Evaluation of the environmental protection of photo BCB polymers (CycloteneTM 4000)

With the demand for higher interconnect density increasing, the ability of polymeric insulation to resist current flow and protect circuits from corrosion is becoming more and more important. BCB polymer is being used commercially on many high density devices which must function in non-hermetic environments. It was therefore of interest to quantify the change in resistance and leakage current (under temp-humidity-bias), of BCB encapsulated circuits by conducting surface insulation resistance (SIR) and triple track testing (TTT). SIR of all the Cyclotene samples ranged from 7.5×10⁸ to 8.8×10⁹ Ω. TTT reveals stable resistance of all samples past 500 hours. Leakage current measurements of ⩽4×10 ^-11 amperes were observed. The BCB samples show results equal to or better than the Dow Corning vulcanized rubber control, indicating excellent circuit protection capability