Reliability ground rules change at <50 μm pitch

Qualification of a new 40 μm pitch wire bonding process requires significant process improvements and evaluations demonstrating process capability and reliability. Recent changes in the morphology of the ball bond, required to achieve high yield manufacturing with the largest diameter wire possible at this pitch, have changed the failure mode for high quality bonds. With newly developed high-strength bonding wire long-term aging is a critical task. Choice of failure criteria and test requirements are critical to success. These must assure long-term reliability and must also reflect reality. Ultra-fine pitch bonding on probed bond pads can significantly effect process yields and intermetallic formation. Device designs that separate probe and wire bond placement within a rectangular bond pad are preferred.