WO2013049810A1

WO2013049810A1 - Heat sink for electrical or electronic equipments and method of manufacturing the same

Info

Publication number: WO2013049810A1
Application number: PCT/US2012/058293
Authority: WO
Inventors: Baohua Song; Yan Lin; Xiaoling Li; Haitao PENG; Lihui NAN
Original assignee: Alcoa Inc.
Priority date: 2011-09-29
Filing date: 2012-10-01
Publication date: 2013-04-04
Also published as: CN102510702A

Abstract

This invention discloses a heat sink for electric or electronic equipments, comprising: a substrate; and at least one fin groups, each of which comprises a plurality of fins, the fins comprising connecting portions and fin bodies protruding from the connecting portions, and engaging with the substrate by the connecting portions; wherein both of the substrate and the finstock of the fins are of metals, and at least one of the substrate and the finstock of the fins is a multi-layer aluminum sheet; and wherein the connecting portions and the fin bodies of the plurality of fins are formed from one single finstock, and the at least one fin groups are brazed to the surface of the substrate.

Description

Heat Sink for Electrical or Electronic Equipments and Method of Manufacturing the

Same

Cross-Reference to Related Applications

This patent application claims the benefit of, and priority to, Chinese Patent Application No. 201 110304514.2, filed September 29, 2011 the entire content of which is herein incorporated by reference in full.

Technical field

The present disclosure relates to a heat sink. In particular, the present disclosure relates to a heat sink for electrical or electronic equipments and a method of manufacturing the same.

Background art

A heat sink for electrical or electronic equipments generally comprise a substrate and fins, and is made of copper alloy, aluminum alloy, magnesium alloys and other materials with high thermal conductivity. The substrate and fins of the heat sink can be structured as one-piece or be formed separately and then assembled together. One-piece heat sinks, such as machining type heat sinks, extruding type heat sinks, die-casting type heat sinks, etc., can be manufactured through processes of machining, extruding, or die-casting; and assembled heat sinks, such as gear type heat sinks, folding type heat sinks, etc., can be manufactured by joining the substrate and fins together.

The most feasible approaches to increase heat dissipation efficiency of a heat sink are to increase the fin area, or to increase the pin/fin ratio (i.e., the ratio of fin height/spacing of fins). These are usually done by increasing the fin height or decreasing the spacing of fins, which will result in increasing the size and weight of the heat sink, and also significantly increasing the manufacturing difficulty and production cost. The only way to increase the fin area or pin/fin ratio, without increasing the heat sink size and weight, is to decrease the fin thickness and consequently to increase the number of fins. However, for one-piece heat sinks, such as extruded type heat sinks, the thickness of fins can be reduced only to a certain limit, and the pin/fin ratio is usually less than 20. It is difficult to produce thinner fins using the traditional manufacturing methods (e.g., mechanical machining, extruding, die-casting, etc.), while the production cost will drastically increase. For assembled heat sinks, the conventional joining manufacturing flow paths, though good with high pin/fin ratio up to 60, are usually very costly for mass production because of the complexity of manufacturing flow paths.

Current electrical or electronic equipments (e.g., flat panel display devices, LED lights, etc.) are demanding larger power capacity with decreasing size and weight. This implies the need to provide a more efficient heat dissipation solution with heat sinks of smaller size and lower weight. Clearly, the above described traditional heat dissipation solution cannot meet such a demand.

Contents of this invention

In one non-limiting aspect of the present disclosure, heat sinks and methods of manufacturing the same are provided. The heat sinks may have a generally compact structure. The heat sink may effectively increase the heat dissipation area, greatly improving the heat dissipation efficiency, and thus extensively meet the increasing heat dissipation requirements of electrical or electronic equipments.

In one further aspect of the present disclosure, a heat sink for electric or electronic equipments may comprise: a substrate; and at least one fin groups, each of which comprises a plurality of fins, the fins comprising connecting portions and fin bodies protruding from the connecting portions, and engaging with the substrate by the connecting portions; wherein both of the substrate and the finstock of the fins may be of metals, and at least one of the substrate and the finstock of the fins may be a multi-layer aluminum sheet; and wherein the connecting portions and the fin bodies of the plurality of fins may be formed from one single finstock, and the at least one fin groups may be brazed to the surface of the substrate. In an embodiment, at least one cooling passage, filled with a flowable cooling medium, may be arranged within the substrate.

In an embodiment, the cross-sectional shapes of the fin bodies along the height direction of the fins may be selected from at least one from the group consisting of triangle, rectangle, trapezoid, curved shape.

