Normal
There seem to be lots of slim blower fans designed for laptop cooling that are thin enough maybe like this. Im guessing these tend to come with their plastic enclosure, & not just as a bare fan, and that is the problem for you, wanting the bare fan. So you'd have to figure out how to cut the fan out of it's plastic enclosure, or alternately, keep the enclosure & design the heatsink around the shape of the fan enclosure and just incorporate the thing into the heatsink.