Bent Lead Design for Surface-Mounted Module
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Due to differences in thermal expansion between ceramic substrates and epoxy glass cards, if a module with area array pins is soldered to a card, the stress on the solder joints increases as the size of the module increases. The stress on the solder joints can be decreased by bending the pins to provide a foot. The pins in each quadrant are bent in a different direction. Each pin is bent: a) so that there is a 45-degree angle between the feet and the sides of the module, in the plane of the module; b) each two diagonal quadrants has pins bent in opposite directions; and c) the foot of pins in the quadrants next to each other are perpendicular to each other. This arrangement maximizes the moment of inertia in the principal bending planes of the pins.