Thermal conductive apparatus
A thermal conductive apparatus includes a first electrode sheet, a second electrode sheet, a cooling sheet, and a polymer dielectric layer. The polymer dielectric layer physically contacts the first electrode sheet and the second electrode sheet via the top surface thereof, and the cooling sheet via the bottom surface thereof, and exhibits a coefficient of thermal conductivity above 1.0 W/mK. The interfaces between the first electrode sheet, the second electrode sheet, the cooling sheet, and the polymer dielectric layer include at least one micro-rough surface. The micro-rough surfaces include plural nodules thereon formed by electrodeposition. The first electrode sheet and the second electrode sheet are electrically insulated from each other and are connected to a power source and a heat-generating device to form a conductive circuit loop.
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1. Field of the Invention
The present invention relates to a thermal conductive apparatus and, more particularly, to a thermal conductive apparatus having at least one micro-rough surface with plural nodules.
2. Description of the Prior Art
Referring to
However, when applied to a heat-generating device (e.g., a light emitting diode or LED), the dielectric layer 13 cannot dissipate the heat efficiently and thus, the operating temperature of the heat-generating device increases. Consequently, the lifetime of the heat-generating device dramatically decreases or an issue of peeling occurs at the interface 131 between the first electrode 11, the second electrode 12, and the dielectric layer 13, and at the interface 132 between the dielectric layer 13 and the metal cooling sheet 14 due to poor bonding force caused by smooth contact surfaces after several thermal cycles. Finally, the heat conduction ability of the dielectric layer 13 is significantly degraded. In addition, the interfaces 131 and 132 lacking sufficient bonding force will cause damage to the traditional thermal conductive apparatus 10 and the heat-generating device carried thereon. SUMMARY OF THE INVENTION
The objective of the present invention is to provide a thermal conductive apparatus, which employ the interfaces, having at least one micro-rough surface, between two metal sheets and a polymer dielectric layer to exhibit high bonding strength and high heat dissipation efficiency. Accordingly, the thermal conductive apparatus of the present invention quickly reduces the operating temperature of a heat-generating device (e.g., an LED) carried thereon and the lifetime and reliability of the heat-generating device can both be enhanced.
In order to achieve the above objective, the present invention discloses a thermal conductive apparatus including a first electrode sheet, a second electrode sheet, a cooling sheet, and a polymer dielectric layer. Each of the first electrode sheet, the second electrode sheet, and the cooling sheet includes at least one micro-rough surface containing plural nodules. The nodules can be formed by electrodeposition. The polymer dielectric layer physically contacts the first electrode sheet and the second electrode sheet via the top surface thereof, and the cooling sheet via the bottom surface thereof. That is, the polymer dielectric layer is laminated between the first electrode sheet, the second electrode sheet and the cooling sheet in a physical contact manner. The polymer dielectric layer exhibits a coefficient of thermal conductivity above 1.0 W/mK, and the top and bottom surfaces thereof use micro-rough surfaces to physically contact the first and the second electrode sheets.
As for the manufacturing method of the thermal conductive apparatus of the present invention, first, a metal sheet and a cooling sheet are provided. Each of the metal sheet and the cooling sheet includes at least one micro-rough surface containing plural nodules. The nodules could be formed by electrodepositing. Second, a polymer dielectric layer is laminated between the metal sheet and the cooling sheet such that the at least one micro-rough surface physically contacts the top and bottom surfaces of the polymer dielectric layer. The polymer dielectric layer exhibits a coefficient of thermal conductivity above 1.0 W/mK. Third, the metal sheet is etched to form a first electrode sheet and a second electrode sheet that is electrically insulated from the first electrode sheet.
In addition, a first plating layer and a second plating layer are formed on the first electrode sheet and the second electrode sheet respectively to enhance the welding strength of the electrode sheets and to prevent oxidation on the first and the second electrode sheets. The structure including the above first plating layer, the second plating layer, the first electrode sheet, the second electrode sheet, the polymer dielectric layer, and the cooling sheet can be punched to form a thermal conductive apparatus with a specific shape.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be described according to the appended drawing in which:
The following will describe the manufacturing method of the thermal conductive apparatus of the present invention in detail with accompanying figures.
