Results of a study to investigate the cracking of glass seals in a surface-mount integrated circuit package with ceramic covers are presented. Finite element analyses were combined with principles of fracture mechanics to estimate values of lead tip displacement (or applied force) at the onset of seal cracking. Such cracking provides points of entry for moisture, and otherwise degrades package reliability. Limiting values of lead tip displacement were estimated by three different approaches. The results obtained were in close agreement, and appear to be consistent with physical observations.

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