Comparative Compliance of J-Lead and Butt-Lead Designs for Surface Mounted Components

The long-term solder attachment reliability of leaded surface mounted (SM) devices is controlled in part by the lead compliance. Lead stiffness characterization is then an essential feature of any program aimed at optimized package design and/or surface mount inter- connection reliability evaluation. J-type and butt-type lead design are commonly used an a wide range of active SM components. Structural models have been developed for representative J-lead and butt-lead configurations. The effective flexural and torsional spring constants for each lead design follow from elastic strain energy deformation analysis of the structural models.