Integrity of ceramic packages upon liquid nitrogen cycling

Abstract

The integrity of two types of test package (A and B) during cycling between 30°C and liquid nitrogen temperature (-196°C) is discussed. Type-A packages had polyimide-insulated chips and were characterized by higher thermal shear strain amplitudes (≤3.3%) than type-B packages, which contained quartz-insulated chips. For either type of packages, the chips were joined to the metallized ceramic substrate using the C4 solder (Pb-Sn) technology. Solder lifetime modeling and the solder fracture/cracking mechanism are discussed. No sign of fracture or delamination of the chip insulation was observed for either package type. The important features and conclusions of the study are summarized. The results indicate the potential of the packages for liquid nitrogen operation.