Plane-type heat-dissipating structure with high heat-dissipating effect and method for manufacturing the same

Abstract

A plane-type heat-dissipating structure with high heat-dissipating effect includes a first heat-dissipating unit and a second heat-dissipating unit. The first heat-dissipating unit has an evacuated hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body. Work liquid is filled into the receiving spaces. The second heat-dissipating unit is integratedly formed on an outer surface of the first heat-dissipating unit.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plane-type heat-dissipating structure and a method for manufacturing the same, in particular, to a plane-type heat-dissipating structure with high heat-dissipating effect and a method for manufacturing the same.

2. Description of Related Art

Cooling or heat removal has been one of the major obstacles of the electronic industry. The heat dissipation increases with the scale of integration, the demand for higher performance, and the increase of multi-functional applications. The development of high performance heat transfer devices becomes one of the major development efforts of the industry. Heat pipes have excellent heat transfer performance due to their low thermal resistance, and are therefore an effective means for transfer or dissipation of heat from heat sources. Currently, heat pipes are widely used for removing heat from heat-generating components such as central processing units (CPUs) of computers.

A heat pipe is usually a vacuum casing containing therein a working medium, which is employed to carry, under phase transitions between liquid state and vapor state, thermal energy from an evaporator section to a condenser section of the heat pipe. Preferably, a wick structure is provided inside the heat pipe, lining an inner wall of the casing, for drawing the working medium back to the evaporator section after it is condensed at the condenser section. In operation, the evaporator section of the heat pipe is maintained in thermal contact with a heat-generating component. The working medium contained at the evaporator section absorbs heat generated by the heat-generating component and then turns into vapor and moves towards the condenser section where the vapor is condensed into condensate after releasing the heat into ambient environment. Due to the difference in capillary pressure which develops in the wick structure between the two sections, the condensate is then brought back by the wick structure to the evaporator section where it is again available for evaporation.

However, the design of the positions of the evaporator section and the condenser section still has improvement space.

SUMMARY OF THE INVENTION

In view of the aforementioned issues, the present invention provides a plane-type heat-dissipating structure with high heat-dissipating effect and a method for manufacturing the same. The present invention can achieve high heat-dissipating effect by matching two integrated heat-dissipating units. One of the two heat-dissipating units has an evacuated hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body. Work liquid is filled into the receiving spaces. The second heat-dissipating unit has a plurality of exposed heat-dissipating fins.

To achieve the above-mentioned objectives, the present invention provides a plane-type heat-dissipating structure with high heat-dissipating effect, including: a first heat-dissipating unit and a second heat-dissipating unit. The first heat-dissipating unit has an evacuated hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body. Work liquid is filled into the receiving spaces. The second heat-dissipating unit is integratedly formed on an outer surface of the first heat-dissipating unit.

To achieve the above-mentioned objectives, the present invention provides a method for manufacturing a plane-type heat-dissipating structure with high heat-dissipating effect, including: using an extruding mold to integratedly extrude a first heat-dissipating unit and a second heat-dissipating unit, wherein the first heat-dissipating unit has a hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body, and the second heat-dissipating unit is integratedly formed on an outer surface of the first heat-dissipating unit; closing one end of the first heat-dissipating unit; filling work liquid into the receiving spaces; and then extracting air from the receiving spaces and closing other opposite end of the first heat-dissipating unit to make the hollow heat-dissipating body become an evacuated hollow heat-dissipating body.

Therefore, the present invention has the following advantages:

1. The work liquid may generate capillarity by the design of the microstructures, so that the work liquid may flow back quickly to a heat-generating area to absorb heat. The microstructures can be any regular shapes (such as rectangular prism, a cylinder, a taper or a dovetailed shape) and any irregular shape according to different design requirement.

2. Each heat-dissipating fin has a rectangular prism, a cylinder, a taper or a dovetailed shape according to different design requirement.

