Hygrothermal aging of flip-chip assembled MOEMS

A flip-chip version of an optical MEMS (MOEMS) assembly is demonstrated in this work. A dummy MOEMS device is attached directly onto a traditional FR-4 board using a novel isotropic conductive adhesive (ICA) in order to minimize both fabrication costs and footprint of the assembly. The assembly solution passed in situ electrical testing successfully during exposure to 85% relative humidity for 840 hours at 85 °C and 1000 hours at 95 °C. Two tested variants of the novel ICA were shown to perform better than a commercial reference material. Failures were observed for samples with the reference material after long exposure times or cool-down. Cross sections were made for inspection of failure mechanisms.