Compliance metrics for the inclined gull-wing, spider J-bend, and spider gull-wing lead designs for surface mount components

A compliance evaluation has been performed for a representative gull-wing lead for various lead inclination angles. The lead compliance metrics for a commercial TC (thermocompression)-bonded spider J-bend wire-lead have been parametrically evaluated over a wide range of typical lead heights. As the overall lead height is reduced from 185 mil to 135 mil, the corresponding diagonal lead stiffness increases to nominally 2.3 times the value for the tallest lead configuration. Comparative compliance evaluation has been performed for the spider J-bend wire-lead and a commercial S-bend clip-lead with rectangular cross-section. The diagonal spring constants for the 185-mil and 135-mil tall spider J-leads are respectively comparable to and nominally double the diagonal lead stiffness for the 153-mil tall S-lead. Depending on the SM (surface mount) interconnection reliability and PCB (printed circuit board) assembly requirements, the TC-bonded spider J-bend wire-leads can provide a design alternative to relatively high-compliance soldered clip-leads. The diagonal stiffness of TC-bonded and clip-type lead designs can be tailored using lead compliance analysis to optimize the contour, dimensions, and material.<
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