Residual stress and warpage of AMB ceramic substrate studied by finite element simulations

Ceramic substrates with high heat dissipation performance are utilized in high power electronic devices. This study investigates the warpage deformation and residual stress originating during manufacturing of the active material brazing (AMB) ceramic substrate to provide important parameters for the substrate design and ensure good reliability. Finite elements were used to analyze the effects of ceramic, metal and solder thickness, ceramic substrate size and pressure on residual stress distribution and warpage deformation. Calculation results of thermal elastic and thermal elastic-plastic finite elements are compared. Plastic deformation during the welding process greatly affects calculation results accuracy. It is found that the maximum axial stress is concentrated on the ceramic side and axial residual stress is the main factor causing cracking of the ceramic substrate. The thickness of ceramic, metal and solder, along with the substrate size have significant effects on residual stress and warpage deformation, which both can be reduced by applying external pressure.