In an embodiment, the cross-sectional shapes of the fin bodies along the height direction of the fins are straight lines, and the fin bodies, in the form of planar thin sheets, may be spaced apart from each other.

In an embodiment, the thickness of the fin bodies may be about 0.01-1 mm.

In an embodiment, the connecting portions are periodically arranged on the substrate.

In an embodiment, the fin bodies may have extending arms extending from the side surfaces thereof.

In an embodiment, the extending arms may be symmetrical distributed along the lengthwise direction of the fins.

In an embodiment, the extending arms may be staggered distributed along the lengthwise direction of the fins.

In an embodiment, the extending arms may be distributed in multiple lines along the height direction of the fins.

In an embodiment, micro textures may be formed on the surface of the fins.

In an embodiment, the surface of the fins may be coated with materials of high heat radiation coefficient, or otherwise be treated into black or other dark colors. In one further aspect of the present disclosure, a method of manufacturing a heat sink for electric or electronic equipments including a substrate and a plurality of fins may comprise: a) selecting suitable metals for the substrate and the finstock of the fins, respectively, at least one of the substrate and the finstock of the fins being a multi-layer aluminum sheet; b) forming one single finstock into the plurality of fins, which comprise connecting portions and fin bodies protruding from the connecting portions; and c) brazing the fins to the substrate.

In an embodiment, the step b) may form one single finstock into the plurality of fins by bending process.

In an embodiment, the fin bodies, in the form of planar thin sheets, may be spaced apart from each other.

In an embodiment, the step of embossing the finstock to manufacture micro-textured structure thereon may be provided between steps a) and b).

In an embodiment, the step of stamping the finstock to manufacture extending arms extending therefrom may be provided between steps a) and b).

In an embodiment, the step of cutting the fins into suitable sized fin groups may be provided between steps b) and c).

In an embodiment, the step c) may further comprise fixing the fins to the substrate, putting the fixed fins and substrate into a brazing furnace and raising the temperature in the brazing furnace to the brazing temperature, the fins brazing jointed with the substrate to form the heat sink.

In an embodiment, the step of proceeding the final surface cleaning of the fins and the substrate may be provided after step c). In an embodiment, the step of coating the surface of fins with materials of high heat radiation coefficient, or otherwise treating the surface of fins into black or other dark colors may be provided after step c).

In one further aspect of the present disclosure, a flat panel display device may include the heat sink as describe above.

In one further aspect of the present disclosure, a LED light may include the heat sink as describe above.

Description of figures

The preferred embodiment of the present disclosure will be described with reference to the accompanying drawings, wherein:

Fig. 1 is a cross-sectional view of the structure of the heat sink according to one embodiment of the present disclosure.

Figs. 2a-2c are cross-sectional views of the fin bodies along the height direction of the fins.

Figs. 3a-3b are perspective views of the fins having straight and wave profiles along the lengthwise direction thereof.

Fig. 4 is a perspective view of the extending arms located on the fins of the heat sink according to one embodiment of the present disclosure.

Fig. 5 is a cross-sectional view of the micro-textures on the surface of the fins.

Fig. 6 is a cross-sectional view of the coatings with high heat radiation coefficient on the surface of the fins.

Fig. 7 is a perspective view of fin groups on the substrate. Fig. 8 is a diagram of the manufacturing flow path for the fins. Fig. 9 is a perspective view of the finished fin groups.

Fig. 10 is a perspective view of the fins after processes of embossing, stamping, and bending. Fig. 1 1 is a diagram of the joining flow path between the fins and the substrate. Mode of carrying out this invention

Now one embodiment of the present disclosure will be described by referring to the drawings, wherein the same components throughout the drawings will be designated with the same reference numerals.

A non-limiting illustrative embodiment of a heat sink of the present disclosure is illustrated in Fig. 1. The heat sink 1 therein may comprise two main components, a substrate 2 and fins 3. To facilitate illustration below, the direction along the thickness of the fins 3 is called the x- axis direction; the direction along the length of the fins 3 is called the y-axis direction; and the direction along the height of the fins 3 called the z-axis direction.

The substrate 2 may be made of metal, and closely contact with heat sources. The substrate 2 can be solid, or be arranged with at least one cooling passage therein filled with a flowable cooling medium.