3. The hollow heat-dissipating body provides the second surface, so that the heat-generating element is smoothly disposed on the second surface in order to increase heat-conducting efficiency. Hence, heat generated from the heat-generating element may be absorbed by the second surface, and the heat is dissipated by the heat-dissipating fins that are formed on the first surface.

4. A third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies of the third heat-dissipating unit and the dovetailed heat-dissipating fins of the second heat-dissipating unit.

5. A heat-generating element is retained on the second heat-dissipating unit by matching the dovetailed bottom seat of the heat-generating element and the dovetailed heat-dissipating fins of the second heat-dissipating unit.

In order to further understand the techniques, means and effects the present invention takes for achieving the prescribed objectives, the following detailed descriptions and appended drawings are hereby referred, such that, through which, the purposes, features and aspects of the present invention can be thoroughly and concretely appreciated; however, the appended drawings are merely provided for reference and illustration, without any intention to be used for limiting the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective, schematic view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the first embodiment of the present invention;

FIG. 1B is a partial enlarged view of the dotted line area in FIG. 1A;

FIG. 2 is a partial enlarged view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the second embodiment of the present invention;

FIG. 3 is a partial enlarged view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the third embodiment of the present invention;

FIG. 4 is a partial enlarged view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the fourth embodiment of the present invention;

FIG. 5 is a partial enlarged view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the fifth embodiment of the present invention;

FIG. 6 is a perspective, schematic view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the sixth embodiment of the present invention;

FIG. 7 is a perspective, schematic view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the seventh embodiment of the present invention;

FIG. 8 is a perspective, schematic view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the eighth embodiment of the present invention;

FIG. 9 is a perspective, schematic view of the plane-type heat-dissipating structure with high heat-dissipating effect according to the ninth embodiment of the present invention;

FIG. 10A is a flowchart of the method for manufacturing the plane-type heat-dissipating structure with high heat-dissipating effect according to the present invention;

FIG. 10B is a cross-sectional, schematic view of the extruding mold according to the present invention;

FIG. 10C is a partial, perspective, schematic view of the spindle of the extruding mold according to the present invention; and

FIG. 10D is a partial, enlarged view of the extruding mold according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B (FIG. 1B is an enlarged view of the dotted line range in FIG. 1A), the first embodiment of the present invention provides a plane-type heat-dissipating structure with high heat-dissipating effect, including: a first heat-dissipating unit 1a and a second heat-dissipating unit 2a.

The first heat-dissipating unit 1a has an evacuated hollow heat-dissipating body 10a (FIG. 1A shows central part of the hollow heat-dissipating body 10a), a plurality of supports 11a integratedly formed in the hollow heat-dissipating body 10a in order to divide an inner space of the hollow heat-dissipating body 10a into a plurality of receiving spaces 100a, and a plurality of microstructures 12a integratedly formed on an inner surface of the hollow heat-dissipating body 10a. In addition, the first heat-dissipating unit 1a can be made of aluminum alloy such as 1070 series, 6063 series or 6061 series etc. The first heat-dissipating unit 1a has a plurality of grooves 120a formed in the receiving spaces 100a, and each groove 120a is between every two adjacent microstructures 12a. In the first embodiment, each microstructure 12a has a rectangular prism and work liquid (not shown) is filled into the receiving spaces 100a.

Moreover, the second heat-dissipating unit 2a is integratedly formed on an outer surface of the first heat-dissipating unit 1a. The second heat-dissipating unit 2a can be made of aluminum alloy such as 1070 series, 6063 series or 6061 series etc. The second heat-dissipating unit 2a has a plurality of heat-dissipating fins 20a. In the first embodiment, each heat-dissipating fin 20a has a rectangular prism. However, the rectangular prism is just an example, and it does not limit the present invention. For example, each heat-dissipating fin 20a can be a cylinder, a taper, a dovetailed shape, or any shape in the present invention.