Referring to
Next, a polymer dielectric layer 23 is laminated between the metal sheet 21 and the cooling sheet 24 to form a multi-layered structure shown as
The polymer dielectric layer 23 is formed by heating, blending, and rolling a polymer material mixed with at least one heat-conductive dielectric filler at a proper ratio, in which the polymer material is more easily processed and treated than metals or ceramic material, and the polymer material is a dielectric itself, and thus is suitable for a matrix of the polymer dielectric layer 23. Most polymer materials could be used as the matrix of the polymer dielectric layer 23, and they are not limited to the following: (1) rubber material (e.g., natural rubber, silicone, polybutene gel, SBS (Polystyrene-butadiene-styrene), or CTBN (carboxyl terminated butadiene acrylonitrile rubber)); (2) thermoplastics (e.g., epoxy, polyurethane, or polyester); and (3) thermosetting plastics (e.g., polyethylene, polyvinylidene fluoride, polypropylene, nylon, polyester, ABS (Acrylonitrile Butadiene Styrene) plastic, or copolymer thereof). The above thermosetting plastics could include a functional group such as an amino group, an acidic group, a halide group, an alcohol group, and an epoxide group. In regard to the heat-conductive dielectric filler, it could be selected from at least one material with a coefficient of thermal conductivity above 1.0 W/mK, preferably above 5.0 W/mK, particularly above 10.0 W/mK. The resistivity of the heat-conductive dielectric filler must be above 108 Ω-cm, preferably 1010 Ω-cm, particularly 1012 Ω-cm. The amount of the heat-conductive dielectric filler is in the range of 20%-90%, preferably 30%-80%, particularly 40%-70%, by volume of the polymer dielectric layer 23. Higher concentration of the heat-conductive dielectric filler results in higher heat conduction of the polymer dielectric layer 23. The heat-conductive dielectric filler is mainly selected from metal nitride such as aluminum oxide (Al2O3), aluminum nitride (AlN), or boron nitride (BN). Others, like metal oxides, metal borides, metallic salts, metal carbides, silicone compounds, and graphite, are also suitable for the heat-conductive dielectric filler. For a specific purpose, an antioxidant or a water repellent could be mixed into the heat-conductive dielectric filler as long as the coefficient of thermal conductivity thereof is above 1.0 W/mK.
In addition, the heat-conductive dielectric filler could exhibit various shapes, e.g., spherical, cubical, hexagonal, flake, polygonal, spiky, rod, coral, nodular, or filament. The particle size distribution of the heat-conductive dielectric filler ranges from 0.01 μm to 30 μm, preferably from 0.1 μm to 10 μm, and has an aspect ratio below 100.
Referring to
Referring to
In another embodiment, the multi-layered structure of
The material of the bottom-cooling sheet is not limited to metal and can be any material with high heat dissipation rate.
Referring back to
When the thermal conductive apparatus of the present invention is applied to a heat-generating device (e.g., light emitting diode), similar to the configuration in
The devices and features of this invention have been sufficiently described in the above examples and descriptions. It should be understood that any modifications or changes without departing from the spirit of the invention are intended to be covered in the protection scope of the invention.
Claims
1. A thermal conductive apparatus, comprising:
- a cooling sheet;
- a first electrode sheet;
- a second electrode sheet electrically insulated from the first electrode sheet; and
- a polymer dielectric layer having a coefficient of thermal conductivity larger than 1.0 W/mK and being laminated between the first electrode sheet, the second electrode sheet and the cooling sheet in a physical contact manner, and the interfaces between the first electrode sheet and the polymer dielectric layer, the second electrode sheet and the polymer dielectric layer, and the cooling sheet and the polymer dielectric layer comprising at least one micro-rough surface.
2. The thermal conductive apparatus of claim 1, wherein the at least one micro-rough surface comprises a plurality of nodules.
3. The thermal conductive apparatus of claim 2, wherein the nodules consist essentially of size ranging from 0.1 μm to 100 μm, protrude perpendicularly to a surface of the cooling sheet and to surfaces of the first electrode sheet and the second electrode sheet and expand parallel to the surfaces of the cooling sheet, the first electrode sheet and the second electrode sheet with a distance from 0.1 μm to 100 μm.
4. The thermal conductive apparatus of claim 1, wherein the first electrode sheet and the second electrode sheet are formed by separating a metal sheet through an etching process.
5. The thermal conductive apparatus of claim 1, further comprising a first plating layer and a second plating layer respectively disposed on surfaces of the first electrode sheet and the second electrode sheet for increasing the welding strength between the first electrode sheet, the second electrode sheet, and a heat-generating device.
6. The thermal conductive apparatus of claim 1, wherein the first electrode sheet and the second electrode sheet are connected to a power source and a heat-generating device to form a conductive circuit loop.
7. The thermal conductive apparatus of claim 6, wherein the heat-generating device is a light emitting diode (LED).
8. The thermal conductive apparatus of claim 1, wherein the polymer dielectric layer comprises at least one heat-conductive dielectric filler.
9. The thermal conductive apparatus of claim 8, wherein the heat-conductive dielectric filler is selected from the group consisting of aluminum oxide (Al2O3), aluminum nitride (AlN) and boron nitride (BN).
10. The thermal conductive apparatus of claim 8, wherein the coefficient of thermal conductivity of the heat-conductive dielectric filler is above 10.0 W/mK.
11. The thermal conductive apparatus of claim 8, wherein the amount of the heat-conductive dielectric filler is in the range of 40%-70% by volume of the polymer dielectric layer.
12. The thermal conductive apparatus of claim 1, wherein the material of the cooling sheet is copper or aluminum.
13. The thermal conductive apparatus of claim 1, wherein the polymer dielectric layer comprises a plurality of polymer dielectric sub-layers.
14. The thermal conductive apparatus of claim 1, wherein the at least one micro-rough surface comprises an anti-oxidation layer.
15. The thermal conductive apparatus of claim 1, wherein the thickness of the cooling sheet is above 0.03 mm.
Type: Application
Filed: Dec 13, 2006
Publication Date: Jun 21, 2007
Applicant:
Inventors: David Chew Wang (Taipei), Jyh Yu (Kaohsiung)
Application Number: 11/638,208
International Classification: F28F 7/00 (20060101); F28F 13/18 (20060101); F28F 19/02 (20060101);