IPC-WP-028 white paper provides guidance on obtaining objective evidence for validating the acceptability of bubbles in conformal coatings. It focuses on a failure mode where bubbles in coatings could activate a microclimate involving condensation of humidity inside the bubbles resulting in an increase of the local humidity load to a critical level, thus generating electrochemical migration failures. IPC-WP-028 white paper is referenced in J-STD-001J.