InterviewFeatured in ELEKTRONIK PRAXIS
Nov 5th, 2024
ROHM’s Power Semiconductor Strategy “Winning with SiC”
*The content and speaker titles are accurate as of the time of the interview (November 2024)
ROHM was the first in the industry to bring SiC power MOSFETs to the market. Now, we’re intensifying our efforts to secure the top position in the SiC power semiconductor market. We spoke with Tsuguki Noma, Corporate Officer and Director of the Power Device Business Unit, to discuss the strategies that will be employed to navigate the intensely competitive landscape.
---------- How will ROHM thrive amidst the fierce competition surrounding SiC power semiconductors?
---------- Can ROHM succeed in the EV traction inverter market?
Noma:
Of course! That’s been our goal, and I believe everyone at ROHM is committed to achieving it. However, there is no magic wand that guarantees success. We must overcome several challenges, chief among these being how effectively we can meet user needs. This is key.
ROHM has advanced its SiC power semiconductor technology, introducing several products that were the first to be mass produced globally. For example, our 4th Gen SiC power MOSFETs set a new industry standard for the lowest ON resistance at the time of their release. However, despite this, our market share is currently 5th, indicating means that there are challenges to address. In a rapidly growing market, speed is of the essence. Right now, sales are directly tied to production capacity, so we are urgently ramping up our production capabilities to boost sales.
At the same time, our relationship with customers, particularly automakers, is of utmost importance. The automotive industry has the broadest base among manufacturing sectors, making it critically important for Japan. Just as automotive companies differentiated themselves through internal combustion engines, in this era of vehicle electrification, often referred to as a once-in-a-century turning point, the battery and inverter will play a decisive role. This makes the power semiconductors that go into inverters crucial components. As a result, automakers are directly reaching out to Tier II and Tier III semiconductor manufacturers like ROHM to establish strategic partnerships. As far as what has been publicly announced at this point, we are advancing collaborations with Mazda Motor Corp. and China's Geely Automobile (Zhejiang Geely Holding Group), signaling significant developments in this context.
---------- What advantages do users gain from adopting SiC power semiconductors?
Noma:
It’s about enhancing electric efficiency to match the fuel consumption of gas-powered vehicles. Replacing Si power semiconductors with SiC can improve power costs by 5-10%, which is undoubtedly a major benefit. As the electric efficiency of EVs increases, the battery’s energy capacity can be reduced accordingly. Given the high cost of batteries, this translates to lower system costs, offsetting the higher price of SiC power MOSFETs compared to silicon IGBTs.
---------- Won’t replacing Si power semiconductors with SiC make the design process more challenging for users?
Noma:
Indeed, there are many cases where people struggle with mastering SiC power semiconductors. While SiC power MOSFETs offer the significant advantage of reducing both conduction and switching losses, the issue of unstable switching waveforms can arise. Therefore, we are focusing our efforts on providing support to help customers effectively utilize SiC power MOSFETs.
ROHM’s in-house analog semiconductor division develops and manufactures isolated gate driver ICs that, when combined with our SiC power MOSFETs, allow customers to maximize performance. We believe that one of ROHM’s key strengths is the ability to offer SiC power MOSFETs and isolated gate driver ICs as an integrated solution.
---------- What does it mean when SiC power MOSFETs become unstable?
Noma:
Designing power circuits with SiC power MOSFETs is inherently more complex due to the need to use multiple devices in parallel. A three-phase inverter, for example, utilizes six switches, each comprised of several SiC power MOSFETs connected in parallel. Such configurations can cause interference between MOSFETs, leading to unintended ON/OFF switching and potential failure or breakdown. To prevent signal waveform instability, it is necessary to provide support and collaborate closely with customers during the design process.
---------- How do SiC and GaN power semiconductors differ?
Noma:
The choice between SiC and GaN power semiconductors ultimately depends on the customer. However, there are certainly markets where adopting GaN power semiconductors is advantageous.
In EV applications, onboard chargers are sure to benefit from the higher switching speeds of GaN power semiconductors. But it is unlikely that GaN power semiconductors will see widespread use in traction inverters, the primary market for SiC, due to their relatively low switching frequency that maxes out at around 20kHz. The appeal of GaN power semiconductors lies in their ability to operate at much higher frequencies with minimal losses. On the other hand, onboard chargers could become a competitive arena for both SiC and GaN power semiconductors.
---------- In November 2023, ROHM announced the acquisition of Solar Frontier’s solar cell factory in Kunitomi Town, Miyazaki Prefecture, to be developed and operated it as the second Miyazaki Plant, with plans to begin operation in 2024 as the primary factory for SiC power semiconductors. What is the main purpose of acquiring this additional factory?
Noma:
The primary goal is to expedite the increase in production capacity. By acquiring this facility, we can supply products about two years sooner than if we were to build a new factory. Furthermore, having a large facility (factory) ready in advance allows us to adjust the amount of capital investment according to demand.
While only SiC power semiconductors were produced domestically in Japan, Miyazaki Plant No. 2 will also begin manufacturing SiC wafers. Our objective is to eventually make it the leading SiC power semiconductor factory in the industry.
Noma:
Until now, the application of SiC power semiconductors has been limited to specific industrial equipment like solar power systems and server power supplies. However, one area where the demand is rapidly increasing is traction inverters for electric vehicles (EVs), where growth is expected to continue.
The SiC power semiconductor market, valued at around 100 billion yen annually between 2021 and 2022, is projected to exceed 1 trillion yen by 2028 or 2030. With an estimated 70% to 80% of this growth expected to come from EV traction inverters, the question becomes whether we can capture this segment. The answer to this will determine ROHM’s success in the SiC power semiconductor market.