Abstract: An exemplary printed circuit board preform (20) includes at least two printed circuit board units (211), at least one boundary (201, 202) formed on the junction of the at least two printed circuit board units, and at least one conductor (206, 208) configured on a surface of the printed circuit board preform and crossing the at least one boundary of the at least two printed circuit board units.

Abstract: A printed circuit board defines a groove used to engage with an electronic element. The groove defines a plurality of side walls. The PCB further defines a plurality of via holes at junctions between each two neighboring side walls. The via holes are communicate with the groove and have a C-shaped section. When the electronic element is received in the groove, the electronic element snugly engages with the plurality of side walls of the groove.

Abstract: A circuit board includes four positioning pads placed on a surface of the circuit board, four positioning holes corresponding to the positioning pads, respectively, and a solder mask placed on the surface around the periphery of the positioning pads. An arc-shaped recess is defined at a side of each positioning pad near the corresponding positioning hole and the space between the edges of the positioning pad and the positioning hole ranges from 0.2 mm to 0.5 mm.

Abstract: A printed circuit board includes a substrate including through holes, pad portions arranged on surfaces of the substrate, and insulating areas. Each of the pad portions includes a first pad surrounding a corresponding through hole and a second pad. Each of the insulating areas is between each of the first pads and each of the second pads to electrically insulate each of the first pads and each of the second pads from each other. Attachment or removal of conductive layers to or from the insulating areas allows electrical connection or disconnection between the first pads and the second pads.

Abstract: A printed circuit board (PCB) includes a substrate, a plurality of copper foils formed on at least one surface of the substrate, a plurality of through holes extending through the substrate arranged in a rectangular array, and a plurality of blocking wall. Inner walls of the plurality of through holes are coated with the plurality of copper foils. The plurality of blocking walls project from the plurality of copper foils and surround the plurality of through holes to prevent solder from overflowing into the plurality of through holes when the PCB goes through a wave soldering procedure.

Abstract: An exemplary printed circuit board preform (20) includes at least two printed circuit board units (211), at least one boundary (201, 202) formed on the junction of the at least two printed circuit board units, and at least one conductor (206, 208) configured on a surface of the printed circuit board preform and crossing the at least one boundary of the at least two printed circuit board units.

Abstract: A circuit board includes four positioning pads placed on a surface of the circuit board, four positioning holes corresponding to the positioning pads, respectively, and a solder mask placed on the surface around the periphery of the positioning pads. An arc-shaped recess is defined at a side of each positioning pad near the corresponding positioning hole and the space between the edges of the positioning pad and the positioning hole ranges from 0.2 mm to 0.5 mm.