Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-04-20
2001-06-05
Gaffin, Jeffrey (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S818000, C361S824000, C361S807000, C361S808000, C361S809000, C361S810000, C174S034000, C174S034000
Reexamination Certificate
active
06243274
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates generally to shields for shielding selected electronic components and electronic sub-assemblies mounted on a printed wiring board assembly from electromagnetic interference (EMI) and/or from radio frequency interference (RFI). More particularly, the present invention relates to shields which provide ready access to shielded components for servicing.
2. Description of the Invention Background
Conventional EMI/RFI shielding systems use a number of individual electrically conductive shields constructed as containers which have sidewalls merging with an integral upper surface. An open-ended lower surface of each container is positioned on a printed wiring board assembly to enclose an electronic component or sub-assembly which is to be shielded. The open-ended surface is fixedly attached to the wiring board assembly, usually by soldering. Each individual container is connected to ground potential either by connection to a ground bus designed to intercept the solder area covered by the open-ended container surface, or by providing a common ground connection to all shields subsequent to soldering the open-ended container surfaces to the wiring board assembly. Frequently, the entire wiring board assembly is protected by an outer shield or housing against environmental influences such as, for example, dust, moisture, or intense light.
When access is required to electronic components shielded by such conventional container-shaped shields, for example, for testing or servicing purposes, individual shields must be removed by breaking the soldered connection between the open-ended surfaces and the wiring board. This procedure is time-consuming and frequently results in damage to the wiring board. Efficient troubleshooting is hindered since a technician will feel compelled to make an “educated guess” as to which shield to remove first and damage to the wiring board may be severe so as to preclude re-use of the wiring board. Thus, while “integral-container shields” provide desired EMI/RFI shielding of electronic components mounted on a printed wiring board, such prior art shields pose significant disadvantages when access to shielded components or sub-assemblies is required.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a plurality of EMI/RFI shields for shielding selected electronic components disposed on a printed wiring board wherein all shielded components are readily accessible for servicing without damage to the printed wiring board.
It is another object of the present invention to provide a plurality of EMI/RFI shields for shielding selected electronic components disposed on a printed wiring board wherein the plurality of shields have a common height dimension.
It is a further object of the present invention to provide a plurality of EMI/RFI shields for shielding selected electronic components disposed on a printed wiring board wherein the plurality of shields are formed of open-ended conductive casings having sidewalls of a common height dimension.
It is a still further object of the present invention to provide a plurality of EMI/RFI shields for shielding selected electronic components disposed on a printed wiring board wherein a compliant conductive member provides a common and removable cover for upper ends of open-ended conductive casings.
The foregoing and other objects and advantages of the present invention are achieved in the construction of a plurality of EMI/RFI shields for shielding each one of a plurality of selected electronic components and of selected electronic sub-assemblies disposed on a printed wiring board assembly. The shields are constructed as open-ended electrically conductive casings which have sidewalls of a common height dimension extending between lower ends and upper ends of the casings. The lower ends of the casings are fixedly attached on the printed wiring board assembly such that each shield surrounds selected electronic components and selected electronic sub-assemblies. A compliant electrically conductive member has lower and upper surfaces. The lower surface of the compliant member is disposed in common over the upper ends of the casings. An electrically conductive housing is positioned over the upper surface of the compliant member. A surface of the housing provides compression of the compliant member such that electrical contact is maintained between the housing and the upper ends of the casings. An electrically conductive base plate is spaced from the wiring board assembly. The base plate is connected to an electrical ground potential. The housing is removably attached to the base plate. When the housing is attached to the base plate, the plurality of shields are operative. When the housing is removed from the base plate and the compliant member is removed from the upper ends of the casings, access to the selected electronic components and to the selected electronic sub-assemblies is provided.
REFERENCES:
patent: 4357062 (1982-11-01), Everrett
patent: 4717990 (1988-01-01), Tugcu
patent: 4977483 (1990-12-01), Perretta
patent: 5596487 (1997-01-01), Castaneda et al.
patent: 5633786 (1997-05-01), Matuszewski et al.
patent: 5812374 (1998-09-01), Shuff
patent: 5847317 (1998-12-01), Phelps
patent: 5917165 (1999-06-01), Platt et al.
patent: 6058024 (2000-05-01), Lyford
patent: 62-187056 (1987-07-01), None
patent: 03311589 (1991-10-01), None
Dinh Tuan
Gaffin Jeffrey
Harris Beach LLP
Redcom Laboratories Inc.
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