TWI671002B - heat sink - Google Patents

Abstract

A heat sink includes a metal layer and a first radiation heat dissipation layer. The metal layer includes a first surface and a second surface, and a plurality of first thermally conductive structures formed on the first surface, and each of the first thermally conductive structures has a size of 1-10 μm. The first radiation heat dissipating layer is located on the first surface of the metal layer and covers the first thermally conductive structures, and has a plurality of first protrusions, each of the first protrusions has a direction opposite to the metal layer The first heat radiation surface of the arc. The combination of the first heat-conducting structure and the first radiation heat-dissipating layer can reduce the interface thermal resistance and increase the heat conduction rate. The structural design of the first protrusions of the first radiation-heat-dissipating layer can increase the heat radiation. The effective radiation area improves the efficiency of heat radiation.

Description

heat sink

The invention relates to a heat sink, in particular to a heat sink capable of being attached to a heat source and dispersing heat.

In general, electronic components have a heating source that emits heat during operation, such as a central processing unit (CPU) of a tablet computer, a mobile phone chip in a smart phone, or a light emitting module in a light emitting diode (LED). It is necessary to attach a heat sink to the surface of the heat source for heat dissipation. The traditional heat sink uses copper, aluminum and other metals with good thermal conductivity as the metal layer, and one side of the metal layer is coated with an adhesive layer containing thermally conductive particles and having an adhesive force. The heat sink That is, the adhesive layer is adhered to a heat source in the above-mentioned electronic component, and the heat energy of the heat source will be transmitted to the surface of the heat sink, and finally discharged to the atmosphere through heat conduction and heat convection. However, today's electronic components have gradually increased the requirements for heat dissipation due to size reduction and density increase. The structure design of traditional heat sinks has not been able to further effectively improve heat dissipation efficiency, and the thermal convection efficiency of the surrounding environment When it is not good (such as a windless environment without air flow, or a small space such as in a mobile phone case), the convective heat dissipation effect of the heat sink is also greatly reduced. On the other hand, in addition to heat conduction or heat convection, heat can also be transmitted to the outside by means of heat radiation. The heat radiation emissivity of metals such as copper and aluminum is extremely low. The heat sink combined with high heat radiation emissivity material has gradually become the mainstream in research and application.

Referring to FIG. 1, a heat sink 1 having a material with high heat radiation emissivity is known. The heat sink 1 includes a metal layer 11 defining a vertical direction 10 and one side of the metal layer 11 in the vertical direction 10. An adhesive layer 12 and a radiating and radiating layer 13 covering the other side of the metal layer 11 in the vertical direction 10, the radiating and radiating layer 13 comprises a nano carbon material (for example, a nano carbon tube, a nano carbon, etc.). Balls, etc.) and composites after resin bonding. When the heat sink 1 is adhered to a heat source 2 through the adhesive layer 12, the thermal energy generated by the heat source 2 will pass through the metal layer 11 by heat conduction and be transmitted to the heat radiation heat dissipation layer 13, and then It is transmitted from the surface of the radiation heat dissipation layer 13 to the outside by means of thermal radiation and convection. This structural design makes the heat sink 1 especially in an environment with poor heat conduction and thermal convection effect (such as a windless environment or a small space). use.

However, the known heat sink 1 has the disadvantage that the thermal conductivity of the resin in the radiation heat dissipation layer 13 is not good, which reduces the heat conduction rate in the vertical direction 10 and further affects the heat dissipation efficiency. In addition, due to radiated heat and radiated effective surfaces It is known that the outer surface of the heat sink 1 is a flat plane, and the surface area available for radiating heat is limited, and the total amount of heat radiation cannot be further increased.

It is therefore an object of the present invention to provide a heat sink capable of overcoming at least one of the disadvantages of the prior art.

Therefore, the heat sink of the present invention includes a metal layer and a first radiation heat dissipation layer. The metal layer includes a first surface and a second surface on opposite sides, and a plurality of first thermally conductive structures protruding from the first surface. Each of the first thermally conductive structures has a protruding size of 1-10 μm. The first radiation heat dissipating layer is located on the first surface of the metal layer and covers the first thermally conductive structures, and has a plurality of first protrusions, each of the first protrusions has a direction opposite to the metal layer The first heat radiation surface of the arc.

The effect of the present invention is that the combination of the first heat-conducting structure and the first radiation heat-dissipating layer can achieve the effects of reducing the interface thermal resistance and increasing the heat conduction rate, and the first protrusions of the first radiation-heat-dissipating layer The structural design can increase the effective radiation area and improve the efficiency of thermal radiation.