The finstock of the fins 3 may be metal sheet, and the fins 3 may comprise periodically arranged connecting portions 3a and fin bodies 3b protruding from the connecting portions 3a. The fin bodies 3b may have different cross-sectional shapes, e.g., triangle, rectangle, trapezoid, curved shape, etc., along the z-axis direction, as shown in Figs. 2a-2c. Preferably, the cross-sectional shape of the fin bodies 3b along the z-axis direction can be vertical or inclined straight lines, as shown in Fig. l, and the fin bodies 3b, in the form of planar thin sheets, may be spaced apart from and preferably parallel with each other. The connecting portions 3a may be used to join the adjacent fin bodies 3b, and closely engage with the substrate 2. In some examples, the cross-sectional shapes of the connecting portions 3a along the z-axis direction can be points, shown in Figs. 2b and 2c, and the connecting portions 3a may linearly contact with the substrate 2 along the y-axis direction. The connecting portions 3a and fin bodies 3b of the fins 3 may be formed from one single finstock through bending process, and then the connecting portions 3 a may be brazed to the surface of the substrate 2.

The substrate 2 and the finstock of the fins 3 can be of any suitable metal materials, and preferably metals with high thermal conductivity, such as aluminum, copper, magnesium and their alloys. The metal materials for the substrate 2 and the finstock of the fins 3 can be the same or different, and at least one of the substrate 2 and the finstock of the fins 3 may be made of a multiple-layer aluminum brazing sheet.

The so-called multiple-layer aluminum brazing sheet is a multi-layer aluminum sheet made by rolling laminated aluminum ingots containing different alloys; at least one layer is a brazing layer. For example, for the three-layer aluminum brazing sheet, the three layers would be upper brazing layer, core layer, and lower brazing layer, respectively. The brazing layers can be, for example, 4XXX aluminum alloy, and are used to join the fins to the substrate by brazing, and the core layer can be, for example, 3XXX aluminum alloy, 1XXX aluminum alloy or other aluminum alloys, and is used to enhance the strength of the fins. For the five-layer aluminum brazing sheet, the five layers would be upper brazing layer, intermediate layer, core layer, intermediate layer, and the lower brazing layer, respectively. The materials of the brazing layers and core layer are similar with those of the three layers. The intermediate layers can be, for example, 5XXX aluminum alloy or other alloys, and are used to enhance the corrosion resistance of the fins. According to Aluminum Alloys Designation System regulated in the National Standard GB/T 16474-1996, 1XXX represents pure aluminum (i.e., the aluminum content not less than 99.00%), 3XXX represents aluminum alloy with manganese as the main alloying element, 4XXX represents aluminum alloy with silicon as the main alloying element, and 5XXX represents aluminum alloy with magnesium as the main alloying element. Without wishing to be bound by the theory, the applicants believe that the fins may be used to increase the heat dissipation efficiency. The geometric parameters of the fins 3, including fin height, spacing of fins, etc., can be varied according to the actual heat dissipation request, wherein the fin height refers to the vertical distance from the surface of the substrate 2 to the tips of the fins 3 along the z-axis direction, and the spacing of fins refers to the horizontal distance between the central vertical axes of two adjacent fins 3.

As shown in Figs. 3a and 3b, for better heat conduction between fins and airflow, the profile of fins 3 may be designed to be straight, wavy or other metamorphosis along the y-axis direction.

As shown in Fig. 4, a series of small extending arms 4 may be manufactured on each side of the fin bodies 3b by stamping process. The extending arms 4 may extend from the side surfaces of the fin bodies, leaving openings 5 formed on the respective side surfaces. The extending arms 4 and openings 5 of the fins 3, on one hand, may increase the whole dissipation area of the fins 3, and on the other hand, may promote the flow of the air, increasing the efficiency for taking the heat away from the fins 3. According to the actual need, the extending arms 4 can be arranged into a symmetrical or staggered distribution along the y-axis direction, and into multiple line distribution along the z-axis direction.

As shown in Fig. 5, the fins 3 may have micro textures throughout the surface thereof for better contact with airflow, so to improve the thermal conductivity. The micro-textures may be of any shapes, such as triangle, rectangular, curve, as well as well as irregular shapes etc., and be manufactured very cost effectively by embossing process. Also, as shown in Fig. 6, the whole surface of fins 3 may be coated with materials 7 of high heat radiation coefficient, such as graphite, or otherwise be treated into black or other dark colors, for better heat dissipation.

As shown in Fig. 7, the fins 3 on the substrate 2 can be divided into different groups. The layouts among fin groups may be designed based on the simulation results of heat dissipation, so as to facilitate heat conductivity between the fins 3 and airflow and easy installation of the heat sink.

