Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-04-23
2001-06-26
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S185000, C174S016300, C257S719000, C257S727000, C361S710000
Reexamination Certificate
active
06252773
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a heat transfer device and, more specifically, to a heat transfer device that can be used alone or as a unit in a modular heat control system.
BACKGROUND OF THE INVENTION
A principle concern of electronic circuit designers is controlling the heat that is generated during operation of the circuit. Control of heat is vital to prevent component or circuit failure caused by heat buildup. The generally preferred method to control circuit and component heat is to dissipate it into the atmosphere around the circuit before temperatures rise to a damaging level. To do this, designers usually associate heat transfer devices, such as heat sinks, with heat generating components in the circuit. Heat sinks are designed to absorb the heat from the components and radiate the heat into the surrounding atmosphere.
Heat transfer devices are generally composed of a material with favorable heat transfer, or thermal conductive, characteristics; that is, the material should be able to absorb heat and radiate heat into the surrounding atmosphere in an efficient manner. Several metals have favorable thermal conductive characteristics, including copper, aluminum, steel, and their alloys. Any one of these materials can be used as a heat sink, but aluminum is generally the preferred material because copper is expensive and steel is not very malleable. Another reason aluminum is favored is that extrusion processes are preferred in the manufacture of heat transfer devices, and such processes favor aluminum.
Commercially available heat transfer devices come in a variety of shapes and sizes. Designers have developed a number of methods to combine these commercially available devices with heat generating circuits and components. These methods have generally been satisfactory, except in the case of low profile electronic systems. It has been found that very few of the commercially available heat transfer devices are suitable for controlling the heat generated by a large number of components in a very limited space.
Most commercially available heat transfer devices can control the heat of only one or two electronic components. This means that several heat transfer devices may be required for a single circuit. This may be acceptable for larger electronic systems, but is a distinct disadvantage where the electronic system is a compact or low profile system for which space is limited.
In many cases, heat spreaders can be mounted on the circuit substrate with heat generating components mounted on the spreaders. In the case of compact systems, such spreaders frequently have to be specially designed, which increases the cost of the system and may create ancillary storage and handling problems during manufacture. These spreaders are frequently combined with custom heat transfer devices in the design of heat control systems.
When custom heat transfer devices are used, the devices and their associated electronic components are typically assembled with clamps, nuts and screws, any one of which fastening methods involves a large number of small difficult to handle parts. This type of conventional assembly process requires several small parts to be meticulously handled with the aid of customized jigs, fixtures and other hand tools. This type of handling generally complicates the manufacturing process and makes it slower, more costly and inherently less reliable. Additionally, it can be anticipated that a number of completed circuits will be rejected for quality control reasons because leads become bent or misaligned due to vibration and handling.
Accordingly, what is needed in the art is a heat transfer device that can be associated with a circuit and the heat generating components on the circuit using a simple attachment method requiring the use of substantially fewer parts in the assembly process than prior art methods. The device should advantageously handle a number of heat generating components and should lend itself to being used in the manufacture of low profile systems. Such a device would be most advantageously employed if it could also function as a component in combination with other devices in a heat control system as well as a stand alone heat control device.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides a heat transfer device for cooling an electronic component mounted to a substrate. The present invention also provides for a method to cool electronic components by using the heat transfer device and a method to manufacture the heat transfer device. One embodiment of the heat transfer device comprises an elongated body having opposing first and second major surfaces and opposing first and second minor surfaces; a mounting recess extending along a length of the second minor surface; a first ledge extending from the first major surface and defining a first component mounting area of a first lateral dimension; and a second ledge extending from the second major surface and defining a second component mounting area of a second lateral dimension, the second dimension differing from the first dimension.
In broad scope, the present invention introduces a heat transfer device that can function either on a stand alone basis or as a component of a larger heat transfer system. In particular, the device has several favorable characteristics that provide a distinct advantage over prior art when used in low profile electronic systems. The device can be used alone as a heat transfer device to which heat generating components are attached, or it can be combined with other commercially available heat sinks to provide heat control for a larger number of devices. Because it can be used on a circuit in lieu of spreaders, it permits the design and manufacture of circuits using fewer parts, which provides a distinct cost advantage.
Included among the invention's various embodiments is a version of the device with the mounting recess configured to also serve as a cooling channel. Another embodiment provides for a channel extending along the length of the first minor surface, which channel is configured to dissipate heat and provide a receptacle for a spring clip to secure components to the device. Other aspects of the invention provide receptacles for spring clips to be used to secure components to the device. In one such aspect, a first auxiliary ledge extends from the first major surface to parallel the first ledge and define a spring clip receptacle for a spring clip to secure components to the device. In another version, the device has a second auxiliary ledge extending from the second major surface to parallel the second ledge and define a spring clip receptacle for a spring clip to secure components to the device.
A particularly advantageous iteration of the invention provides for pins that are press fit into the mounting recess, which pins are used to mount the device on a substrate by press fitting the pins into holes on the substrate. Another advantageous iteration of the device permits a heat sink to be releasably fastened to the first ledge or to the second ledge.
The present invention also provides a method for cooling an electronic component mounted to a substrate. When the heat transfer device is fastened to a substrate, other heat transfer devices can be combined with it in a modular system, which can be advantageously employed with low profile or compact electronic systems.
Also claimed is a method to manufacture the heat transfer device claimed herein. The claimed method calls for extruding the device, which extrusion can include any number of the various embodiments claimed. The fact that the extrusion can be cut to any length deemed necessary is a particularly attractive and desirable feature of the invention. It permits the device to be tailored to the size of the substrate on which it will be mounted as well as the number of components with which it will be combined.
The foregoing has outlined, rather broadly, preferred and alternative features of the pre
Lucent Technologies Inc
Thompson Gregory
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