3‧‧‧ heat sink

30‧‧‧Vertical orientation

31‧‧‧metal layer

311‧‧‧first surface

312‧‧‧Second Surface

313‧‧‧first thermally conductive structure

314‧‧‧Second heat conducting structure

32‧‧‧The first radiation heat dissipation layer

321‧‧‧The first protrusion

322‧‧‧first heat radiation surface

331‧‧‧Resin adhesive

332‧‧‧Release paper

34‧‧‧Second radiant heat dissipation layer

341‧‧‧ second protrusion

342‧‧‧Second heat radiation surface

4‧‧‧heat source

5‧‧‧shell

A‧‧‧arrow

D1‧‧‧ protruding size

D2‧‧‧Horizontal width

33‧‧‧ Adhesive layer

Other features and effects of the present invention will be described with reference to the drawings. It is clearly shown in the formula, in which: FIG. 1 is a schematic partial cross-sectional view illustrating a known heat sink attached to a heat source; FIG. 2 is a cross-sectional schematic view of a first embodiment of the heat sink of the present invention Figure 3 is a schematic partial sectional view illustrating the first embodiment after removing a release paper and attaching it to a heat source; Figure 4 is a sectional view of a second embodiment of the heat sink of the present invention Schematic diagram; FIG. 5 is an incomplete partial cross-sectional diagram illustrating the second embodiment after removing the release paper and attaching it to a housing and making contact with the heat source; FIG. 6 is a heat sink of the present invention A partial cross-sectional view of a third embodiment of the sheet; FIG. 7 is an incomplete partial cross-sectional view illustrating that the third embodiment removes the release paper and attaches it to the casing adjacent to the housing. One side of the heat source; and FIG. 8 is an incomplete cross-sectional schematic view illustrating that the third embodiment removes the release paper and attaches to the side of the housing away from the heat source.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are represented by the same numbers.

Referring to FIG. 2, a first embodiment of the heat sink 3 of the present invention includes a metal layer 31, a first radiation heat dissipation layer 32, and an adhesive layer 33.

The material of the metal layer 31 is selected from the group consisting of copper, aluminum, zinc, titanium, iron, cobalt, nickel, steel, tinplate, tungsten, tin, molybdenum, and alloys of the foregoing metals, and the thickness range is selected from 15 ~ 200μm, preferably, the thickness range is selected between 30 ~ 70μm. When the thickness of the metal layer 31 is too thin, there will be a shortcoming of insufficient mechanical strength. When the thickness is too thick, the overall volume and weight will be caused. The rise is not conducive to a thin design, so it is preferably within the above range. In the first embodiment, a piece of copper foil with a thickness of 35 μm is selected.

The metal layer 31 is a sheet-shaped body, and defines a vertical direction 30. The metal layer 31 includes a first surface 311 and a second surface 312 which are arranged at intervals along the vertical direction 30 and are opposite to each other. The first heat conducting structure 313 of the first surface 311.

The first heat-conducting structures 313 are arranged uniformly and finely, but the implementation is not limited to the uniform arrangement. Each of the first thermally conductive structures 313 has a tapered shape, and the protruding dimension D1 along the vertical plane direction 30 is 1-10 μm. Preferably, each of the first thermally conductive structures 313 protrudes along the vertical plane direction 30. D1 is 3 to 5 μm, and the significance of the value of the protruding dimension D1 is described later. The first thermally conductive structures 313 may be formed on the first surface 311 by a lithography process, an electrochemical deposition method, or a metal etching method. In the first embodiment, the first heat-conducting structures 313 are an oxidizing solvent etching solution prepared by using hydrogen peroxide and sulfuric acid. The metal layer 31 is dip-coated and sprayed at normal temperature (about 28 degrees Celsius). The surface is formed by etching.

The first radiation heat-dissipating layer 32 is located on the first surface 311 of the metal layer 31 and covers the first heat-conducting structures 313. The first radiation heat dissipating layer 32 includes 1% to 30% by weight of a nano carbon material, and 70% to 99% by weight of a polymer resin. Preferably, the first radiation heat dissipating layer 32 includes 5% to 10% by weight Nano-carbon materials, and 90wt% ~ 95wt% polymer resins, and the meaning of the above values is explained later. The nano carbon material is selected from graphite (Graphite), diamond (Diamond), diamond-like carbon (DLA), graphene (Graphene), fullerene (Fullerene), nano carbon tubes (Carbon Nanotubes), nano carbon balls (Carbon Nanocapsules), carbon fiber (VGCF), carbon black (Carbon Black), onion carbon (Nano-onion), carbon nano rolls (CarbonNnanoscroll), carbon nano cones (Carbon Nanohorns), stick carbon (Jumbo-fullerene) , Graphene ribbon (Graphene Nanoribbon) and a mixture of the foregoing materials. Specifically, the nano-carbon material of this embodiment is mainly composed of a composite of graphene and nano-carbon spheres, and the material of the polymer resin is an epoxy resin-based coating.