Therefore, the work liquid may generate capillarity by the design of the microstructures 12a, so that the work liquid may flow back quickly to a heat-generating area to absorb heat. In other words, when the plane-type heat-dissipating structure is evacuated, the work liquid would vapor quickly after absorbing heat generated by a heat-generating area. The heat absorbed by the work liquid (the vapor) may be dissipated (or cooling) by the first heat-dissipating unit and the second heat-dissipating unit, and at the same time the work liquid is cooling and flow back to the heat-generating area to absorb heat again by capillarity in order to achieve the circulation of heat absorption and heat extraction.

Referring to FIG. 2, the difference between the second embodiment and the first embodiment is that: in the second embodiment, each microstructure 12b has a cylinder.

Referring to FIG. 3, the difference between the third embodiment and the above-mentioned embodiments is that: in the third embodiment, each microstructure 12c has a taper.

Referring to FIG. 4, the difference between the fourth embodiment and the above-mentioned embodiments is that: in the fourth embodiment, each microstructure 12d has a dovetailed shape.

Referring to FIG. 5, the difference between the fifth embodiment and the above-mentioned embodiments is that: in the fifth embodiment, each microstructure 12e has an irregular shape.

However, the above-mentioned shape of each microstructure is just an example, and it does not limit the present invention. Any regular shapes such as rectangular prism, a cylinder, a taper or a dovetailed shape and any irregular shape are protected in the present invention.

Referring to FIG. 6, the difference between the sixth embodiment and the above-mentioned embodiments is that: in the sixth embodiment, the heat-dissipating fins 20f are integratedly disposed on one part (the first surface F1) of a top surface of the hollow heat-dissipating body 10f, and another part (the second surface F2) of the top surface of the hollow heat-dissipating body 10f provides a space for receiving at least one heat-generating element Hf. In other words, the hollow heat-dissipating body 10f provides the second surface F2, so that the heat-generating element Hf is smoothly disposed on the second surface F2 (heat-dissipating paste can be filled between the heat-generating element Hf and the second surface F2 extra) in order to increase heat-conducting efficiency. Hence, heat generated from the heat-generating element Hf may be absorbed by the second surface F2, and the heat is dissipated by the heat-dissipating fins 20f that are formed on the first surface F1.

Referring to FIG. 7, the difference between the seventh embodiment and the above-mentioned embodiments is that: the seventh embodiment further includes at least one third heat-dissipating unit 3g having a heat-dissipating body 30g, a plurality of heat-dissipating fins 31g extended upwards from the heat-dissipating body 30g, and a plurality of dovetailed retaining bodies 32g extended downwards from the heat-dissipating body 30g. The third heat-dissipating unit 3g is retained on the second heat-dissipating unit 2g by matching the dovetailed retaining bodies 32g and the dovetailed heat-dissipating fins 20g.

In addition, the second heat-dissipating unit 2g is integratedly disposed on one part (the first partial surface G1) of a top surface of the hollow heat-dissipating body 10g, and another part (the second partial surface G2) of the top surface of the hollow heat-dissipating body 10g is one end surface of the hollow heat-dissipating body 10g to provide a space for receiving at least one heat-generating element Hg, and the third heat-dissipating unit 3g is disposed over other end surface of the hollow heat-dissipating body 10g.

Referring to FIG. 8, the difference between the eighth embodiment and the above-mentioned embodiments is that: the eighth embodiment further includes at least one third heat-dissipating unit 3h having a heat-dissipating body 30h, a plurality of heat-dissipating fins 31h extended upwards from the heat-dissipating body 30h, and a plurality of dovetailed retaining bodies 32h extended downwards from the heat-dissipating body 30h. The third heat-dissipating unit 3h is retained on the second heat-dissipating unit 2h by matching the dovetailed retaining bodies 32h and the dovetailed heat-dissipating fins 20h.

