The STP5NK50ZFP: The TO-220FP full-pack package has an isolated tab — no insulating pad or washer needed between the metal back and the heatsink.
STMicroelectronics lists the STP5NK50ZFP as NRND (Not Recommended for New Design). No last-time-buy date is published in the current record. For an existing production BOM, the NRND status means you have time to qualify a replacement, but you should not start a new design with this order code.
The TO-220FP package dissipates up to 70 W at the case, but the isolated tab means the thermal resistance from junction to case is higher than a standard TO-220 — account for that when sizing the heatsink at high ambient temperatures.