Abstract: A substrate for reducing electromagnetic emissions is provided. The substrate may include a plurality of ground layers, signal layers and power layers. All of the layers other than the ground layer are provided with a ground ring that may extend around the perimeter of the layer. The ground rings are electrically coupled together by ground stitching or vias that are randomly spaced. The random spacing of the ground stitching is based on the operating frequencies of the integrated circuit devices mounted on the substrate. Additional shielding may be provided by providing a cover assembly made of any conductive material that is coupled to the exposed ground rings on the uppermost and lowermost surfaces of the substrate. The cover assembly is coupled to the exposed ground rings in a randomized pattern. The device provides a virtual electrical ground cage in which the internal signal layers are totally enclosed, thereby reducing electromagnetic emissions.

Abstract: An electronic cartridge comprising a cartridge substrate, a package substrate, an integrated circuit, and an enclosure. The package substrate is mounted to the cartridge substrate. The integrated circuit is mounted to the package substrate. The enclosure encloses the integrated circuit, the package substrate and the cartridge substrate.

Abstract: Impacts to the case of a portable electronic unit including a display are dissipated by a plurality of thermoplastic elastomeric damping elements which isolate an internal frame unit, carrying the display and associated electronic components, from contact with the enclosure. Each damping element is provided with corresponding positioning structures within the case to ensure that the frame unit "floats" on protective shock absorbing material to provide three-dimensional support and damping of impacts incident from any direction. Damping elements may take the form of small caps of elastomeric material at spaced positions around the periphery of the frame unit. Electronic connections to the display screen are accomplished using flexible connectors to maintain the mechanical isolation of the display screen from the rest of the unit.