Reliability Factors in Ceramic/Metal Joining

AbstractThis paper reviews the processing factors in joining ceramics to metals concerning the reliability. Thermal expansion mismatch has a great influence not only on the absolute value of strength but also on the reliability of joints. Large thermal stress increases the scatter of joint strength because of the presence of defects induced during joining process. One should insert an appropriate interlayer to relax the stress between a ceramic and a metal. Surface roughness also has some influence on the reliability. A roughly ground bond face leads large scatter in strength. Scratches must be removed before joining. Unjoined area reduces joint strength especially in solid-state joining. In brazing, the homogeneity in the braze layer should be also controlled carefully. A slight applied pressure during brazing can preserve the integrity of joints.