SiC's Highlight Moment in Automotive Application, Traction Inverter Becomes the Main Battlefield

Power semiconductors with silicon carbide (SiC) as their core are experiencing large-scale development in the wave of automobile electrification due to their superior performance.

In 2018, Tesla Model 3's main drive inverter replaced the traditional silicon-based IGBT with SiC MOSFET, bringing SiC to the center of the new energy vehicle stage. Since then, more and more automobile brands and semiconductor manufacturers have devoted themselves to the research and development and application of SiC devices. Today, although IGBT is still the mainstream of automotive inverters, its characteristics can no longer meet the new requirements of higher power density, lower power consumption, smaller size and weight, which has brought more advantageous SiC devices an opportunity to quickly increase in volume.

As the silicon carbide market becomes increasingly popular, the industry chain is also racing to expand, and the competition among players is becoming increasingly intense. Whoever can rely on technological innovation and differentiated services to bring more market-oriented products may be able to take the lead in this battle.

Main battlefield of automotive SiC: traction inverter

The rapid development of the new energy vehicle industry has fully magnified the range anxiety and also made SiC a highlight. Compared with traditional silicon (Si) materials, SiC has many advantages.

"From the perspective of physical properties, first of all, SiC has a wider bandgap, about three times that of Si, and a stronger breakdown field, about 10 times that of Si. This makes SiC's voltage resistance better, which is why we say that SiC materials can be used to make high-voltage products. Secondly, SiC's electron saturation speed is higher, so the switching speed is faster, which is why SiC is more energy-efficient and more compact. This is the characteristic of SiC materials, which determines that it can achieve higher voltage and higher frequency." Recently, at a media communication meeting on SiC power devices held by Rohm, a world-renowned semiconductor manufacturer, Mr. Tokuken Mizuhara from the System Solutions Development Headquarters at Rohm's Japan headquarters introduced.

In general, based on the advantages of material properties, SiC can be mainly used in high-power, high-voltage and high-frequency fields, which correspond to high-performance application tracks such as electric vehicles, industrial equipment and renewable energy systems, and these are precisely the tracks with great market potential at present.

Especially in the electric vehicle market, the penetration rate is continuously increasing. For example, in the Chinese market, according to the data from the China Automobile Association, the penetration rate of new energy vehicles in China has reached 36.74% from January to May. DC-DC, OBC, battery and drive unit (traction inverter, motor, etc.) are the main application areas of SiC power devices, and the resulting growth space of the SiC power device market is very strong.

According to data released by market research firm Yole Group, the SiC power device market is expected to reach $10 billion by 2029. In addition, wide bandgap technology is expected to account for more than 35% of the global power electronics market in 2029, of which silicon carbide accounts for 28.6%. With the application of silicon carbide in 800V electric vehicles, the automotive industry is expected to account for nearly 80% of the equipment market in the next five years.

According to Rohm's forecast, the potential market size of SiC is expected to exceed 200 billion yen (about 1.243 billion US dollars) by fiscal 2025 and reach 1 trillion yen (about 6.217 billion US dollars) in fiscal 2028.

Image source: ROHM

Mizuhara Tokuken emphasized that from the perspective of the market size of SiC power devices in automotive applications, the traction inverter has the largest market size. In other words, the main battlefield of the entire automotive SiC is the traction inverter. "If we further distinguish between diodes, discrete diodes, discrete transistors and full SiC modules in hybrid modules, we can see that full SiC modules account for the largest overall share."

With the rapid development of electric vehicles, the development of more efficient, smaller and lighter electric powertrain systems has been put on the agenda. However, on the other hand, SiC power modules, as key components, face the difficulty of reducing size and reducing losses at the same time. Therefore, "the market needs full SiC modules that support miniaturization and reduce working hours," said Mizuhara Dejian.

Rohm launches two-in-one SiC packaged module

Targeting this market, ROHM has recently launched a new product, the two-in-one SiC packaged module "TRCDRIVE pack™", for traction inverters for xEVs (electric vehicles) below 300kW.

