Material Behaviour and Influence of Ceramics for Application in a Sensor Housing under High Temperature Load

This paper presents a suitable material combination for sensor housings for temperatures up to 1000 deg C. The focus is on the combination of different ceramic materials in the assembly. The thermal expansion coefficients must be matched to each other. The sensor housing, the carrier substrate and the electrical conductor paths must also perform reliably in the high-temperature range. The connection between the housing cap and substrate is made with a high-temperature glass solder. The housing and substrate connection is thermally cycled between 200 deg C and 1000 deg C and tested for shear strength. The results are compared to simulation. Furthermore, the connection between glass solder and sapphire is verified by metallographic cross-sections. Also, X-ray diffraction is used to determine the joint quality. The CTGS (Ca3TaGa3Si2O14) sensor element is bonded with glass solder as well. The two-sided mounting of the sensor will lead to mechanical stresses in the sensor material. Therefore, the displacement of the sensor element in the ceramic spacer under temperature load has to be monitored using optical measurement technology. The hardness of the CTGS sensor material is determined by hardness testing according to Vickers. The resistance to crack propagation is calculated from these tests. The mechanical temperature-dependent material parameters are additionally entered into a FE-simulation in order to verify the simulative alignment of the experiments. As a result, temperature-dependent material properties and a simulation model of the sensor package up to 1000 deg C are available. The temperature sensor based on the housed BAW resonator was already functionally tested.