In addition, the second heat-dissipating unit 2h is integratedly disposed on a top surface (the whole top surface H) of the hollow heat-dissipating body 10h, so that at least one heat-generating element Hh with a dovetailed bottom seat Bh is retained on one end surface of the second heat-dissipating unit 2h, and the third heat-dissipating unit 3h is retained on another opposite end surface of the second heat-dissipating unit 2h.

Referring to FIG. 9, the difference between the ninth embodiment and the above-mentioned embodiments is that: the ninth embodiment further includes at least two third heat-dissipating units 3i. Each third heat-dissipating unit 3i has a heat-dissipating body 30i, a plurality of heat-dissipating fins 31i extended upwards from the heat-dissipating body 30i, and a plurality of dovetailed retaining bodies 32i extended downwards from the heat-dissipating body 30i. Hence, the two third heat-dissipating units 3i are retained on the second heat-dissipating unit 2i by matching the dovetailed retaining bodies 32i and the dovetailed heat-dissipating fins 20i.

In addition, the second heat-dissipating unit 2i is integratedly disposed on one part (the first surface I1) of a top surface of the hollow heat-dissipating body 10i, and another part (the second surface I2) of the top surface of the hollow heat-dissipating body 10i is position on a central area of the first heat-dissipating unit 1i to provide a space for receiving at least one heat-generating element Hi, and the two third heat-dissipating units 3i are respectively disposed over two opposite end surfaces of the hollow heat-dissipating body 1i.

Referring to FIGS. 10A to 10D, the first embodiment is an example; the present invention provides a method for manufacturing a plane-type heat-dissipating structure with high heat-dissipating effect. The method includes the following steps:

Step S100 is that: using an extruding mold M to integratedly extrude a first heat-dissipating unit 1a and a second heat-dissipating unit 2a; wherein the first heat-dissipating unit 1a has a hollow heat-dissipating body 10a, a plurality of supports 11a integratedly formed in the hollow heat-dissipating body 10a in order to divide an inner space of the hollow heat-dissipating body 10a into a plurality of receiving spaces 100a, and a plurality of microstructures 12a integratedly formed on an inner surface of the hollow heat-dissipating body 10a, and the second heat-dissipating unit 2a is integratedly formed on an outer surface of the first heat-dissipating unit 1a.

Referring to FIG. 10B, the extruding mold M is composed of a mold body M1 and a spindle M2. The mold body M1 has a plurality of protrusion portions M10 disposed on an inner wall thereof, and the spindle M2 has a forming portion M20 extending forwards from one end thereof. In addition, the protrusion portions M10 can be used to extrude tooth shape, and the protrusion portions M10 are manufactured by contact fabrication or noncontact fabrication, for example, electro-chemistry (such as etching, electroforming, electro-discharge machining, and CNC wire cutting) and energy bundle processing (such as laser with different wavelength, electronic beam, and ultrasonic machining).

Referring to FIG. 10C, the forming portion M20 has a plurality of extending bodies M200 connected to the spindle M2 and extending forwards. There are many gaps G respectively formed between every two extending bodies M200. Each extending body M200 has a plurality of micro protrusions M2000 disposed on a top surface and a bottom surface thereof.

Referring to FIGS. 10B to 10D, the first heat-dissipating unit 1a and the second heat-dissipating unit 2a are integratedly extruded by matching the protrusion portions M10 of the mold body M1 and the micro protrusions M2000 of the forming portion M20.

Step S102 is that: closing one end of the first heat-dissipating unit 1a.

Step S104 is that: filling work liquid (not shown) into the receiving spaces 100a.

Step S106 is that: extracting air from the receiving spaces 100a and closing other opposite end of the first heat-dissipating unit 1a to make the hollow heat-dissipating body 10a become an evacuated hollow heat-dissipating body 10a.

