Electronic assembly with electromagnetic shielding
A walled structure surrounds a primary interference-generating component. The walled structure is configured to confine or shield substantially the electromagnetic interference within the one or more metallic walls or within a cavity formed by the one or more metallic walls and a metallic side of the first enclosure portion. A primary electrically conductive pedestal projects above a base of the first enclosure portion within the one or more metallic walls to facilitate contact between the primary electrically conductive pedestal and the primary interference-generating component to provide a viable or possible low impedance path to electrical ground for a portion of the electromagnetic interference within the one or more metallic walls.
1. An electronic assembly comprising:
a circuit board having a conductive traces on a dielectric substrate;
an first enclosure portion configured to mate with a second enclosure portion to house the circuit board;
an antenna on or above the circuit board;
an electromagnetic interference shield comprising one or more metallic walls of the first enclosure portion, where the one or more metallic walls are electrically connected to one of said conductive traces on the circuit board;
a primary interference-generating component on a side of the circuit board facing a first enclosure portion, the one or more metallic walls surrounding the primary interference-generating component, the one or more metallic walls configured to confine or shield substantially the electromagnetic interference within the one or more metallic walls or within a cavity formed by the one or more metallic walls a metallic side of the first enclosure portion; and
a primary electrically conductive pedestal that projects above a base of the first enclosure portion within the one or more metallic walls to facilitate contact between the primary electrically conductive pedestal and the primary interference-generating component to provide a possible low impedance path to electrical ground for a portion of the electromagnetic interference confined within the one or more metallic walls.
2. The electronic assembly according to claim 1 wherein the antenna comprises a planar antenna that is on the circuit board and spaced apart from the one or more metallic walls.
3. The electronic assembly according to claim 1 further comprising
an electrically conductive adhesive or a resilient interface member is disposed between a top of the one or more metallic walls and an interfacing side of the circuit board to form an electrical connection and mechanical connection between the metallic wall and the conductive trace of the circuit board.
4. The electronic assembly according to claim 1 wherein the one or more metallic walls terminate in one or more projections that are spaced apart from each other along a perimeter and a top of the one or more metallic walls, each projection is configured to align or register with a recess, opening or a plated through-hole in the circuit board that corresponds in shape and size to the respective projection.
5. The electronic assembly according to claim 4 wherein said conductive trace comprises a foundation conductive trace as a metallic strip on the circuit board that corresponds to the perimeter of the one or more metallic walls of the first enclosure portion, wherein the one or more metallic walls are soldered to the foundation conductive trace by solder, or adhesively bonded to the foundation conductive trace by a conductive adhesive, or electrically connected to the foundation trace by a resilient interface member.
6. The electronic assembly according to claim 1 wherein the conductive trace comprises a foundation conductive trace as a conductive grid on the circuit board that is bounded by to a perimeter of the one or more metallic walls of the first enclosure portion, wherein the metallic walls are soldered to the foundation conductive trace by solder, or adhesively bonded to the conductive trace by a conductive adhesive, or electrically connected to the foundation trace by a resilient interface member.
7. The electronic assembly according to claim 1 wherein the first enclosure portion comprises an electrically conductive critical region below the antenna that provides a generally low impedance path to electrical ground for reduction of electromagnetic interference or coupling of electromagnetic interference between the antenna and other interference-generating components on the circuit board.
8. The electronic assembly according to claim 1 wherein a heat-generating component is located on the circuit board, the one or more metallic walls is configured to dissipate heat from the heat-generating component to an exterior of the enclosure via the first enclosure portion.
9. The electronic assembly according to claim 8 wherein the exterior of the enclosure is in thermal communication with an ambient air to dissipate thermal energy to the ambient air.
10. The electronic assembly according to claim 1 further comprising:
a heat-generating component on the circuit board,
an electrically conductive pedestal that projects above a base of the first enclosure portion within the one or more metallic walls to facilitate thermal communication between the heat-generating component and the first enclosure portion;
a resilient interface member disposed between the heat-generating component and an interfacing side or the pedestal of the first enclosure portion to form an electrical connection and thermal communication path between the first enclosure portion and the heat-generating component.
11. The electronic assembly according to claim 1 further comprising:
a secondary electrically conductive pedestal that projects above a base of the first enclosure portion outside the one or more metallic walls to contact a secondary interference-generating component to provide a low impedance path to the ground for the electromagnetic interference outside the one or more metallic walls.
12. The electronic assembly according to claim 11 further comprising:
a resilient interface member disposed to form an electrical and thermal communication path between the interference-generating component and the secondary electrically conductive pedestal of the first enclosure portion.
13. The electronic assembly according to claim 1 wherein the antenna is coupled to a wireless communications device.
14. The electronic assembly according to claim 1 wherein the interference-generating components comprise any of the following: a switching device that is configured operate at a radio frequency, at a microwave frequency, or at fundamental frequency with harmonics of the fundamental frequency that tend to produce electromagnetic noise or interference.
15. The electronic assembly according to claim 1 wherein the heat-generating components comprise any of the following electronic devices: a power switching device, a capacitor, or an electronic data processor.
16. The electronic assembly according to claim 1 further comprising:
a heat-generating component on the circuit board,
an electrically conductive pedestal that projects above a base of the first enclosure portion within the one or more metallic walls to facilitate thermal communication between the heat-generating component and the first enclosure portion;
an electrically and thermally conductive foam interface member disposed between the heat-generating component and an interfacing side or the pedestal of the first enclosure portion to form an electrical connection and thermal communication path between the first enclosure portion and the heat-generating component.
17. The electronic assembly according to claim 1 further comprising:
a secondary electrically conductive pedestal that projects above a base of the first enclosure portion outside the one or more metallic walls to contact a secondary interference-generating component to provide a low impedance path to the ground for the electromagnetic interference outside the one or more metallic walls.
18. The electronic assembly according to claim 17 further comprising:
a secondary electrically and thermally conductive foam interface member disposed to form an electrical and thermal communication path between the interference-generating component and the secondary electrically conductive pedestal of the first enclosure portion.