Now the manufacturing method of the heat sink in one embodiment of the present disclosure is described. Fig. 8 illustrates the manufacturing flow path of fins 3. In step 801, a suitable finstock for the fins 3, including the number of layers of the metal sheet, and the material, length, width, and thickness for each layer, etc., may be selected according to applications and customer requirements, such as corrosion resistance, strength, etc. In step 802, the finstock may be embossed to manufacture micro-textured structure with a certain density on the surface thereof, and then, the finstock with micro-textured structures may be slit to width along x-axis direction. In step 803, the finstock may be stamped to manufacture extending arms extending from the sheet surface. The extending arms can be arranged into a symmetrical or staggered distribution along the y-axis direction, and into multiple line distribution along the z-axis direction. In step 804, the single finstock may be formed into periodically arranged connecting portions 3a and fin bodies 3b protruding from the connecting portions by bending process, according to the requested geometrical parameters, e.g., cross-sectional shapes of the fins along the z-axis direction, fin height, spacing of fins, etc.. Finally, in step 805, the fins 3 may be cut to requested length along y-axis direction to form multiple fin groups, as shown in Fig. 9. It is appreciated that if the fins are designed to have no micro-texture or extending arm structure, the corresponding step 802 or 803 can be omitted in the manufacturing flow path of the fins.

Fig. 10 shows the fin groups after the processes of embossing, stamping, and bending, which will be subsequently brazed to the substrate 2. As shown in Fig. 1 1, in step 1101, a suitable metal sheet for the substrate 2, including the number of layers, the material, length, width, and thickness for each layer, and whether there are cooling passages in the sheet, etc., may be selected according to applications and customer requirements. It should be noted that at one of the substrate 2 and the finstock of the fins 3 are made of a multiple-layer aluminum brazing sheet. In step 1 102, one or more fin groups may be fixed to the substrate 2 by jigs, with the connecting portions 3a of the fins closely engaged with the substrate 2. In step 1 103, the fixed fin groups and substrate 2 may be put into a brazing furnace and the temperature within the furnace may be raised to the brazing temperature (i.e., the temperature higher than the melting point of the brazing layer and lower than the melting point of the core layer or intermediate layer). The fin groups may be brazing jointed with the substrate to form the heat sink 1. In step 1 104, final surface cleaning of the heat sink may be needed for the heat sink 1. In addition, the surface of the fins 3 can be coated with materials 7 of high heat radiation coefficient, such as graphite, or otherwise be treated into black or other dark colors for better heat dissipation. It is appreciated that if the fins are not intended to be coated with materials of high heat radiation coefficient or be treated into black or other dark colors, then the corresponding operations in step 1 104 can be omitted in the manufacturing flow path of the heat sink.

The heat sink disclosed in one embodiment of the present disclosure has clear advantages in heat dissipation performance and manufacturing cost over prior art heat sinks.

Firstly, the manufacturing processes of the heat sink in one embodiment of the present disclosure are much simpler. Fins made of fnstock can be integrally formed through bending process at room temperature, and then be joined with the substrate by the well-established brazing process. The processes are much easier for mass production and consequently results in much lower manufacturing cost.

Furthermore, the structures of micro-textures, extending arms, and coatings of high heat radiation coefficient can be easily added to the fins of the heat sink of one embodiment of the present disclosure through processes of embossing, stamping, and coating, which will promote sufficient heat exchange between the fin surface and airflow, and improve the heat dissipation efficiency. On the contrary, in case of fins in traditional heat sinks, the adding of those structures requires much more complicated processes.

Second, for the heat sink of one embodiment of the present disclosure, the main parameters associated with the heat dissipation efficiency, e.g., fin height, spacing of fins, etc., can be arbitrarily adjusted according to the design request, which is not limited to the manufacturing processes. As the fins of one embodiment of the present disclosure are made by metal sheets through bending, the fin body thickness can be up to about 0.1 mm to about 1mm, or even as small as about 0.01 mm. This provides much higher pin/fin ratio than the traditional heat sinks. The pin/fin ratio for the traditional one-piece heat sinks is less than 20, and is less than 60 for the traditional assembled heat sinks. The pin/fin ratio of one embodiment of the present disclosure can be up to 100-500, or even more, and thereby the heat dissipation area can be significantly increased. For example, the heat dissipation area of the heat sink of one embodiment of the present disclosure can increase by 25%-500% compared to the same size of traditionally extruded type heat sinks. Thus, the heat dissipation efficiency of the heat sinks of one embodiment of the present disclosure is greatly improved.

