Novel packaging with rematable spring interconnect chips for MCM

Abstract

A novel packaging approach has been demonstrated for circuits connected with flexible microsprings. The approach is based on silicon micromachined features and results in a highly accurate and low cost packaging solution. The micromachined features were processed into silicon with an anisotropic wet etch forming inverted pyramidal micro-pits. The pits are integrated into the chips along with arrays of flexible and compliant interconnects arranged in a daisy chain arrays on 180 mum pitch. Packages based on two chips with matching set of pits have been assembled and characterized. First level reliability tests have been performed in 0degC-100degC temperature cycling, 85/85 temperature humidity bias and high-current soak. Multiple ldquorematingrdquo; tests were also carried out as the packages were taken apart and reassembled together. The ldquopit and springrdquo integration is expected to equally address not only the performance and functionality of the completed package but also its reliability and cost.