In conclusion, the present invention has the following advantages:

1. The work liquid may generate capillarity by the design of the microstructures, so that the work liquid may flow back quickly to a heat-generating area to absorb heat. The microstructures can be any regular shapes (such as rectangular prism, a cylinder, a taper or a dovetailed shape) and any irregular shape according to different design requirement.

2. Each heat-dissipating fin has a rectangular prism, a cylinder, a taper or a dovetailed shape according to different design requirement.

3. The hollow heat-dissipating body provides the second surface, so that the heat-generating element is smoothly disposed on the second surface in order to increase heat-conducting efficiency. Hence, heat generated from the heat-generating element may be absorbed by the second surface, and the heat is dissipated by the heat-dissipating fins that are formed on the first surface.

4. The third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies of the third heat-dissipating unit and the dovetailed heat-dissipating fins of the second heat-dissipating unit.

5. The heat-generating element is retained on the second heat-dissipating unit by matching the dovetailed bottom seat of the heat-generating element and the dovetailed heat-dissipating fins of the second heat-dissipating unit.

The above-mentioned descriptions represent merely the preferred embodiment of the present invention, without any intention to limit the scope of the present invention thereto. Various equivalent changes, alternations or modifications based on the claims of present invention are all consequently viewed as being embraced by the scope of the present invention.

Claims

1. A plane-type heat-dissipating structure with high heat-dissipating effect, comprising:

a first heat-dissipating unit having an evacuated hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body, wherein work liquid is filled into the receiving spaces; and

a second heat-dissipating unit integratedly formed on an outer surface of the first heat-dissipating unit.

2. The plane-type heat-dissipating structure according to claim 1, wherein the first heat-dissipating unit and the second heat-dissipating unit are made of aluminum alloy.

3. The plane-type heat-dissipating structure according to claim 1, wherein the first heat-dissipating unit has a plurality of grooves formed in the receiving spaces, each groove is between every two adjacent microstructures, and each microstructure has a rectangular prism, a cylinder, a taper or a dovetailed shape.

4. The plane-type heat-dissipating structure according to claim 1, wherein the second heat-dissipating unit has a plurality of heat-dissipating fins.

5. The plane-type heat-dissipating structure according to claim 4, wherein the heat-dissipating fins are integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body provides a space for receiving at least one heat-generating element.

6. The plane-type heat-dissipating structure according to claim 4, wherein each heat-dissipating fin has a rectangular prism, a cylinder, a taper or a dovetailed shape.

7. The plane-type heat-dissipating structure according to claim 6, further comprising: at least one third heat-dissipating unit having a heat-dissipating body, a plurality of heat-dissipating fins extended upwards from the heat-dissipating body, and a plurality of dovetailed retaining bodies extended downwards from the heat-dissipating body, wherein the third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies and the dovetailed heat-dissipating fins.

8. The plane-type heat-dissipating structure according to claim 7, wherein the second heat-dissipating unit is integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body is one end surface of the hollow heat-dissipating body to provide a space for receiving at least one heat-generating element, and the third heat-dissipating unit is disposed over other end surface of the hollow heat-dissipating body.

9. The plane-type heat-dissipating structure according to claim 7, wherein the second heat-dissipating unit is integratedly disposed on a top surface of the hollow heat-dissipating body, so that at least one heat-generating element with a dovetailed bottom seat is retained on one end surface of the second heat-dissipating unit, and the third heat-dissipating unit is retained on another opposite end surface of the second heat-dissipating unit.

10. The plane-type heat-dissipating structure according to claim 1, further comprising: at least two third heat-dissipating units, wherein each third heat-dissipating unit has a heat-dissipating body, a plurality of heat-dissipating fins extended upwards from the heat-dissipating body, and a plurality of dovetailed retaining bodies extended downwards from the heat-dissipating body, wherein the third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies and the dovetailed heat-dissipating fins, wherein the second heat-dissipating unit is integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body is position on a central area of the first heat-dissipating unit to provide a space for receiving at least one heat-generating element, and the two third heat-dissipating units are respectively disposed over two opposite end surfaces of the hollow heat-dissipating body.

