ISSUE 012 Winter 2021 Sigma Powertrain EMAX transmission dossier l In conversation: David Hudson l 48 V systems focus l 2021 Battery Show North America and Cenex-LCV reports l Everrati Porsche 911 digest l Switching insight l Motor laminations focus

sintering with Argomax silver sinter paste. The paste has specially designed silver particles to work with low-pressure sinter dies and the STPak package materials. The Argomax paste creates a strong attachment through silver metallic bonds to directly bonded copper substrates, providing high levels of electrical conductivity and good thermal properties. This improves long-term reliability, and reduces the direct conductive losses and inductive losses by placing the STPak transistors closer together and reducing the number of discrete devices required. This has led to a 93% efficiency in inverter designs, which adds 10% to the range, said Edoardo Merli, group vice-president of STMicroelectronics’ Automotive and Discrete Group. High-power aeromotor in testing Wright Electric is testing a 2 MW motor for electric aircraft (writes Nick Flaherty). According to Jeff Engler, the company’s CEO, it has twice the power of other motors in testing. It will be a key building block for large electric aircraft with more than 100 seats, and follows development contracts from NASA, the US Department of Energy, the US Air Force and the US Army. The motor has a specific power of 10 kW/kg, and is designed to be scalable from 500 kW to 4 MW for different applications. Ten motors would work with custom inverters in an array for passenger aircraft with more than 150 seats, or in smaller, 50-passenger turboprop aircraft such as the ATR-42 in a two- motor array format. The inverter has an efficiency of 99.5%, and operates at 300 kHz and over 1000 V. This higher voltage requires improved insulation and a sophisticated thermal management design, said Engler. The motor will now proceed to the next phase of development, which will include integrating it with an in- house developed efficient inverter, high-altitude chamber testing, and qualification for flight readiness over the next 2 years. Wright Electric is also retrofitting a 100-seat Bae 146 aircraft with the motor and inverter, along with a hydrogen fuel cell or aluminium-air battery as the power source. The company intends to fly the aircraft, which it calls Spirit, in 2026. The motor is designed to be scalable from 500 kW to 4 MW Improved sintering enables the STPak inverter package to be mounted directly onto heat sinks Inverter sintering set to boost range MacDermid Alpha Electronics Solutions is working with STMicroelectronics on improved sinter technology for EV inverter assemblies. The process, known as pressure sintering, can significantly increase vehicle efficiency and range as well as lowering production costs (writes Nick Flaherty). Pressure sintering provides much lower thermal resistance in an inverter, which leads to better power cycling and mechanical reliability over conventional techniques. The biggest contributors to the overall thermal resistance (R th ) from the die to the heat sink are the interconnecting materials, including the thermal interface material (TIM), which can account for more than half the total thermal losses. By replacing the TIM or solder with a thinner, highly conductive pressure sinter layer, the R th falls by 10-15%. This also improves reliability by managing the stress and warpage between the package and heat sink, as the pressure sintering can be achieved at a lower temperature than other approaches. This allows STMicroelectronics’ STPak package for automotive traction inverters to be mounted directly onto the inverter heat sinks using pressure MOTORS MATERIALS 6 Winter 2021 | E-Mobility Engineering The Grid