Transient Liquid Phase Bonding Using AgSn-Alloys for Stress Reduced Sensor Mounting

In this work, a foil-based die attachment method using Transient Liquid Phase Bonding is presented. Electroplated multilayers made of Ag and Sn are manufactured. Thermocompression bonding is performed on different test specimens. The isothermal solidification during the bonding process at 250 °C results in a bonding layer which is stable up to 480 °C or more. Measurements of the shear strength showed values up to 75 MPa. The influence of the CTE mismatch between chip and substrate material is shown using optical deformation methods. The results of these measurements showed that a stable connection is formed, but CTE matching of the materials in the assembly is necessary. Finally, NTC chip thermistors were used to show and compare the influence on the output signal of a sensor element. A change of the relative resistance caused by thermo-mechanical deformation was observed on the samples.