Abstract: An electronic circuit assembly having anti-tombstoning solder joints, including: a substrate 10 having at least one mounting pad 20 thereon; an SMD 30 having at least one termination 40; and at least one solder joint 50 connecting each termination 40 to its respective mounting pad 20. Each solder joint 50 is convex in shape, having a continuous and substantially circular arcuate outer profile 60 and covering substantially all of the mounting pad 20 and substantially all of a top portion 42 of each termination 40. Each mounting pad 20 has a predetermined length lp and each solder joint has a predetermined volume of solder selected such that a positive net anti-tombstoning moment is exerted upon the SMD 30 when at least one solder joint 50 is in a molten state.

Abstract: A method of manufacturing an electronic circuit assembly that includes a number of electrically interconnected flexible films, each flexible film having a flexible electrical wiring circuit. The electrical wiring circuits are interconnected between film layers and the film layers are adhered to a molded backing structure. A first flexible film is formed with a pattern of flexible electrical wiring circuits created on at least one surface thereof. The first flexible film has a passage that provides an electrical connection through the flexible film. A second flexible film is formed with a pattern of flexible electrical wiring circuits created on a least one surface thereof. The second flexible film has an electrical interconnect feature that connects with the electrical passage on the first film and electrically connects the first film with the second film. The first flexible film is overlaid juxtaposed the second flexible film so that the passage is aligned adjacent the electrical interconnect feature.

Abstract: There is disclosed herein a surface mount printed circuit board having a substrate, at least one surface mount device, at least two mounting pads per device, solder joints connecting the terminations of the device to their respective mounting pads, at least one rectangular lifter pad on the substrate amid the mounting pads, and a solder mass on each lifter pad in contact with the bottom surface of the device. The inner and outer extensions of the mounting pads, the size, number, and shape of the lifter pads, and the amounts of solder deposited on the mounting and lifter pads are designed such that the solder joint has preferably convex outer fillets, the device is maintained at a predetermined height above the mounting pads, the inner fillet angle is maintained above a predetermined minimum angle to increase solder joint crack initiation time, and the overall solder joint crack propagation length is increased.

Abstract: A method for joining a component to a substrate applies a base solder portion to the substrate and provides a standoff solder portion in the base solder portion. The standoff solder portion has a higher melting temperature than the base solder portion and a height which substantially corresponds to a desired standoff height between the component and the substrate. The component is positioned on the standoff solder portion and the base solder portion is melted under reflow conditions to form a solder joint between the component and the substrate. This joint substantially encapsulates the standoff solder portion, wherein the reflow conditions create a dendritic structure between the base solder portion and the standoff solder portion.

Abstract: A circuit board includes a substantially non-conductive substrate and first and second rigid sheets. The first sheet forms a grid pattern substantially encapsulated by the substrate, and a portion of the first sheet extends beyond a boundary of the substrate to form a first interconnection terminal. The second sheet is also substantially encapsulated by the substrate and has a portion which extends beyond the boundary of the substrate to form a second interconnection terminal. The second sheet acts as an electromagnetic interference shield, and also has a coefficient of thermal expansion less than a coefficient of thermal expansion of the substrate.

Abstract: There is disclosed herein an electronic component 10 having an integral heat spreader 16 specially designed to assist in laser soldering of the heat spreader to a solder pad 22 on a substrate 20. The component 10 has a top surface 30, a bottom surface 32 generally parallel to the top surface, and at least one perimeter outer surface 34 generally orthogonal to and between the top and bottom surfaces. The component 10 comprises: a circuit portion 12; at least one termination 14 connected to the circuit portion 12 and extending outward therefrom; a heat spreader 16 portion situated generally beneath and in thermal contact with the circuit portion 12; and a body portion 18 enclosing at least a top surface of the circuit portion 12 and a part of each termination 14 proximate the circuit portion 12. The heat spreader 16 defines at least part of the bottom surface 32 of the electronic component 10 and at least part of the at least one perimeter outer surface 34 of the electronic component 10.

Abstract: A method of supporting an electrical circuit on an electrically insulative base substrate comprises embossing a first circuit pattern on the substrate, and plating or etching a second circuit pattern over the first circuit pattern such that the first and second circuit patterns are in physical contact with each other for electrical communication therebetween. Plated through-holes are provided for facilitating support of a twisted pair of electrical conductors on a base substrate.

Abstract: Method of surface mounting an electronic component to a bonding pad on one side of a supporting insulating board carrying a planar printed circuit thereon, the pad being connected to one or more conductors on the board by use of solder material subject to one or more gas trapping through-hole vias, comprising: (a) creating at least one vent channel below the top plane of the printed circuit and extending from a location at or closely adjacent to one of said vias to a location essentially near a periphery of solder material to be placed thereover; (b) planting a deposit of solder material between the component and pad; (c) bringing the component, solder material and pad together to form an assembly; and (d) heating the assembly to momentarily reflow the solder material in place without shifting, skewing, or tilting of the component, any trapped air in said one vias being allowed to expand and migrate away through the channel to at least the periphery of the pad.

Abstract: A footprint, and method for forming the footprint, of the type for mounting a surface mount component having a heatsink which defines a first registration edge thereon. The substrate pad is positioned on the substrate for registrated engagement with the heatsink. The substrate pad has an area substantially larger than the area of the heatsink to improve the dissipation of thermal energy. The substrate pad includes notches for defining registration edges which are juxtaposed with corresponding registration edges on the heatsink when the electronic component is in proper alignment with the substrate pad. Surface tension forces produced by melting solder interposed between the heatsink and the substrate pad act upon the registration edges to maintain proper alignment of the component with the substrate pad.

Abstract: A method for improving the reliability of solder joints is disclosed for use in reflow soldering. In the method, a predetermined amount of solder is applied to at least two solder pads on a circuit board and a component having at least two terminals is fixed in relation to the solder pads. The solder is melted so that the component floats to a predetermined height above the solder pads and, when solidified, the solder fillet formed at each terminal holds the component a predetermined height above the circuit board and forms a convex shape.