Connecting element for heat dissipation unit and heat dissipation unit using same

A heat dissipation unit, comprising:

• a heat dissipation main body having an upper side, a lower side, at least four through holes, and a heat receiving zone;
• the through holes being located at four corners outside the heat receiving zone to extend from the upper side to the lower side of the heat dissipation main body;
• and the through holes respectively having a connecting element mounted therein;
• and
• the connecting element including:
• a screw having a screw head and a plurality of male thread provided at an upper and a lower end thereof, respectively, and the lower end of the screw with the male threads being extended through one corresponding through hole on the heat dissipation main body;
• a retaining ring being fitted on the screw at a position axially closely above the male threads after the latter is extended through the through hole, such that the retaining ring has one side abutted on the lower side of the heat dissipation main body;
• and a spring fitted on around the screw and having a top end and a bottom end;
• a sleeve having an upper end, a lower end, and a receiving space defined between and communicable with the upper and the lower end;
• the sleeve being provided near the upper end with a window radially communicable with the receiving space;
• and the screw and the spring fitted thereon being disposed in the receiving space, such that the lower end of the sleeve and the bottom end of the spring are pressed on the upper side of the heat dissipation main body;
• and
• a turnable retaining ring being fitted around the upper end of the sleeve and including an extension section downward extended from a lower rim thereof;
• a lower end of the extension section further sidewardly extended and curled toward a center of the turnable retaining ring to form at least one tongue;
• and the tongue being extended into the receiving space via the window of the sleeve to press on the top end of the spring, such that the spring is held in the sleeve in a compressed state.