Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-03-01
2001-03-13
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C024S697100, C174S016300, C257S722000, C257S727000, C361S719000
Reexamination Certificate
active
06201699
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a heat sink and, more specifically, to a transverse mountable heat sink for use in an electronic device.
BACKGROUND OF THE INVENTION
Certain electronic and electrical components and devices mounted on printed circuit and wiring boards generate considerable operating heat that, unless controlled, may result in temperature related circuit or component failure. The generally preferred control method is to use a heat sink to transfer component heat to the air.
A heat sink can be made of any material with favorable heat transfer characteristics, such as copper, aluminum or steel. Aluminum is generally preferred because it is inexpensive, easy to work with, lightweight, and has good heat transfer characteristics. The heat sink and heat generating component are usually placed in direct contact with one another to more efficiently cool the component.
In most cases, after the heat sink absorbs component heat, the heat is transferred to the surrounding air by conduction or convection. In order to facilitate heat transfer, heat sinks frequently have “fins” to increase the total surface area that serves to conduct or convect heat.
A typical printed wiring or circuit board may have a number of heat generating devices. That is why it is not unusual to have a number of heat sinks on a single circuit board associated with heat generating devices and components. Because circuits are frequently enclosed in cabinets or other enclosures, a fan is used to move air across the heat sink and facilitate the transfer of heat to the air.
When a number of heat sinks are required, design factors in addition to temperature control must be taken into consideration. When a printed circuit or wiring board requires a number of heat sinks, the area of the board occupied by heat sinks will often constitute a significant fraction of the total board space. Similarly, a significant fraction of the total volume available to house a circuit will be taken up by heat sinks when a number of heat sinks are required. Because the total area required for heat sinks may be significant, the board size is often dictated by heat sink requirements. Another factor designers must consider is total heat sink weight when a number of heat sinks are required. Designers, therefore, must address heat dissipation problems from a space and weight viewpoint in designing electronic equipment in order to produce the highly valued small electronics system that some customers prefer.
Accordingly, what is needed in the art is a heat sink design that can efficiently cool a number of heat generating devices or components while utilizing a minimum amount of space on a printed wiring or circuit board and a minimum volume within the enclosure.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides a heat sink, which in one advantageous embodiment, includes a spine that has a width and first and second opposing sides that are oriented to be abnormal to the substrate when the heat sink is mounted on the substrate. The heat sink further includes an electronic device support leg that extends generally transversely from the first side and that is configured to support a heat generating electrical component thereon. Alternative embodiments of the present invention may include a plurality of such electronic device support legs.
A plurality of cooling fins extending from the spine are also included in the above-discussed embodiment. Moreover, each of the plurality of cooling fins has a depth that is substantially less than the width of the heat sink, which gives this unique heat sink an exceptional cooling efficiency. In particular advantageous embodiments, the depth to width ratio of the fins and spine, respectively, may range from about 1 to 5 or 1 to 10. However, in a particularly useful embodiment, the ratio is 1 to 5; that is, the depth of each fin is ⅕ of the width of the spine. In this embodiment, cooling fins extend from the first side and are positioned adjacent the electronic device support leg and, in certain applications, may be different lengths.
In another embodiment, the electronic device support leg depends from the first side of the spine, and the cooling fins extend substantially transversely from the second side and the first side.
In certain embodiments it may be advantageous to mount the heat sink to the board without the need of bulky screws. In such embodiments, the electronic device support leg includes mounting pins located on its end. The mounting pins are configured to cooperatively engage a corresponding mounting port on the substrate.
In yet another embodiment, each of the cooling fins include a leading edge that extends in a direction substantially transverse to the spine. In those embodiments where there is a plurality of electronic device support legs, the heat sink may further include electronic components attached to opposite sides of each leg. Spatial separation of the legs allows air to flow between the legs and over the devices, thereby providing a more efficient cooling system.
The electronic components may be attached to the electronic device support legs with a spring clip. In certain embodiments, the spring clip may be designed to have a low drag shape configured to delay separation of airflow passing over it. Likewise, in certain embodiments, the cooling fins may have a low drag shape configured to delay separation of airflow passing over them.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those who are skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention are hereinafter described that form the subject of the claims of the invention. Those who are 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 who are 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.
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Ayres John W.
Byrne Vincent
Fontana Edward C.
Stein Steven C.
Lucent Technologies - Inc.
Tolin Gerald
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