Volume 21, Issue 5 (September 1993)
Influence of Substrate Deformations on the Thermal Fatigue Life of SMT Solder Joints
Previously published expressions based on life data for bulk solder are used in this paper to calculate the number of thermal cycles to failure of the solder joints of leadless chip carriers attached to various substrates. The devices used by Hall in thermal chamber cycling and power cycling are chosen for analysis. The values of deformations in terms of shear strain range and total mismatch are presented and compared. The fatigue lives of the solder joints are predicted based on the deformation data, the test conditions, and the Coffin-Manson expression. Attempts are made to correct some crucial differences in previous work or to fill in for missing information. The resulting predictions are explained according to the specific models used.