Enhanced bonding strength of Al2O3/AlN ceramics joined via glass frit with gradient thermal expansion coefficient

Ceramics joining has been widely applied in MEMS sensors, microwave and imaging devices as well as other ceramic packaging applications to fabricate multifunctional ceramic components. In this study, a glass frit with gradient thermal expansion coefficient (TEC) has been applied as the bonding material to join the ceramic of Al2O3 and AlN. This glass frit consists of two types of glasses with different TEC. The Al2O3 and AlN ceramics have been successfully joined with this glass frit in muffle furnace at 850 degrees C for 1 h. The bonding strength of Al2O3/AlN ceramic joined via this glass frit exceeds 40 MPa without any cracks in the joining interface, which is much superior compared with that of conventional glass frit bonding. Our work demonstrates that the gradient-TEC glass frit bonding is an effective method to join different types of ceramics.