Mechanics and electronics
Power electronics is a mechatronics problem in an electrical costume.
Both sides
Mechanics and mechatronics at technical school, and a year at an instrument-maker’s bench before any of the electronics. Since 2016: magnetics design, thermal paths, shielding and mechanical integration on automotive high-voltage converters.
Why it matters
A converter that passes on the bench and fails in the product usually failed at packaging, tolerance stack, thermal path or volume fill. None of those appear on the schematic, so a team reading only the schematic looks in the wrong place for weeks.