Surface mount heat sink apparatus
A surface mountable heat sink apparatus for use with surface mount electronic components comprises a heat dissipating body and a plurality of solderable feet complying with Surface Mounting Technology (SMT). The heat dissipating body and the solderable feet are made of different materials and of unitary construction. The solderable feet project partially beyond one edge of the heat dissipating body. The surface mount heat sink apparatus and surface mount electronic component are touchlessly sandwiched and simultaneously soldered onto the solder drain pads on the printed circuit board. Heat dissipated from the surface mount electronic component is conductively transferred to the heat sink body through the solder drain pad, printed circuit board and solderable feet, and finally rejected to surroundings thereafter. Like all the SMT electronic components, the surface mount heat sink apparatus can be placed onto the printed circuit board manually or automatically by a pick-&-place automation equipment.
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STATEMENT REGARDING FEDERAL SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
FIELD OF THE INVENTIONThis invention generally relates to the art of heat sink apparatus, particularly, to a surface mount heat sink apparatus having solderable feet and heat dissipating body which are made of different materials and of unitary construction.
BACKGROUND OF THE INVENTIONSurface mount heat sink apparatus or surface mount heat sink assemblies of a limited variety of designs have been employed to dissipate heat generated by SMT electronic components or devices surface mounted (or soldered) on printed wiring or circuit boards to prevent the electronic components or devices from failure. More than ever before, today's electronic products are reducing the size and cost, increasing power dramatically, and upgrading frequently with new technologies. So that the surface mount heat sinks or heat sink assemblies used on printed wiring or circuit boards must be smaller in size, larger in surface areas and lower in cost to meet the trends.
Generally a heat sink is a piece of part made of any thermally conductive materials, such as Copper, Aluminum and Steel, etc. For better performance and higher heat transfer rate in a confined space, a heat sink usually has extended surface areas, called fins. In addition, for a surface mountable heat sink, the heat sink must be able to be soldered on a printed wiring or circuit board like any other surface mounting electronic components.
In order to meet the requirements of a surface mount heat sink, some stamped heat sinks with copper sheet material have been made available and used on the printed wiring or circuit boards with some SMT electronic components. An example of the latter may be seen in U.S. Pat. No. 5,311,395, this surface mount heat sink is formed with copper or copper alloy sheet which can be soldered on a printed wiring or circuit board. However this SMT heat sink or the like has at least three distinct disadvantages. First the copper material is expensive and heavy; second the sheet metal formed or stamped heat sink body has very limited surface areas within the specified volume, therefore the heat transfer rate is limited; third, the finish of the heat sink has to be solderable plating or coating, like tin plated, and can not be black anodized or painted, therefore it is limited to radiation heat transfer. Another example of the SMT heat sink is from AAVID Thermally, called Slalom Surface Mount Heat Sink. This SMT heat sink combines the copper solderable tags with stamped, pre-black anodized aluminum sheet by staking or self-riveting. This heat sink has the advantage of low cost in manufacturing and light in weight. However, it has, at least, two distinct disadvantages. First, the stamped aluminum heat sink body has very limited surface areas within the confined space; second, the staking joints for the solderable tags and the heat sink legs leave a “big” air gap and lower pressure in the contact areas between the two parts which creates huge thermal resistance in the contact interface areas of the two parts. Therefore it produces the lower heat transfer rate and increases higher temperature rise on the electronic component due to the “bottle-neck” thermal resistance.
Accordingly, what is needed is in the art of larger surface areas, lower cost, lighter weight and higher heat transfer rate heat sink apparatus which incorporates the advantages of different material properties, lower manufacturing cost and automated assembly operations.
SUMMARY OF THE INVENTIONA surface mountable heat sink apparatus for use with SMT electronic components comprises a heat dissipating body and a plurality of solderable feet. The heat dissipating body and the solderable feet are made of different materials and of unitary construction. The solderable feet project partially beyond one edge of the heat dissipating body. The surface mount heat sink apparatus and the SMT electronic component are touchless sandwiched and simultaneously soldered onto the solder drain pad on a printed circuit or wiring board. Heat dissipated from the surface mount electronic component is conductively transferred to the heat dissipating body through the solder drain pad, printed circuit board and solderable feet, and finally rejected into surroundings. Like all the SMT electronic components, the surface mount heat sink apparatus can be placed onto a printed circuit board manually or automatically by pick-&-place automation machines.