Finally, the heat sinks of one embodiment of the present disclosure have compact structure with much smaller size and lower weight compared to the traditional heat sinks, and the material usages are correspondingly reduced. The compact structure provides more freedom for various design, meeting the current trends in electrical or electronics equipments (e.g., flat panel display devices, LED lights, etc.), for which characteristics such as being thin, lightweight, and appearance are dominant factors for the next generation products.

While the present disclosure has been described with respect to one embodiment, the present disclosure can be further modified within the spirit and scope of the present disclosure. The present disclosure is therefore intended to cover any variations, uses, or adaptations of the present disclosure using its general principle. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which the present disclosure pertains and which fall within the limits of the appended claims.

Claims

1. A heat sink for electric or electronic equipments, characterized in that the heat sink comprises:

a substrate; and

at least one fin groups, each of which comprises a plurality of fins, the fins comprising connecting portions and fin bodies protruding from the connecting portions, and engaging with the substrate by the connecting portions;

wherein both of the substrate and the finstock of the fins are of metals, and at least one of the substrate and the finstock of the fins is a multi-layer aluminum sheet; and

wherein the connecting portions and the fin bodies of the plurality of fins are formed from one single finstock, and the at least one fin groups are brazed to the surface of the substrate.

2. The heat sink as claimed in claim 1, characterized in that at least one cooling passage, filled with a flowable cooling medium, is arranged within the substrate.

3. The heat sink as claimed in claim 1, characterized in that the cross-sectional shapes of the fin bodies along the height direction of the fins are selected from at least one from the group consisting of triangle, rectangle, trapezoid, curved shape.

4. The heat sink as claimed in claim 1, characterized in that the cross-sectional shapes of the fin bodies along the height direction of the fins are straight lines, and the fin bodies, in the form of planar thin sheets, are spaced apart from each other.

5. The heat sink as claimed in claim 4, characterized in that the thickness of the fin bodies is about 0.01-1 mm.

6. The heat sink as claimed in claim 1 , characterized in that the connecting portions are periodically arranged on the substrate.

7. The heat sink as claimed in any one of claims 1-6, characterized in that the fin bodies have extending arms extending from the side surfaces thereof.

8. The heat sink as claimed in claim 7, characterized in that the extending arms are symmetrical distributed along the lengthwise direction of the fins.

9. The heat sink as claimed in claim 7, characterized in that the extending arms are staggered distributed along the lengthwise direction of the fins.

10. The heat sink as claimed in claim 7, characterized in that the extending arms are distributed in multiple lines along the height direction of the fins.

11. The heat sink as claimed in any one of claims 1-6, characterized in that micro textures are formed on the surface of the fins.

12. The heat sink as claimed in any one of claims 1-6, characterized in that the surface of the fins is coated with materials of high heat radiation coefficient, or otherwise be treated into black or other dark colors.

13. A method of manufacturing a heat sink for electric or electronic equipments including a substrate and a plurality of fins, comprising:

a) selecting suitable metals for the substrate and the finstock of the fins, respectively, at least one of the substrate and the finstock of the fins being a multi-layer aluminum sheet; b) forming one single finstock into the plurality of fins, which comprise connecting portions and fin bodies protruding from the connecting portions; and

c) brazing the fins to the substrate.

14. The method as claimed in claim 13, wherein the step b) forms one single finstock into the plurality of fins by bending process.

15. The method as claimed in claim 14, wherein the fin bodies, in the form of planar thin sheets, are spaced apart from each other.

16. The method as claimed in claim 13, wherein the step of embossing the finstock to manufacture micro-textured structure thereon is provided between steps a) and b).

17. The method as claimed in claim 13, wherein the step of stamping the finstock to manufacture extending arms extending therefrom is provided between steps a) and b).

18. The method as claimed in claim 13, wherein the step of cutting the fins into suitable sized fin groups is provided between steps b) and c).

19. The method as claimed in claim 13, wherein the step c) further comprises fixing the fins to the substrate, putting the fixed fins and substrate into a brazing furnace and raising the temperature in the brazing furnace to the brazing temperature, the fins brazing jointed with the substrate to form the heat sink.

20. The method as claimed in claim 13, wherein the step of proceeding the final surface cleaning of the fins and the substrate is provided after step c).

21. The method as claimed in claim 13, wherein the step of coating the surface of fins with materials of high heat radiation coefficient, or otherwise treating the surface of fins into black or other dark colors is provided after step c).

22. A flat panel display device, including the heat sink as claimed in any one of claims

1-12.

23. A LED light, including the heat sink as claimed in any one of claims 1-12