Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-04-23
2001-04-17
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C248S027100, C361S704000
Reexamination Certificate
active
06219248
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a heat sink mounting apparatus and, more specifically, to an apparatus for attaching a heat sink to a substrate and a method of attachment.
BACKGROUND OF THE INVENTION
Electronic circuit designers have traditionally been concerned about controlling the heat that builds up during circuit operation. Heat control is vital to prevent individual component failure as well as a consequent circuit failure caused by failed components. The preferred method to control component and circuit heat is to dissipate excess heat into the atmosphere before the temperatures rise to a level where damage can occur. Heat dissipation is usually accomplished by associating heat transfer devices, such as heat sinks, with the components to absorb the component heat and radiate excess heat into the surrounding atmosphere.
The problems associated with heat control have become more pronounced as low profile and compact electronic systems have become the preferred choice of customers. These low profile and compact systems typically have design parameters that make it difficult to find space for all the required electronic components on the substrate of a printed wiring or circuit board, much less the heat transfer devices such components require to prevent heat related damage. For example, the specifications for a certain electronic system may call for a printed wiring or circuit board of no more than 125 square inches with a component height that cannot exceed 1.24 inches. Within this limited space, approximately 1700 electronic components must be accommodated, as well as the associated heat transfer devices necessary to remove over 100 watts of heat generated by the components.
Compact electronic systems also present additional manufacturing challenges. Limited component space means that specialized tooling may be required to assemble the heat transfer devices and their related components to the substrate. If specialized tooling is required, such tooling may have to be specially fabricated with a corresponding increase in the total production cost. In addition to specialized tooling, the manufacturing process often requires that the components be put together off the regular assembly line as sub-assemblies. When subassemblies are manufactured off line, additional handling problems must be addressed. Frequently, device leads have been inadvertently bumped or bent out of position between the time the assembly was built and when it is to be inserted in the substrate. When this happens, the operator must manually keep adjusting the device leads without the aid of the fixtures and jigs. Other problems include slowing the line down to accommodate such interruptions and the logistics of keeping track of parts, assemblies and subassemblies during the manufacturing process.
A number of the problems discussed above occur because heat transfer devices and mounts for such devices are not generally available on the commercial market for use in low profile and compact electronic assemblies. In fact, very few of the commercially available heat transfer devices are suitable for heat control when a large number of electronic components are required to be located in a restricted space. Most of the commercially available heat transfer devices are designed to accommodate only one or two electronic components, which means that several such devices are required to control the heat generated by a single circuit. Several heat transfer devices may be used in electronic systems where space is not a factor, but such is not acceptable in compact or low profile systems where space is at a premium.
In many cases where space is at a premium, the electronic components are mounted on heat spreaders and the spreaders are mounted on the substrate or printed wiring board with threaded studs and nuts. These spreaders frequently must be custom made when low profile or compact systems are manufactured. Such spreaders are frequently associated or combined with commercially available heat sinks to complete a heat control system. The use of spreaders on printed wiring or circuit boards typically means more and smaller parts are required. This is because the devices are usually fastened to the spreader with clamps, screws and nuts. Then the spreader assembly must be attached to both the substrate, as well as to other heat diffusing devices, which generally slows down the manufacturing process. Other heat diffusing devices are required because the spreaders, by themselves, do not have enough surface area to be effective as a stand-alone heat dissipating devices. Spreaders generally must be combined with a customized heat plate to increase the surface area.
Accordingly, what is needed in the art is a device and method that can be used to mount heat transfer devices and the associated electronic components on a substrate. The device should advantageously handle both spreaders and other heat transfer devices and provide for a completed electrical connection between the electronic components and the underlying circuit. Specifically, such a device should lend itself to being used in the manufacture of compact and low profile electronic systems.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides, a heat sink mounting apparatus for use in coupling an electronic component substrate to a thermal transfer device. The present invention provides for a dielectric strip having a longitudinal axis and opposing first and second sides, with the second side abutting the substrate when the heat sink mounting apparatus is mounted on a substrate. The heat sink mounting apparatus has a series of resilient planar fingers that are disposed on, and extend approximately normal to, the first side of the strip, which fingers are configured to removably engage a thermal transfer device. Notches on the fingers releasably secure the thermal transfer device to the heat sink mounting apparatus.
The present invention broadly introduces a device that can be used to mount heat sinks, other heat transfer devices, and spreaders to an electronic substrate. Such a device can be used to particular advantage in the manufacture and assembly of low profile electronics. In a particular advantageous embodiment, the heat transfer device described in copending U.S. patent application Ser. No. 09/298,427, entitled “Heat Sink Attachment Apparatus and Method,” jointly assigned with the present invention and incorporated herein by reference can be used in combination with the invention to manufacture and assemble low profile electronics.
In one embodiment of the invention the device has a resilient latch finger extending approximately normal from the second side and configured to releasably secure the dielectric strip to a substrate. A further refinement calls for a pair of latch fingers on the second side, configured to cooperatively secure the dielectric strip to the substrate.
A particularly advantageous embodiment of the invention has a guide receptacle on the dielectric strip that is configured to direct the electrical leads on the electronic components mounted on the thermal transfer device to corresponding electrical connections on the substrate. In another alternative, a separate guide receptacle is provided for each electrical lead on the electronic component. In one embodiment a break-a-way is inscribed on the dielectric strip between the guide receptacle and the dielectric strip to permit removal of the guide receptacle when it is not needed. In one embodiment of the invention the dielectric strip has an orifice to receive a fastener to secure the dielectric strip to the substrate.
The present invention also provides for a method of manufacturing a heat sink mounting apparatus. One embodiment of the method calls for the formation of a dielectric strip having a longitudinal axis and opposing first and second sides configured so that the second side abuts a substrate when the heat sink mounting apparatus is mounted. Formed on the first side o
Phipps Martha V.
Werner Paul L.
Lucent Technologies - Inc.
Tolin Gerald
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