Electrostatic Force Microscopy Technique for Understanding Failures in Polyimide Insulation Barriers

Abstract Inductive coupling devices have emerged as superior alternatives to traditional optocouplers, offering improved performance, smaller size, and lower power consumption. However, these devices rely critically on a polyimide isolation barrier that can fail through high-voltage breakdown at its edges. We present a systematic study using electrostatic force microscopy to characterize charge injection and dissipation behavior in polyimide layers of varying thicknesses under different DC bias conditions. By correlating charge injection characteristics and dissipation times with layer thickness, we establish optimal barrier specifications to minimize product-level failures. This analysis provides crucial guidance for polyimide barrier design in inductive coupling applications.