MANUFACTURE OF AN INTEGRATED CIRCUIT PACKAGE.

Abstract

Pseudoelasticity, shape-memory, and reverse shape-memory effects have been observed in the same wrought polycrystalline copper-zinc based ternary alloys. Reverse shape-memory involves movement of the material towards the direction of original strain upon application of heat when strain is applied at a temperature below the M//S or slightly above. Following deformation, the material is heated to a higher temperature range than is normally used to produce shape-memory effects, typically, between about 230 degree C and 550 degree C. This process occurs isothermally, and it involves decomposition into a bainitic phase. Alloys were rolled into thin strip, and fabricated into integrated circuit lead frames by photochemical etching. Multiple bonds were produced simultaneously between solder pads on a semiconductor chip and fingers extending from the frame member. The shape-memory process and reverse shape-memory effects were used to control movement of these fingers.