GENİŞ BANT ARALIKLI SİLİSYUM KARBÜR TABANLI MOSFET ALT-MODÜL TASARIMI
Özet
Silicon carbide (SiC) based devices, which are an example of wide bandgap semiconductors, have several advantages over silicon (Si) based devices, such as operating at high temperatures, high thermal conductivity, and high breakdown voltage. With these superior features, more efficient and smaller systems in volume and weight are obtained. Thanks to these advantages of silicon carbide compounds, their usage is increasing in various fields such as electric vehicles, charging stations, renewable energy, and railway applications. SiC MOSFET module is formed through packaging processes of bare dies such as die bonding and wire bonding. The packaging technology plays a crucial role in determining the device's operating temperature, frequency, power losses and electromagnetic immunity to achieve full performance from silicon carbide. In this thesis study, sub-module design and simulation activities suitable for the module packaging structure have been completed. Subsequently, commercial off-the-shelf SiC MOSFET and SiC diode dies were obtained, and sub-module production was carried out. During sub-module production, a double-sided copper-coated Al2O3 ceramic substrate was utilized, and copper paths were created with a laser-engraving device. Then, the die bonding operation was performed. For the electrical connections between the die and the external interface, the wire bonding process was performed using 1 mil gold wire. The sub-module's operating voltage was increased by applying insulation (encapsulation) material. In addition, the current-voltage characteristics of the obtained sub-module were extracted, and tests such as leakage current test and Rds(on) resistance measurement were carried out for design verifications. The test data were obtained from the sub-module produced with the double pulse test circuit under 600V and 800V, and with different gate drive resistors. Using these data, switching times and switching losses were calculated, and graphs were plotted. As a result of the tests, at 20 Ω gate drive resistor, the total turn-on time (ton) was 132ns, the total turn-off time (toff) was 90ns, the turn-on loss (Eon) under 800V/20A was 636.3μJ, and the turn-out loss (Eoff) was 304.1μJ. At a 5 Ω gate drive resistor, the total turn-on time (ton) was calculated as 54ns, the total turn-off time (toff) was calculated as 59ns, the turn-on loss (Eon) under 800V/20A was 197.8μJ, and the turn-off loss (Eoff) was calculated as 190.8μJ. The measurement results obtained from the submodule were compared with the values in the datasheet of the C3M0075120J switch, which uses the same SiC MOSFET chip but is produced with a discrete package structure.
