Membrane-based mechanical characterization of screen-printed inks: Deflection analysis of ink layers on polyimide membranes

Measurements of Young's modulus and residual stresses of screen-printed ink layers using a bulge test on coated polyimide-based membranes are proposed in this work. The applied bulge test monitors the deflection of membranes under pressure with interferometry. The obtained Young's modulus ranges from 6 to 8 GPa for a carbon blend-based ink and is around 12 GPa for a silver nanoparticle ink. These values are compared with standard nanoindentation and show good agreement. Besides, the residual stresses range from −4 to 8 MPa for the carbon blend-based ink, while the silver ink is measured around −10 MPa. The use of the membrane-based method underlines the influence of exact deposition and curing conditions on the ink film material properties. The impact of the substrate on the ink layer properties, such as the thickness and its uniformity, is discussed, especially with regard to the heat treatment of the membrane

Enhancing Partial Discharge Detection by Tuning Residual Stresses in Ultrathin CMOS-compatible Multilayer Membranes for Resonant Frequency Control

Partial Discharges (PD) are destructive events occurring in high-voltage equipment. [1,2] - Electrical discharge that occurs inside an insulating layer but does not cause full short-circuit - Is localised around defects in insulation material - Linked to 85% of assets failures as material deteriorates due to such discharges - Emits wide variety of signals among which a sound wave that is referred to as Acoustic Emission (AE) AE detection can be done using an ultrasound microphone that needs to be sensitive to the 70 kHz to 170 kHz range