Hewlett-packard Development Company, L.p.

Hewlett-packard Company

Lowell Edward Kolb

Samuel Martin Babb

Paul Howard Mazurkiewicz

Kristina Lynn Mann

Brian F Davis

Marvin Wahlen

Jonathan P Mankin

David Johannes Pommerenke

Kenneth E Hall

An electrically continuous, grounded conformal EMI protective shield and methods for applying same directly to the surfaces of a printed circuit board. The EMI shield adheres and conforms to the surface of the components and printed wiring board. The shield takes the shape of the covered surfaces while adding little to the dimensions of the surfaces. The EMI shield includes low viscosity, high adherence conductive and dielectric coatings each of which can be applied in one or more layers. The dielectric coating is initially applied to selected locations of the printed circuit board so as to be interposed between the conductive coating and the printed circuit board, preventing the conductive coating from electrically contacting selected components and printed wiring board regions. A high viscosity, non-electrically-conductive filler material is applied to printed circuit board regions that have surfaces that are cavitatious and/or which have a highly variable slope.

Method for manufacturing a printed circuit board having conformal EMI shield

An electrically continuous, grounded conformal EMI protective shield and methods for applying same directly to the surfaces of a printed circuit board. The EMI shield adheres and conforms to the surface of the components and printed wiring board. The shield takes the shape of the covered surfaces while adding little to the dimensions of the surfaces. The EMI shield includes low viscosity, high adherence conductive and dielectric coatings each of which can be applied in one or more layers using conventional spray techniques. The conductive coating prevents substantially all electromagnetic emissions generated by the shielded components from emanating beyond the conformal coating. The dielectric coating is initially applied to selected locations of the printed circuit board so as to be interposed between the conductive coating and the printed circuit board, preventing the conductive coating from electrically contacting selected components and printed wiring board regions.

EMI shield that adheres to and conforms with printed circuit board surfaces

A decoupling circuit on a printed circuit board is disclosed. The decoupling circuit comprises an electrical filter circuit electrically connected between an interconnect post and a ground land of the printed circuit board. The ground land is connected to a ground plane in the printed circuit board. The electrical filter shunts conducted interfering signals received at the interconnect post to the ground plane. Components of the electrical filter circuit and ground plane form a first receiver loop in which induced interfering signals can be generated. The decoupling circuit also comprises a second receiver loop comprising a conductive coating of an EMI shield conformingly adhered to surfaces of the decoupling circuit, and a conductive path of the first receiver loop. The second receiver loop is adapted to have induced therein a signal having a direction and magnitude sufficient to cancel interfering signals induced in the first receiver loop.

Interference signal decoupling on a printed circuit board

An electrically continuous, grounded conformal EMI protective shield and methods for applying same directly to the surfaces of a printed circuit board. The EMI shield adheres and conforms to the surface of the components and printed wiring board. The shield takes the shape of the covered surfaces while adding little to the dimensions of the surfaces. The EMI shield includes low viscosity, high adherence conductive and dielectric coatings each of which can be applied in one or more layers using conventional spray techniques. The conductive coating prevents substantially all electromagnetic emissions generated by the shielded components from emanating beyond the conformal coating. The dielectric coating is initially applied to selected locations of the printed circuit board so as to be interposed between the conductive coating and the printed circuit board, preventing the conductive coating from electrically contacting selected components and printed wiring board regions. A high viscosity, non-electrically-conductive filler material is applied to printed circuit board regions that have surfaces that are cavitatious and/or which have a highly variable slope. The filler material can be used in conjunction with conformal EMI shield board level coating. The high viscosity, electrically non-conductive filler material substantially covers each cavity such that the covered cavity is inaccessible and that the covered region of the printed circuit board has a contiguous, contoured surface. A pre-manufactured non-electrically-conductive component cover can be mounted over a corresponding component and secured to the printed wiring board. The component cover and printed wiring board surround the component, forming a sealed enclosure. The component cover has a thin cross-section and an interior surface that follows closely the surface of the component. This minimizes the volume enclosed by the component cover. In addition, the exterior surface of the component cover has a low profile, and prevents the conformal EMI shield from physically contacting the covered component. Instead, the exterior surface of the component cover is coated with the EMI shield.

Board-level EMI shield that adheres to and conforms with printed circuit board component and board surfaces

An electrically continuous, grounded conformal EMI protective shield and methods for applying same directly to the surfaces of a printed circuit board. The EMI shield adheres and conforms to the surface of the components and printed wiring board. The shield takes the shape of the covered surfaces while adding little to the dimensions of the surfaces. The EMI shield includes low viscosity, high adherence conductive and dielectric coatings each of which can be applied in one or more layers using conventional spray techniques. The conductive coating prevents substantially all electromagnetic emissions generated by the shielded components from emanating beyond the conformal coating. The dielectric coating is initially applied to selected locations of the printed circuit board so as to be interposed between the conductive coating and the printed circuit board, preventing the conductive coating from electrically contacting selected components and printed wiring board regions. A high viscosity, non-electrically-conductive filler material is applied to printed circuit board regions that have surfaces that are cavitatious and/or which have a highly variable slope. The filler material can be used in conjunction with conformal EMI shield board level coating. The high viscosity, electrically non-conductive filler material substantially covers each cavity such that the covered cavity is inaccessible and that the covered region of the printed circuit board has a contiguous, contoured surface. A pre-manufactured non-electrically-conductive component cover can be mounted over a corresponding component and secured to the printed wiring board. The component cover and printed wiring board surround the component, forming a sealed enclosure. The component cover has a thin cross-section and an interior surface that follows closely the surface of the component. This minimizes the volume enclosed by the component cover. In addition, the exterior surface of the component cover has a low profile, and prevents the conformal EMI shield from physically contacting the covered component. Instead, the exterior surface of the component cover is coated with the EMI shield. This enables the covered component to be removed from the printed circuit board for repair, replacement or salvage without having to risk damage to the printed wiring board or component that may occur with the removal of a conformal EMI shield applied directly to the component.

Low profile non-electrically-conductive component cover for encasing circuit board components to prevent direct contact of a conformal EMI shield

Interference signal decoupling using a board-level EMI shield that adheres to and conforms with printed circuit board component and board surfaces

A site reference source acts as a programmable frequency source. The site reference source includes a symmetrical radiating unit. The symmetrical radiating unit includes a cylindrical shaped structure, a signal generator, a power source and an antenna. The signal generator is housed within the cylindrical shaped structure. The power source is also housed within the cylindrical shaped structure. The power source provides power to the signal generator. The antenna is external to the cylindrical shaped structure. The antenna is electrically connected to the signal generator housed within the cylindrical shaped structure. In order to radiate signals, the signal generator generates signals and transmits the signals through the cylindrical shaped structure to the antenna.

Traceable self-contained programmable frequency source for performing

The degree of variation in the normalized site attenuation of an RF test chamber may be reduced by adjusting the properties of the RF absorbers lining the walls of the RF test chamber such that for the frequencies of greatest variation the ground screen formed by the conductive floor of the chamber appears to be much greater than its actual finite size. This may be done by progressively reducing the degree of chamber wall absorption (for the frequencies of interest) for locations on the walls closer to the floor. The reduction begins at a height above the floor equal to the height of the device under test above the floor, and proceeds to some maximum reduction in absorption at the level of the floor. The reduction in absorption has the effect of making the ground screen appear to be much larger than it really is, and may be obtained either by spacing the absorbing tiles apart by increasing amounts nearer to the floor, or by using less absorptive tiles closer to the floor, or both.

Growing community of inventors

Loveland, CO, United States of America

Lowell Edward Kolb