Patent ID: 7903421

Claim:
A locking device for securing a heat sink to a printed circuit board, the locking device comprising: a shaft having a plurality of outer teeth protruding outwardly from an outer surface of a top end thereof, and a clamping portion disposed at a bottom end thereof, the outer teeth being arranged one by one along an axial direction of the shaft; a knob having an inner tooth protruding inwardly from an inner surface thereof, the knob being mounted around the top end of the shaft, the inner tooth meshing with a selective one of the outer teeth of the shaft; and an elastic member coiled around the shaft and located under the knob; wherein a length of the elastic member changes when the inner tooth of the knob meshes with another one of the outer teeth of the shaft different from the selective one of the outer teeth after the knob has been moved along the axial direction of the shaft for thereby adjusting a pressure of the locking device on the heat sink.