Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-10-01
2001-01-09
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C248S027100, C361S719000
Reexamination Certificate
active
06172873
ABSTRACT:
FIELD OF INVENTION
This invention relates to a device for securely mounting, stabilizing and retaining multiple electronic modules on a circuit board and, more specifically, to a mounting mechanism attachable to the circuit board which traps and holds the electronic modules on the circuit board and thus prevents movement of the electronic modules relative to the circuit board, insuring maintenance of circuit connections between the electronic modules and the circuit board.
BACKGROUND
Newer microprocessors, such as those used in personal computers, are being integrated, along with memory and other closely related circuits, into an integrated electronic module. Of necessity, as additional circuits are integrated into the electronic module, the size and mass of the module has increased to the point that it is desirable to edge mount the module to the circuit board in order to conserve space on the circuit board as well as to enhance cooling.
Increased usage of parcel shipping services rather than the traditional freight methods of the past for the delivery of the product to the customer has increased the impact and handling stresses on a computer. This is particularly so on unsupported electronic components which otherwise would rely only on their electrical connections for support and attachment.
While an increase in mass of circuit components is not an inherent problem to the operation of the computer, not only does the larger mass create a higher risk of breakage during shipment of the computer, but also the larger number of electronic circuits integrated into electronic modules creates significant operational heat that must be dissipated. The heat dissipation requires a significant additional mass of a heat sink and/or heat radiator, such as fins or pins, to be attached to the body of the electronic module.
Additionally, with the increase in microprocessor speed which has occurred in the recent past and the integration of the additional circuits along with the microprocessor into electronic modules, any heat generated with usage of electricity within the electronic module requires dissipation at a maximum rate in order to maintain the operating temperature of the electronic module within proper ranges. This typically is accomplished by attaching a heat sink to the electronic module to absorb the heat and to provide a large surface area to transfer the heat to the air circulated over the heat sink. This added mass of the heat sink exacerbates the attachment and retention problems created by shipping and handling of the computer.
It is not practical to increase the bonding surface area of the solder connections between the electronic module and the circuit board to provide adequate strength to insure adequate and stable attachment as well as circuit continuity.
OBJECTS OF THE INVENTION
It is an object of the invention to securely mount and retain electronic modules on a circuit board.
It is another object of the invention to reduce shipping and handling stresses on electronic modules and particularly their attachment points to the circuit boards.
It is another object to stabilize the electronic modules to resist acceleration and deceleration forces occurring during drops and handling.
It is a further object to accommodate substantial heat sinks associated with and attached to electronic modules whenever rigidifying the connection of the electronic modules with the circuit board.
SUMMARY OF THE INVENTION
Electronic modules are mounted on their edges to a circuit board, disposed projecting upwardly. The edge connection points or pads, soldered to the circuit board connection points or pads, hold the electronic module in the desired orientation relative to the circuit board. A pair of risers fabricated preferably of a low cost material, such as high strength plastic, is mounted on the circuit board to capture and stabilize the electronic module in its desired orientation. The risers may be fitted and attached to the circuit board and the electronic modules after the circuit board is populated.
A heat sink may be mounted on one of the large flat surfaces of the electronic modules, and extended between the module edges engaged by the risers. If desired, the heat sink may extend beyond one edge of the electronic module, such as the top edge to enhance heat dissipation.
The heat sink typically is an aluminum extrusion formed as a flat plate having fins extending from one face of the plate in order to dissipate heat to the surrounding air. The fins may be continuous or, preferably, may be spikes or pins formed by cutting the fins in a direction orthogonal to the plane of each fin, thereby leaving a larger member of upstanding shafts or pins, typically of square or rectangular cross-section.
Due to the thermal expansion and contraction of the electronic module as it heats and cools with use and with an intent to isolate the electronic module from significant externally induced forces and stresses on the electronic module, the heat sink may be attached to the electronic module using a heat conductive adhesive. The adhesive attaches the heat sink and the electric module while accommodating any mismatch of thermal expansion between the electronic module and the heat sink. This arrangement permits the heat sink, having been extruded, to have a retaining rail formed on a planar surface of the flat plate portion and then subsequently use to the rail as a retaining structure for engagement by the mounting device.
The mounting device, made up of risers attached to the circuit board and a bridge member, forms a three-sided frame which stabilizes and constrains the electronic module relative to the circuit board. The constraint of the risers is provided by the channels in the risers engaging the side edges and a small portion of the front and back surfaces of the electronic modules. The bridge is provided with a mating groove or surface that engages or mates with the rail on the heat sink surface opposite the surface supporting the heat dissipation pins. The retaining force exerted on the heat sink and thus the electronic module is supplied by the bridge in order to insure the heat sink and electronic module do not move or rotate relative to the circuit board.
The mounting and retention mechanism retains as well as stabilizes the electronic module in its preferred orientation relative to the circuit board and further helps to insure that electrical continuity between contacts on the circuit board and contacts on the electric module is maintained.
A better and more complete understanding of the invention may be garnered from the attached drawings and the following Detailed Description of the Drawings.
REFERENCES:
patent: 4002381 (1977-01-01), Wagner
patent: 4048669 (1977-09-01), Bowler
patent: 4503484 (1985-03-01), Moxon
patent: 4546407 (1985-10-01), Benenati
patent: 5642263 (1997-06-01), Lauruhn
patent: 5731956 (1998-03-01), Nocolici
patent: 5943218 (1999-08-01), Liu
patent: 5966289 (1999-10-01), Hastings
Davis David R.
Erickson Vernon
Schindler John
Gateway Inc.
Letson Laurence R.
Tolin Gerald
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