Ribbon Wire Versus Round Wire Reliability for Hybrid Microcircuits

In an effort to create a more reliable bond interface in hybrid microcircuits, a study was launched to evaluate the relative bond strengths of round wire and ribbon wire of comparable cross section, and to determine which is inherently more reliable after thermal degradation. This correspondence presents a comparative bonding reliability study of aluminum ribbon wire versus round wire, and gold ribbon wire versus round wire in hybrid microcircuits. The wires were ultrasonically bonded to thick film gold, thin film aluminum, thin film chromium-gold, and thin film molybdenumgold. Results showed that ribbon wire was superior to round wire and, that after 1000 hours of high temperature storage, aluminum round wire averaged 91% bond degradation on all types of substrates, while gold ribbon wire averaged 57% degradation. The average degradation of the wires on all of the substrate types is shown below in summarized form.