Developing a High Density Pt/Alumina Hermetic Feedthrough

Abstract

I would like to offer my special thank Ross Hrubiak for his limitless help during high temperature X-ray synchrotron experiments. We worked together for more than 16 hours every day. During that time, however Ross taught me all aspects about the synchrotron. I couldn't imagine synchrotron study without him. v I would also want to offer my special thanks to Ali Hadjikhani for his help in different aspects of this project. Ali helped me with sample preparation and FIB analysis of the sample.He was also available whenever I needed for discussion. He was always ready to help beyond his limit at any hour of the day. Seven platinum powders with different particle sizes were used to develop different conductive cofire inks to control the densification mismatch between platinum and alumina.Firing profile (ramp rate, burn-out and holding times) and firing atmosphere and concentrations (hydrogen (wet/dry), air, neutral, vacuum) were also optimized. Platinum and alumina exhibit the alloy formation reaction in a reduced atmosphere. Formation of any compound can increase the bonding of the metal/ceramic interface, resulting in enhanced hermeticity. The alumina dissolves into the platinum ink and is redeposited as a surface coating. This was observed on both cofired samples and pure platinum thin films coated on a 99.6 Wt% alumina and fired at 1550 °C. Different mechanisms are proposed to describe this behavior based on the size of the platinum particle.