Clamp TO-262 transistor against heatsink?
Is there any reason not use a TO-262 vertically mounted, clamped to a heatsink/enclosure?


Assuming you're not confusing TO-262 (aka I2PAK) with the much more common TO-263 (aka D2PAK or DDPAK), no there's no reason. In fact TO-262 is the vertical mount version, though-hole mount (unlike TO-263 which is surface), straight-leads.