Heat sink and method of manufacturing the same

A heat sink includes a base with a plurality of recesses defined therein, a plurality of columned fins each having a head and a body extending from the head, and a cover joining with the base. Each head is received in and higher than a corresponding recess of the base. The heads are sandwiched between the cover and the base, whereby the columned fins are secured on the base. A portion of the cover contacting the head of each of the columned fins protrudes to form a deformed part. A method of manufacturing the heat sink is also disclosed.

BACKGROUND

1. Technical Field

The present disclosure relates generally to a heat sink, and more particularly to a heat sink having a base and a cover securing heads of columned fins therebetween.

2. Description of Related Art

Generally, in order to ensure the normal running of an electronic device, a heat sink is used to dissipate heat generated by the electronic device. A conventional heat sink includes a base and a plurality of fins integrally extending from the base. However, lengths of the fins are limited by a material performance. Thus, a surface area of the fins is restricted, which impacts heat dissipation effect of the heat sink. For increasing the surface area of the fins, the base and the fins are separated first and then combined by solder or other means. Nevertheless, a cost of manufacturing the heat sink increases.

What is need therefore is a heat sink having a good heat dissipating capability and convenient and easy to manufacture.

DETAILED DESCRIPTION

FIG. 1andFIG. 2illustrate a heat sink in accordance with a first embodiment of the present disclosure. The heat sink dissipates heat from a heat-generating component such as a CPU (not shown). The heat sink comprises a base10, a cover20mounted on a top of the base10, a plurality of columned fins30arranged on the base10and secured by the cover20, and a plurality of plate fins40engaged on the columned fins30. Each of the base10, the cover20, and the columned and plate fins30,40is made of material having good heat conductivity, such as aluminum or copper.

Also referring toFIG. 3, a bottom of the base10is for contacting the heat-generating component. A plurality of circular recesses11are defined in the top of the base10; in this embodiment, the recesses11are blind holes. The recesses11are arranged in several lines in accordance with the present embodiment; of course the recesses11can be arranged in other forms in accordance with alternative embodiments. Two studs12protrude from two diagonal corners of the base10. The studs12are integrally formed on the base10by punching. Thus, a concave (not labeled) is defined in the bottom of the base10corresponding to each stud12.

The cover20is a thin plate and a thickness thereof is about a quarter of that of the base10. A plurality of holes21is defined in the cover20corresponding to the recesses11of the base10. A diameter of each hole21is slightly smaller than that of each recess11. Two orifices22are defined in two diagonal corners of the cover20, corresponding to the studs12of the base10.

Each columned fin30comprises a head31and a body32extending therefrom. Understandably the columned fins30can be square, prism or other shape in alternative embodiments, when the shapes of the recesses11and the holes21are changed accordingly. Left columned fins30are higher than right columned fins30, which render tops of columned fins30to be at different levels. The head31is bigger than the body32; that is to say, the head31has a diameter larger than that of the body32, and the columned fin30has a T-shaped profile in longitudinal section. The head31is received in the recess11of the base10. The head31is slightly higher than the recess11; that is to say that the head31has a thickness larger than a depth of the recess11. Preferably, the head31is 0.05-0.15 mm higher than the recess11. Thus, a top end of the head31is extended out of the recess11. The body32is slightly smaller than the hole21of the cover20, and the head31is bigger than the hole21; the hole21has a diameter larger than that of the body32, but smaller than that of the head31, whereby the body32can be inserted through the hole21of the cover20, and the cover20can mount on the top end of the head31to secure the head31between the base10and the cover20.

The plate fins40are parallel to each other. A plurality of holes42are defined in the plate fins40to allow the bodies32of the columned fins30to extend therethrough and thereby securing the plate fins40on the bodies32of the columned fins30.

In assembly, the cover20is brought to move downwardly through the bodies32of the columned fins30until the cover20reaches the heads31. The plate fins40are interferentially engaged with the bodies32of the columned fins30and secured thereon. The heads31of the columned fins30are received in the recesses11of the base10. The cover20is pressed toward the base10to thereby force the studs12of the base10to rivet into the orifices22of the cover20, and intimately joint the base10and the cover20together. The columned fins30are thus secured on the base10by the joint of the bottom and covers10,20. Since the head31is higher than the recess11, a portion of the cover20contacting the top end of the head31at a periphery of the hole21protrudes upwardly to form a substantially annular deformed part23during the pressing of the cover10toward the base20.

The columned fins30are secured more tightly by the cover20due to the protrusion of the top ends of the heads31out of the recesses11.

A heat conducting grease can be filled between the heads31of the columned fins30and the recesses11of the base10to reduce heat resistance therebetween.

FIGS. 4-7illustrate a heat sink in accordance with a second embodiment of the present disclosure. The heat sink comprises a base10a, a cover20amounted on a bottom of the base10a, a plurality of columned fins30asecured between the base10aand the cover20a, and a plurality of plate fins40aengaged on the columned fins30a.

A plurality of through holes extend through the base10a; each through hole has a circular recess11adefined in a bottom of the base10aand a circular passage13adefined in a top of the base10aand communicating with the recess11a. The passage13ais smaller than the recess11a. The recess13ais 0.05-0.15 mm shorter than the head31aof the columned fin30a. The base10ais configured that the bodies32aof the columned fins30acan pass through the passages13afrom the bottom thereof and the heads31aare received in the recesses11awith bottom ends thereof protruding out of the recesses11. Two orifices12aare defined in two diagonal corners of the base10a.

The cover20ais a thin plate and a thickness thereof is about a quarter of that of the base10a. Two orifices22aare defined in the cover20acorresponding to the orifices12aof the base10a. A bottom of the cover20ais for contacting the heat-generating component to dissipate heat.

In assembly, the bodies32apenetrate through the passages13afrom the bottom of the base10a, and the heads31aare received in the recesses11aof the base10a. The cover20ais attached to the bottom of the base10a, and the cover20aand the base10aare jointed together by inserting rivets50into the orifices12a,22aof the base10aand cover20aand pressing the cover20aand the rivets50from a bottom of the cover20aupwardly toward the base10a. The columned fins30aare thus secured by the base10aand cover20awith heads31athereof sandwiched between the base10aand cover20a. Since the head31ais higher than the recess11a, a portion of the cover20acontacting the bottom end of the head31aof each columned fin30aprotrudes downwardly to form a deformed part23aduring the pressing. The plate fins40aare pressed to interferentially engage with the bodies32aof the columned fins30a. At last, the deformed part23ais machined to be flat with other portions of the bottom of the cover20aas shown inFIG. 7, to avoid an interference of the heat-generating component contacting the bottom of the cover20a.

It is understood that certain assembly steps previously described may be removed, while others may be added, and the sequence of steps may also be altered. For example, after the bodies32penetrated through the passages13aof the base10a, and the heads31aof the columned fins30aare received in the recesses11aof the base10a, the plate fins40acan be interferentially engaged with the bodies32aat first, and then the cover20ais pressed toward the base10ato join with the base10a.