[Paste deposition and chip bonding process development]. IBM, Endicott tenth quarterly report

The scope of Endicott activity during this quarter includes: paste deposition process development and chip bonding process development. It was discovered that small voids exist in the photobumps. These are typically at the base of the bump and are believed to have always been present. Although the reliability test results have been positive and no failure is attributed to voids, the process development work during the last quarter has focused on understanding how these form and how to reduce them. High feed pressure, slow nozzle speed and lower viscosity reduce void formation. Nozzle design changes have been identified. One change will increase the shearing of the paste during feed, thus reducing the viscosity, a second change will allow higher feed pressures. Chip bonding process development has focused on correlating bonding results between the IBM in-house chip bonder made by Research Devices, Inc. and the Universal development bond tool. Two variables have been identified that correlate with poor bond results. The report describes more detail of the activity during the tenth quarter for paste deposition and chip bonding in each of these areas