11. A method for manufacturing a plane-type heat-dissipating structure with high heat-dissipating effect, comprising:

using an extruding mold to integratedly extrude a first heat-dissipating unit and a second heat-dissipating unit, wherein the first heat-dissipating unit has a hollow heat-dissipating body, a plurality of supports integratedly formed in the hollow heat-dissipating body in order to divide an inner space of the hollow heat-dissipating body into a plurality of receiving spaces, and a plurality of microstructures integratedly formed on an inner surface of the hollow heat-dissipating body, and the second heat-dissipating unit is integratedly formed on an outer surface of the first heat-dissipating unit;

closing one end of the first heat-dissipating unit;

filling work liquid into the receiving spaces; and

extracting air from the receiving spaces and closing other opposite end of the first heat-dissipating unit to make the hollow heat-dissipating body become an evacuated hollow heat-dissipating body.

12. The method according to claim 11, wherein the extruding mold is composed of a mold body and a spindle, the mold body has a plurality of protrusion portions disposed on an inner wall thereof, the spindle has a forming portion extending forwards from one end thereof, and the first heat-dissipating unit and the second heat-dissipating unit are integratedly extruded by matching the protrusion portions and the forming portion.

13. The method according to claim 12, wherein the forming portion has a plurality of extending bodies connected to the spindle and extending forwards, many gaps respectively formed between every two extending bodies, and each extending body has a plurality of micro protrusions disposed on a top surface and a bottom surface thereof.

14. The method according to claim 11, wherein the first heat-dissipating unit has a plurality of grooves formed in the receiving spaces, each groove is between every two adjacent microstructures, and each microstructure has a rectangular prism, a cylinder, a taper or a dovetailed shape.

15. The method according to claim 11, wherein the second heat-dissipating unit has a plurality of heat-dissipating fins, and each heat-dissipating fin has a rectangular prism, a cylinder, a taper or a dovetailed shape.

16. The method according to claim 15, wherein the heat-dissipating fins are integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body provides a space for receiving at least one heat-generating element.

17. The method according to claim 16, further comprising: at least one third heat-dissipating unit having a heat-dissipating body, a plurality of heat-dissipating fins extended upwards from the heat-dissipating body, and a plurality of dovetailed retaining bodies extended downwards from the heat-dissipating body, wherein the third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies and the dovetailed heat-dissipating fins.

18. The method according to claim 17, wherein the second heat-dissipating unit is integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body is one end surface of the hollow heat-dissipating body to provide a space for receiving at least one heat-generating element, and the third heat-dissipating unit is disposed over other end surface of the hollow heat-dissipating body.

19. The method according to claim 17, wherein the second heat-dissipating unit is integratedly disposed on a top surface of the hollow heat-dissipating body, so that at least one heat-generating element with a dovetailed bottom seat is retained on one end surface of the second heat-dissipating unit, and the third heat-dissipating unit is retained on another opposite end surface of the second heat-dissipating unit.

20. The plane-type heat-dissipating structure according to claim 11, further comprising: at least two third heat-dissipating units, wherein each third heat-dissipating unit has a heat-dissipating body, a plurality of heat-dissipating fins extended upwards from the heat-dissipating body, and a plurality of dovetailed retaining bodies extended downwards from the heat-dissipating body, wherein the third heat-dissipating unit is retained on the second heat-dissipating unit by matching the dovetailed retaining bodies and the dovetailed heat-dissipating fins, wherein the second heat-dissipating unit is integratedly disposed on one part of a top surface of the hollow heat-dissipating body, and another part of the top surface of the hollow heat-dissipating body is position on a central area of the first heat-dissipating unit to provide a space for receiving at least one heat-generating element, and the two third heat-dissipating units are respectively disposed over two opposite end surfaces of the hollow heat-dissipating body.