Electromagnetic shielding structures for selectively shielding components on a substrate
Electronic components on a substrate may be shielded using electromagnetic shielding structures. Insulating materials may be used to provide structural support and to help prevent electrical shorting between conductive materials and the components. The shielding structures may include compartments formed using metal fences that surround selected components or by injection molding plastic. The shielding structures may be formed using metal foil wrapped over the components and the substrate. Electronic components may be tested using test posts or traces to identify components that are faulty. The test posts or traces may be deposited on the substrate and may be used to convey test signals between test equipment and the components. After successful testing, the test posts may be permanently shielded. Alternatively, temporary shielding structures may be used to allow testing of individual components before an electronic device is fully assembled.
1. A printed circuit board, comprising:
a substrate;
an electronic component mounted to the substrate;
an electromagnetic shielding structure formed from metal foil wrapped over at least the electronic component, wherein the metal foil is wrapped around the electronic component and the substrate, wherein the substrate includes a top surface, a bottom surface, and a plurality of side walls, wherein the metal foil covers only the top surface of the substrate and the plurality of side walls, and wherein the metal foil curves directly over the electronic component; and
a spacer structure interposed between the electronic component and the metal foil, wherein the metal foil has first and second opposing surfaces, wherein the first surface is positioned above the substrate, and wherein the spacer structure contacts only a portion of the first surface.
2. The printed circuit board defined in claim 1 wherein the substrate includes a conductive ground plane and wherein the metal foil is coupled to the conductive ground plane at each side wall of the plurality of side walls.
3. The printed circuit board defined in claim 2 wherein the metal foil is attached to the conductive ground plane using solder.
4. The printed circuit board defined in claim 1 wherein the metal foil has a top surface and a bottom surface, the printed circuit board further comprising:
an insulating layer attached to the bottom surface of the metal foil.
5. The printed circuit board defined in claim 4 further comprising:
an additional insulating layer attached to the top surface of the metal foil.
6. The printed circuit board defined in claim 1 wherein the substrate includes a conductive ground plane, the printed circuit board further comprising:
at least one metal trace on the substrate, wherein the metal foil is coupled to the conductive ground plane through the metal trace.
7. Apparatus, comprising:
a substrate having opposing top and bottom surfaces;
first and second electrical components mounted on the top surface of the substrate;
a third electrical component mounted on the bottom surface of the substrate;
a metal foil that is wrapped around the substrate and encloses the first, second, and third electrical components, wherein the metal foil has a non-planar surface that directly overlaps the first, second, and third electrical components; and
an insulating spacer block that is interposed between the first electrical component and the metal foil, wherein the second electrical component and the insulating spacer block are non-overlapping.
8. The apparatus defined in claim 7 wherein the metal foil has first and second opposing surfaces that are each covered by an insulating layer.