The first radiation heat-dissipating layer 32 has a plurality of first protrusions 321 protruding in a circular arc, and the first protrusions 321 are arranged adjacent to each other. Each of the first protruding portions 321 covers a plurality of first heat conducting structures 313 and has a first heat radiating surface 322 protruding in a direction opposite to the direction of the metal layer 31. In the first embodiment, the first radiation heat-dissipating layer 32 is a thermosetting resin composed of the nano carbon material and the polymer resin by using a micro gravure coating method. The ink is coated on the first heat-conducting structures 313 with an Engraved Cylinder, and the ink penetrates into the gaps between the first heat-conducting structures 313. After heating and drying, the ink can be cured to form the First radiation heat dissipation layer 32.

The thickness of the first radiation heat dissipation layer 32 is mainly controlled by adjusting the depth and mesh of the groove structure on the gravure engraving wheel in micro-gravure printing. The lateral width D2 of the protruding portion 321 is mainly controlled by the width of the groove structure and the density of the mesh. The thickness of the first radiation heat dissipating layer 32 is 2-20 μm. When the thickness is too thin, the first radiation heat dissipating layer 32 cannot completely cover the first heat conducting structures 313, and when the thickness is too thick, the It affects the rate of heat conduction during heat dissipation, so it is preferably in the above-mentioned size range. The lateral width D2 of each of the first protruding portions 321 is not specifically limited in the first embodiment. In specific implementation, the thickness of the first radiation heat dissipation layer 32 is about 5 μm, and the lateral width D2 of each first protruding portion 321 is about 50 μm.

It is added that a proper content of nano-carbon material can have a good heat radiation effect, but a content of nano-carbon material exceeding 30% by weight will reduce the fluidity and adhesion of the thermosetting resin before molding, and it is not easy to use microgravure. Coating by printing. In addition, the range of the protruding dimension D1 of the first thermally conductive structure 313 also needs to be matched with the first radiation heat dissipation layer 32. When the protruding size D1 is too small, the tip of each of the first thermally conductive structure 313 is away from the radiation heat dissipation layer 32 The surface 322 is too far away, which does not help much to improve the heat flow conduction efficiency. When the protruding dimension D1 is too large, It will cause the subsequent thicker first radiation heat dissipation layer 32 to cover the first heat conducting structures 313 and affect the efficiency of heat dissipation.

The adhesive layer 33 is located on the second surface 312 of the metal layer 31 and includes a resin adhesive 331 with adhesiveness adjacent to the metal layer 31 and a resin adhesive 331 removably attached to the resin adhesive 331 away from A release paper 332 on one side of the metal layer 31. The material of the resin adhesive 331 can be selected from natural rubber, styrene butadiene rubber (SBR), acrylic (polyacrylic acid copolymer), silicone resin and other elastomers, and can be added, for example, silicon carbide or These are thermally conductive particles such as alumina to improve the thermal conductivity of the adhesive layer 33. In the first embodiment, a material of the resin adhesive 331 is a transparent and transparent silicone resin, and the thickness of the resin adhesive 331 is 5 μm.

Referring to Figs. 2 and 3, when the first embodiment is used, the release paper 332 is first peeled from the resin adhesive 331, and the heat sink 3 is adhered to a heat source by using the viscosity of the resin adhesive 331. The heating source 4 can be a central processing unit (CPU) of a tablet computer, a chip of a smart phone, or a light emitting source of a light emitting diode (LED). The heat energy generated by the heating source 4 is as arrow A. As shown, the resin adhesive 331 and the metal layer 31 are penetrated by heat conduction, and because of the protruding structure design of the first heat conductive structures 313, the metal layer 31 and the first radiation heat dissipation layer 32 can be greatly increased. Contacting the heat conduction area, and the tapered design of the first heat conducting structures 313 allows thermal energy to penetrate deeply into the first radiation heat dissipation layer 32 and closer to the first heat radiation surface of each of the first protrusions 321 322. Thermal energy in the first radiating layer Inside 32, it will move to the first heat radiation surface 322 of each of the first protrusions 321 by heat conduction, and finally it will be discharged outward as heat radiation and heat convection as shown by arrow A. Because of the arc-shaped design of the first heat radiation surfaces 322, the effective heat radiation area can be increased. Compared with the radiation heat dissipation layer 13 whose flat surface of the heat sink 3 is known in FIG. The first heat radiation surface 322 can increase the overall effective heat radiation area by up to 57%.

