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.

The paper describes the Magneto-Optic Kerr (MOKE) Imaging technique for imaging magnetic response of soft magnetic materials at external magnetic field. This method can be applied for investigating domain wall formations and propagation, localizing magnetic failing sites, and analyzing hysteresis response of the films at varying magnetic field strengths. The paper describes some use cases of this technique for failure analysis in magnetic sensors, whereby in some cases delayering have been developed prior to imaging.