A glass in the CaO/MgO/Al2O3/SiO2 System for the rapid laser sealing of alumina

In the field of microelectronics housings made of corundum or sapphire are used, because they resist high mechanical stresses and can be used in extreme environments. For joining these components, sealing materials are necessary, which have a thermal expansion coefficient adapted to corundum or sapphire (8.2×10 −6K−1) and resist high temperature. This can be achieved by glass, which is crystallized during the joining process. However, the temperatures in conventional joining processes are not suitable for the encapsulation of temperature “sensitive components”. During a laser joining process only the joining zone is heated up for a short period of time and the components were not destroyed. For this process glasses from the system CaO/MgO/Al2O3/SiO2 were chosen and analyzed with respect to their sintering and crystallization behavior. The glasses could be sintered and crystallized by using the laser joining process. The crystallized glasses have a thermal expansion coefficient between 8.1×10 −6 K−1 and 9.3×10−6 K−1 and hence, show a good match for joining of corundum and sapphire.