voltage-tolerance characteristics. Such production processes are integrating with the materials development while developing optimal processes. Building in quality during the development stage utilizing a system of integrated manufacturing that other companies lack ensures on-board quality while expanding the product range and becomes the source of the increasing competitiveness of Murata’s MLCCs.
*1 Slurry refers to a muddy mixture that combines minerals, etc. within a liquid. In the manufacturing of MLCCs, fine particles of dielectric ceramics are mixed with a liquid binder (connector) to create a slurry that is stretched into a thin sheet to form a slurry sheet (also called a “green sheet”). The sheet is then thinly coated with an electrode paste, laminated, and sintered to create an MLCC.
--We believe that in order to fabricate MLCCs that reflect the needs of the market from the material level, it is necessary to conceptualize the product specifications that are required by the market from a considerably early stage.
That’s right. When developing products at Murata, we painstakingly engage in activities to draw a clear roadmap that starts from the market trends. First, we draw a needs roadmap from the market roadmap that captures the needs of the capacitor market and apply that to the product roadmap. Through such activities, we envision what products should be introduced to the market at what time and how many years into the future we should continue to supply them.
In addition, together with the Materials Department and the Production Engineering Department, we create a technology roadmap that considers changes in applications and circuit technologies to promote technology development with an awareness of advanced development that looks three to five years into the future for the Materials Department and from one to three years ahead for the Product Department. However, because we are promoting development while predicting the future, naturally we do miss the mark at times. To increase the accuracy of those predictions, we listen carefully to the opinions of customers with a focus on the Marketing Department and internally formulate a sufficient hypothesis while creating the roadmap.
Building a system that can provide a stable supply according to market requirements
--What kind of system is used to produce automotive MLCCs?
Automotive MLCCs are produced under a system that positions Izumo Murata Manufacturing Co., Ltd. located in Izumo City, Shimane Prefecture as the “mother factory” (Figure 2). Founded in 1983, the Izumo plant has been certified under the IATF16949 standard for quality management systems in the automotive industry. Regardless of whether the destination is domestic or overseas, cutting-edge products are produced here. In addition, the Philippines plant established in the outskirts of Manila in 2011 also handles mainly on-board components. This plant produces high-volume, generic products.
Systems that are capable of producing on-board components have also been established at Fukui Murata Manufacturing and Murata Electronics Singapore. From a business continuity planning (BCP) perspective, these plants are intended to act as a replacement in the event that Izumo Murata Manufacturing and the Philippines plant are unable to produce components to maintain a stable production system and fulfill our supply responsibilities. We are striving to have our customers authorize multiple plants so as to be able to optimize supply worldwide.
5G-compliant grade of automotive MLCCs required for "Connectivity"
--What types of needs exist for automotive MLCCs within each of the four elements that make up the CASE acronym? First, let’s start with “C,” which stands for “Connected.”
In order to more closely connect cars to the cloud and traffic infrastructure, the acceleration of wireless communications is advancing through the application of fifth-generation mobile communication systems (5G). As a result, it is expected that requirements to develop automobile grade versions of the advanced MLCCs that have been introduced in cutting-edge smartphones will emerge. For example, there are high-frequency MLCCs for antenna matching.
Moreover, if V2X*2 linked to ITS, etc. is realized through the introduction of 5G, applications linked to the powertrain system may appear that enable cars to detect traffic congestion ahead and automatically apply the brakes, etc. Therefore, MLCCs are required to robustly ensure safety through their reliability.
In order to satisfy such requirements, various types of component technologies and processing technologies have become necessary to achieve high quality and high reliability. At Murata, we offer many product lineups that contribute to the evolution of connectivity, such as capacitors with a high Q factor*3 for matching as well as capacitors for V2X communication modules. We are promoting the development of automotive-grade components based on the technologies for these applications.
*2 V2X (Vehicle to X) refers to communication that connects a vehicle with nearby people, other vehicles, and traffic infrastructure, etc.
*3 The Q factor (Quality Factor) is an indicator that represents how high the performance is for a capacitor.
--It is anticipated that various frequency bands will be used for 5G. Within the development of automotive MLCCs, what specification-based products are you considering?
We are mainly envisioning support for the “sub-6”*4 frequency band. The millimeter wave frequencies are too high and do not generate any demand for capacitors used in antenna-matching applications. The deep-rooted demand to miniaturize on-board communication systems is not limited to just 5G support but is also a requirement for 4G LTE, and many customers are seeking miniature, high-capacitance MLCCs with on-board quality. Customers dealing with communication modules frequently deploy consumer use components, so requests to provide the same miniature MLCCs as smartphones with on-board quality have arisen. We believe that it is Murata’s mission to respond to those requests.
*4 Sub-6 refers to a frequency band used by fifth-generation mobile communication systems that consists of a frequency band at 6 GHz or less, which was previously not used for 4G.
MLCCs for power supplies used in high-power-consumption automated driving systems
--Next, what can you tell us about the Autonomous aspects, which represent the “A” in the “CASE” acronym?
The evolution of car automation has been significant with previous systems mainly playing the role of providing driving support to drivers. However, future systems will be in charge of driving and will detect the road conditions and the status of the driving environment to make the appropriate decisions while operating the car. In order to realize such advanced automated driving features, a large volume of data collected from many different types of sensors deployed throughout the car must be processed. It is expected that the high-performance CPUs and FPGAs used to process such data will consume more power than the ECUs utilized in cars up to now.
It is likely that high-capacitance MLCCs will be used to supply the electrical charge needed to properly drive control ICs in power supply circuits used to control power supply systems that supply large amounts of power to the computers (Figure 3). As the amount of current consumed by CPUs, etc. increases, the capacitance and the number of components used increases for MLCCs used in power supply circuits. In addition, to increase safety there is also a tendency to build redundant power supply circuits so that the automated driving features do not stop even if the power supply circuit fails, which is also a factor behind the increase in the number of components used.
Therefore, it is likely that the need for miniature and high-capacitance MLCCs as well as MLCCs with low inductance (low ESL*5) characteristics to reduce the number of MLCC components used around the periphery of control ICs will increase (Figure 4). Of course, the automated driving function is an important application for controlling the vehicle movement, so automotive-grade components with high reliability are essential.
*5 ESL refers to equivalent series inductance. The equivalent circuit model for a capacitor can be expressed as a series connection of the C, R, and L elements with the “L” called the “equivalent series inductance.”
--I would guess that self-driving cars are equipped with many sensors, but will a new need for MLCCs emerge around those sensors?
I think that circuits embedded within cameras and millimeter-wave radars will use a similar power supply design. Fundamentally, MLCCs are used in the accompanying power supply lines that drive the control ICs of these sensors. Miniaturization and high capacitance are required here as well.
The information presented in this article was current as of the date of publication. Please note that it may differ from the latest information.
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