According to reports, the module has a total of 4 products, including 2 750V models BSTxxxD08P4A1x4, and 2 1,200V models BSTxxxD12P4A1x1. ​​The TRCDRIVE pack™ series products have four major advantages, including miniaturization, high power density, reduced installation time, and mass production.

Image source: ROHM

Specifically, in terms of miniaturization, the product uses ROHM's proprietary structure to separate the main current and control signal, which greatly expands the heat dissipation area and achieves compact packaging. Compared with previous packaging technologies, the size of TRCDRIVEpack™ is reduced by 28%.

In terms of high power density, the 4th generation SiC MOSFET with low on-resistance is equipped, achieving 1.5 times the industry's ultra-high power density compared to ordinary SiC packaged modules.

In addition, the module top is equipped with a "press fit pin" pin, which eliminates the need for soldering circuit boards and effectively reduces installation time. At the same time, by maximizing the current path in the main current wiring and adopting a double-layer wiring structure, the inductance value (5.7nH) is reduced, which helps reduce losses during switching.

In terms of mass production, Mizuwon Deok-ken revealed that although this product is a module product, a mass production system similar to that of discrete products has been established. Compared with the previous ordinary SiC shell-type modules, the production capacity has increased by about 30 times.

Of course, in such an era of "involution", the launch of a single product can no longer adapt to the fierce market competition environment. To this end, Rohm also provides various support at the application and service levels. For example, to speed up the evaluation and application of TRCDRIVE pack™ products, Rohm also provides various support resources, including motor test equipment, rich solutions from simulation to thermal design, and two evaluation kits for double pulse testing and three-phase full bridge, so as to support evaluation under conditions close to actual circuit conditions.

TRCDRIVE pack™ three-phase full-bridge evaluation kit; Image source: ROHM

It is reported that the new TRCDRIVE pack™ product will be put into mass production in June 2024 with a monthly production capacity of 100,000 units.

It is worth mentioning that based on this series of products, Rohm also plans to develop a total of 12 silicon carbide module products with different package sizes and installation modes within 2024. In addition, Rohm is currently developing a six-in-one module with a heat sink, and will start supplying samples in the second quarter of 2024. Compared with the previous SiC shell type module, the power density will reach 1.3 times, which will further accelerate the design speed of traction inverters that meet the specifications and expand the product lineup.

Image source: ROHM

SiC market is highly competitive, and investment is underway

The continued expansion of the electric vehicle market has driven an increase in demand for power semiconductors. Today, vertical integration has become the dominant trend in the power silicon carbide ecosystem, with leading companies such as Rohm, STMicroelectronics, ON Semiconductor and Wolfspeed all having internal wafer growth capabilities in their supply chains.

As one of the world's leading semiconductor manufacturers and a major automotive power chip manufacturer, Rohm can provide a consistent production system from wafer production to manufacturing process, packaging and quality management methods. In recent years, it has shifted its business development focus to the field of silicon carbide power semiconductors.

According to information, Rohm currently has three silicon carbide-based power semiconductor production bases in Japan, namely the Apollo Chikugo Factory in Fukuoka Prefecture and the First and Second Factories in Miyazaki Prefecture. It is currently continuously expanding its semiconductor production capacity centered on silicon carbide power semiconductors.

In order to better develop the SiC business, in addition to the newly launched two-in-one SiC packaged module "TRCDRIVE pack™", Rohm also launched a new silicon carbide brand in the company's "Power Eco Family" - EcoSiC™.

"EcoSiC™ combines the terms 'Eco' and 'SiC', symbolizing the connection between ecosystem and excellent technology, and also highlighting ROHM's commitment to providing advanced and sustainable solutions." Mizuhara Tokuken said that in the future, in addition to the silicon carbide brand EcoSiC™ and the gallium nitride brand EcoGaN™ launched in 2022, ROHM will also add high-performance silicon products to the Eco series.

Image source: ROHM

According to Mizuhara Tokuken, facing the huge potential of the SiC market, Rohm's SiC business goal is to reach 110 billion yen (about US$760 million) by fiscal 2025 and 220 billion yen (about US$1.52 billion) by fiscal 2027. And by fiscal 2027, Rohm will achieve a sales target of over 60 billion yen (about US$413.7 million) for its SiC power module business.