It should be particularly noted that the heat dissipation design of the first protrusions 321 of the first radiation heat dissipation layer 32 in the present invention, when combined with the first heat conducting structures 313, can produce an excellent effect. If the first protrusions 321 are formed on a flat plane only by using the foregoing micro-gravure printing method, without the first thermally conductive structure 313 to accelerate heat flow into the first radiation heat dissipation layer 32, the first On the contrary, the thickness of the protruding portion 321 reduces the rate at which thermal energy is transmitted to the first heat radiation surfaces 322 in the vertical direction 30. In general, although the heat radiation efficiency is improved, the internal heat conduction efficiency is reduced, not the most. Best design. Similarly, when there are only the first heat-conducting structures 313, but the first radiation heat-dissipating layer 32 is not covered, although good thermal conductivity can be maintained, it is not conducive to conducting with the air in a windless environment or in a narrow space. Under the conditions of heat conduction and convection, the heat dissipation effect will be greatly reduced.

The foregoing first embodiment is cut into a 6 cm * 6 cm square, and a heat dissipation test is performed with a copper foil of the same size and a control group of the same size. The control method is substantially the same as that of the first embodiment, and the difference lies in the control The copper foil of the group has not been subjected to a surface etching treatment, that is, the first heat-conducting structure 313 as in the present invention is not formed. In addition, the control group uses a wire rod to uniformly coat the thermosetting resin ink to form a radiation heat-dissipating layer. It has a structure of the first protrusions 321 according to the present invention.

The three were respectively attached to a heater of 1.5cm * 5cm, and were heated under the same environment with a power of 3.96W, and the temperature of the heater body was measured to reach the equilibrium temperature. The test results are shown in Table 1. Compared with the control group, the first embodiment can reduce the temperature by 2.5 ° C, which indicates that the first embodiment has better heat dissipation performance than the conventional heat sink.

Referring to FIG. 4 and FIG. 5, the structure of a second embodiment of the heat sink 3 of the present invention is substantially the same as the first embodiment, except that the adhesive layer 33 is located on the first radiation heat dissipation layer 32. The second embodiment is also different from the first embodiment in application. The second embodiment is adhered to a casing 5 adjacent to the heat source 4 by the resin adhesive 331, and the second embodiment is The second surface 312 is in contact with the heat source 4. For example, if the heat source 4 is a chip of a mobile phone, and the case 5 is a phone case, this structure can be applied when the heat source 4 is not suitable for the resin adhesive 331 sticking condition.

At this time, as shown by arrow A in FIG. 5, the heat source 4 conducts thermal energy to the metal layer 31 and spreads uniformly within the metal layer 31, and the thermal energy in the metal layer 31 can be radiated through the first radiation to dissipate heat. The layer 32 is transferred outward to the casing 5 by means of heat radiation. With the above structure, the thermal energy generated by the heat source 4 can be dissipated to the metal layer 31 and further discharged to the outside, which can prevent the heat source 4 from being locally overheated. When the inspector performs safety inspection with a thermal imager, no obvious hot spots will be found, and the highest temperature of the equipment that can meet the safety regulations must not exceed 60 ° C.

Referring to FIG. 6, the structure of a third embodiment of the heat sink 3 of the present invention is substantially the same as that of the second embodiment, and the difference is that the structural design of the second surface 312 of the metal layer 31 is different. The metal layer 31 of the third embodiment further includes a plurality of second heat conducting structures 314 protrudingly formed on the second surface 312, and the heat sink 3 further includes a second surface 312 located on the second surface 312 of the metal layer 31. The second radiation heat dissipation layer 34 covers the second heat conducting structures 314.

The shape and preparation method of the second thermally conductive structures 314 are the same as those of the first thermally conductive structures 313 of the first embodiment, and the first thermally conductive structures 313 and The second thermally conductive structures 314. In addition, the shape and preparation method of the second radiation heat dissipation layer 34 are also the same as those of the first radiation heat dissipation layer 32 of the first embodiment. The second radiation heat dissipation layer 34 also has a plurality of second protrusions 341. One second protrusion 341 has an opposite direction A second heat radiating surface 342 that protrudes in the direction of the metal layer 31.

