[Pros] Strong mechanical attachment. Highest thermal interface material preload. Easy removal and installation. [Cons] Requires holes in the board which increases complexity of traces in PCB. [Cost] Moderate [Method] 
Push pin with compression springs
T h e r m a l t a p e
E p o x y
W i r e f o r m Z - c l i p s
C l i p - o n
P u s h p i n w i t h c o m p r e s s i o n s p r i n g s
S t a n d - o f f s w i t h c o m p r e s s i o n s p r i n g s