Accelerated life performance of moisture damaged plastic surface mount devices

A study in which three manufacturers´ devices were moisture preconditioned and subjected to a simulated assembly process using both thermal and chemical exposures is discussed. C-mode scanning acoustic microscopy (C-SAM) was used to fully characterize the progress of internal delaminations and/or cracks for all parts. Results show significant temperature-humidity-bias life performance degradation for devices preconditioned with the higher levels of moisture preconditioning followed by chemical exposures. Moisture preconditioned devices with no chemical exposures show little life performance degradation. It was found that the C-SAM result of false healing on the leadframe fingers was correlated to the first to fail. Unbiased autoclave testing was found to be the least effective test for evaluating the life performance of moisture damaged devices.<>