190 mOhm at 8.5 A — conduction loss anchor
The STB24N60M6 is an N-channel 600 V MOSFET from ST's MDmesh™ M6 series, in a D2PAK (TO-263) surface-mount package.
Rds(on) is specified at 190 mOhm max with Vgs = 10 V, Id = 8.5 A, at 25 °C junction. That same on-resistance rises with temperature — expect roughly 1.6× at 125 °C junction, a factor to budget into the thermal loop. The 23 nC gate charge is low for a 600 V, 17 A die; it keeps the switching transition short, which reduces turn-on and turn-off losses in hard-switched topologies. Input capacitance Ciss is 960 pF at 100 V drain — a figure that helps estimate the driver's peak current requirement.
The D2PAK (TO-263) is a surface-mount package with a large exposed tab on the bottom. For rework, the tab's thermal mass means a preheat plate or bottom-side heater is almost mandatory; a hot-air nozzle alone will struggle to get the solder paste under the tab fully liquid without scorching the board. Orientation is marked by a chamfer on the package body.