Referring to FIG. 7, the application method of the third embodiment is similar to that of the second embodiment of FIG. 5, except that the second surface 312 of the heat sink 3 is not in contact with the heat source 4. As shown by arrow A, the heat sink 3 uses the heat radiation effect of the second radiation heat dissipation layer 34 to absorb the heat energy from the heat source 4 and uses the second heat conducting structures 314 to quickly conduct the heat energy and The heat is dissipated into the metal layer 31, and the heat energy is discharged to the casing 5 from the first heat conducting structures 313 and the first radiation heat dissipation layer 32. With the above structure, although the heat sink 3 is not in direct contact with the heat source 4, it can also achieve the effect of equalizing heat.

Referring to FIG. 8, there is another use aspect of the third embodiment. The user can adhere the resin adhesive 331 of the heat sink 3 to one side of the casing 5 away from the heat source 4. As shown by arrow A, when heat energy is transmitted from the heat source 4 to the casing 5, the temperature of the casing 5 will rise. At this time, the heat sink 3 can absorb the heat from the first radiation heat dissipation layer 32. The thermal energy of the casing 5 is dissipated into the metal layer 31 after thermal conduction, and finally the second radiating and radiating layer 34 is used to discharge the thermal energy to the external environment, which can quickly reduce the temperature of the casing 5.

In summary, the heat sink 3 of the present invention uses the combination of the first heat-conducting structure 313 and the first radiation heat-dissipating layer 32 to achieve the effects of reducing the interface thermal resistance and increasing the heat conduction rate, and the first radiation heat-dissipating layer 32 The structural design of the first protrusions 321 can increase the effective radiation area during thermal radiation and improve the efficiency of thermal radiation. Rate, it can indeed achieve the purpose of cost invention. The different covering positions of the adhesive layer 33 enable the heat sink 3 to provide different effects when being adhered to different positions. Finally, the first surface 311 and the second surface 312 of the heat sink 3 are respectively formed with the first heat conducting structures 313 and the second heat conducting structures 314 and are respectively formed by the first radiation heat dissipation layer 32 and the Covered by the second radiation heat dissipation layer 34, this structural design makes the heat sink 3 more variable in application methods.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, any simple equivalent changes and modifications made according to the scope of the patent application and the contents of the patent specification of the present invention are still Within the scope of the invention patent.

Claims (10)

A heat sink includes a metal layer including a first surface and a second surface on opposite sides, and a plurality of first thermally conductive structures protrudingly formed on the first surface, and each of the first thermally conductive structures protrudes. The size is 1 ~ 10μm; and a first radiation heat dissipation layer is located on the first surface of the metal layer and covers the first heat conducting structures. The first radiation heat dissipation layer has a plurality of first protrusions, each of which A protruding portion has a first heat radiation surface that is arcuate in a direction opposite to the metal layer. The heat sink according to claim 1, further comprising an adhesive layer on the second surface. The heat sink according to claim 1, further comprising an adhesive layer on the first radiation heat dissipation layer and covering the first radiation heat dissipation layer. The heat sink according to claim 1, wherein the metal layer further includes a plurality of second heat conducting structures protrudingly formed on the second surface, and each of the second heat conducting structures has a protrusion size of 1 to 10 μm. It includes a second radiation heat dissipation layer located on the second surface of the metal layer and covering the second heat conducting structures, and an adhesive layer located on the first surface and covering the first radiation heat dissipation layer, the second The radiating and radiating layer has a plurality of second protruding portions, and each of the second protruding portions has a second heat radiating surface that arcs in a direction opposite to the metal layer. The heat sink according to any one of claims 2 to 4, wherein the adhesive layer includes a resin adhesive having a viscosity adjacent to the metal layer, and a resin adhesive that is detachably attached to the resin adhesive. Release paper away from one side of the metal layer. The heat sink according to claim 4, wherein the thickness of the second radiation heat dissipation layer is the same as the thickness of the first radiation heat dissipation layer. The heat sink according to claim 1 or 6, wherein the thickness of the first radiation heat dissipation layer is 2-20 μm. The heat sink according to claim 4, wherein the material of the second radiation heat dissipation layer is the same as the material of the first radiation heat dissipation layer. The heat sink according to claim 1 or 8, wherein the first radiation heat dissipation layer comprises a nano carbon material of 1 wt% to 30 wt%, and a polymer resin of 70 wt% to 99 wt%. The heat sink according to claim 9, wherein the nano carbon material is selected from graphite, diamond, diamond-like carbon, graphene, fullerene, nano carbon tube, nano carbon ball, carbon fiber, soot, and onion Carbon, carbon nano rolls, carbon nano cones, carbon rods, graphene ribbons, and mixtures of the foregoing materials.