The unitary construction of the surface mount heat sink apparatus according to the present invention improves size, weight and power (SWaP) for thermal management products.
It is a further object of the present invention to provide higher heat transfer rate in a specified volume or form factor than those similar heat sinks on market by increasing the surface areas and surface emissivities of the heat sink body and reducing the interface thermal resistance between the solderable feet and the heat dissipating body.
It is yet a further object of the present invention to provide a lower cost and robust method for attaching the solderable feet into the heat dissipating body to minimize the interface thermal resistance in the contact areas of the two parts.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed descriptions of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
For operation, one can use surface mount heat sink apparatus 100 in a normal manner by first placing a SMT electronic component 200 onto solder pads 310 on PCB 300, them placing a surface mount heat sink apparatus 100 over SMT electronic component 200, so that SMT electronic component 200 fits in the U-shaped channel of heat sink apparatus 100. Meanwhile solderable feet 110 are resting on solder pads 310 on PCB 300 as shown in
Obviously the present invention provides the surface mount heat sink apparatus with advantages as listed below:
1). Larger surface areas in a confined space
2). Lower interface thermal resistance between solder feet and heat sink body
3). Ease of manufacturing
Although only a few embodiments of the present invention have been described, it should be understood that the present invention be embodied in many other specific forms without departing from the spirit or the scope of the present invention. The present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
Claims
1. A surface mount heat sink apparatus for use with at least one SMT electronic component; the apparatus comprising:
- (a) a heat dissipating body; and
- (b) a plurality of solderable feet;
- said heat dissipating body and said solderable feet being made of different materials and of unitary construction; said solderable feet configured having fixed and tight connection with said heat dissipating body;
2. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 1 wherein said heat dissipating body configured being a U-shaped member having two side walls or legs with continuous interior and exterior surfaces.
3. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 2 wherein said continuous exterior surfaces of said U-shaped member usually having fins attached or born thereto, and said continuous interior surfaces maybe having fins attached or born thereto;
4. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 2 wherein said the two side walls or legs, each having a circular aperture close to its free end;
5. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 4 wherein said circular aperture having a length “l”, an internal diameter of “d” and an arc “α” defined to be 180°<α<360°, preferred to be 270°.
6. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 1 wherein said solderable feet configured being a solid rod or wire having a length “L” and a diameter of “D”;
7. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 6 wherein said diameter (D) of said rod is slighter smaller than said internal diameter (d) of said circular aperture on said side wall or leg, expressed as D<d;
8. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 6 wherein said length (L) of said rod may be slighter longer than said length (l) of said circular aperture on said side wall or leg, expressed as L>l;
9. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 1 wherein said unitary construction being that said solderable feet configured to cooperatively engage a corresponding said circular aperture in said heat dissipating body fixedly and tightly;
10. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 9 wherein said solderable feet configured to cooperatively engage a corresponding said circular aperture in said heat dissipating body including partial body of each said foot projects beyond the boundary of said heat dissipating body;
11. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 1 wherein said fixed and tight connection configured to minimize the thermal resistance of the interfaces between said solderable feet and said heat dissipating body;
12. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 1 wherein said different materials referring to said heat dissipating body being made of conductive material, like aluminum, and said solderable feet being made of solderable material, like copper;
13. A surface mount heat sink apparatus for use with at least one SMT electronic component; the apparatus comprising:
- (a) a heat dissipating body;
- (b) a plurality of solderable feet; and
- (c) means for joining said solderable feet inside;
- said heat dissipating body and said solderable feet being made of different materials and of unitary construction; said solderable feet configured having fixed and tight interface connection with said heat dissipating body; said means for said unitary construction or joining of said heat dissipating body and said solderable feet together being very economical;
14. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 13 wherein said economical means of joining ensuring tight contact and minimizing the thermal resistance at the interface;
15. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 13 wherein said economical means including machiningless, weldingless and fixtureless assembly operations;
16. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 15 wherein said assembly operations including deforming, pressing and swaging, etc. simple mechanical work;
17. A surface mount heat sink apparatus for use with at least one SMT electronic component as recited in claim 15 wherein said assembly operations including taking the advantage of TEC (thermal expansion coefficient) of material properties of the two parts, and using temperature differentials in the assembly operation.
Type: Application
Filed: Dec 29, 2009
Publication Date: Jun 30, 2011
Inventor: Kechuan Kevin Liu (Weston, FL)
Application Number: 12/655,334