Mounting assembly for heat sink

A method for attaching a heat sink to an electronic package on a circuit board, the circuit board defining a plurality of apertures therein;

• the method comprising:
• a) providing a back plate having a main body, a first post, and a second post having a fastening portion;
• b) providing a heat sink, the heat sink comprising a base and a plurality of fins extending from the base, the base defining a plurality of holes therein;
• c) providing a clip having a first leg defining a guiding hole and a locking means, and a second leg defining a fastening slot;
• d) placing the heat sink on the electronic package such that the holes thereof are aligned with the apertures, respectively;
• e) attaching the back plate to an underside of the circuit board, the first post and the second post of the back plate each sequentially inserting through the apertures of the circuit board and the holes of the heat sink;
• f) placing the clip over the heat sink and causing the first post of the back plate to be received in the guiding hole of the clip;
• g) moving the clip laterally until the first post is engaged with the locking means of the clip;
• and
• h) engaging a fastening member with the fastening portion of the second post thereby sandwiching the second leg therebetween.

A mounting assembly comprising:

• a printed circuit board defining a plurality of first through holes;
• an electronic package located on the printed circuit board;
• a heat sink seated upon the electronic package with a plurality of second through holes in alignment with the first through holes, respectively;
• a back plate located on an underside of the printed circuit board with a plurality of first and second positioning posts extending upwardly through the corresponding first and second through holes, respectively;
• a clip including a main portion pressing downwardly against the heat sink, said clip further including first and second sets of holes of which, the first set defines configurations allowing the first positioning posts to freely extend upwardly therethrough and to successively relatively move horizontally to be restrained from withdrawal, and the second set defines configurations allowing fasteners to extend therethrough to fasten to the corresponding second positioning posts, respectively, wherein said fasteners press against the clip to have the clip in a tension manner for tightly combining the heat sink the electronic package thereunder, and to prevent the clip from upwardly moving away from the heat sink.