Ultra-miniature electrical contacts and method of manufacture

Abstract

Ultra-miniature electrical contacts are provided with the strength and resilience necessary to give stable low resistance connection, to minute areas of a device, such as a thousand or so closely spaced surface pads of an integrated circuit. Each contact is initially formed on a substrate as a thin, narrow elongated flat body comprised of selectively deposited layers of metal. Depending on the final configuration desired for the contact, the metal of one metal layer has a coefficient of thermal expansion such as chromium (Cr), and the metal of another layer has a coefficient of thermal expansion such as copper (Cu). Each contact is permanently formed (by differential expansion of the metal layers when heated) into a three-dimensional structure and is then made “robust” by a covering of a specialized stiffening metal plating which adds substantial strength to the contact. This also makes the contact “springy” and enables the contact to be deformed substantially without permanent deformation or “set”. Such ultra-miniature contacts are made using photolithography and techniques for deposition of metals and other materials onto a substrate, as commonly used in the semiconductor industry.