Fastener and heat sink assembly having the same

A heat sink assembly adapted to dissipate heat generated by an electronic component mounted on a top face of a printed circuit board, the heat sink assembly comprising:

• a heat sink comprising a base disposed on the electronic component, the base defining a plurality of mounting holes;
• and
• a plurality of fasteners extending through the mounting holes of the heat sink, respectively, to assemble the heat sink to the printed circuit board, each of the plurality of fasteners comprising:
• a head,
• a post extending downwardly from a bottom face of the head and extending through the mounting hole of the heat sink;
• an elastic member encircling the post and compressed between the head and the base;
• and
• an engaging member fixed to the printed circuit board, a top of the engaging member engaging a bottom of the post;
• wherein when the post together with the head, is rotated relative to an axis thereof from a first position in which the bottom of the post and the engaging member are not locked with each other toward a second position, a torsion force will be produced by the engaging member to the post to thereby drive the post to lock with the engaging member.