Predictions and measurements of interfacial adhesion among encapsulated thin films of flexible devices

This study employed the four-point bending test (4-PBT) to measure the interfacial strength of pressure-sensitive adhesive (PSA)/SiN passivation stacked thin films. Finite element analysis (FEA) is combined with the J integral approach and the modified virtual crack closure technique to validate the results of 4-PBT. The FEA simulation results verify the measurement results. The stress status and energy release rate of the delaminated tip are also determined at different elevations of stacked thin films of 4-PBT specimens adjacent to the PSA/SiN interface. The crack in the PSA parallel to the foregoing interface with a slight span occurs on the fractured interface. This behavior is confirmed by observing the scanning electron micrographs of the specimens after 4-PBT. •Adhesion of pressure-sensitive adhesive (PSA)/SiN stacked thin films is investigated.•Four-point bending test is used to measure interfacial strength of PSA/SiN.•Validation is achieved by J integral and modified virtual crack closure approaches.•Results show that the crack in PSA film has a slight distance parallel to bonded interface.•Stress at crack tip of stacked films is estimated by using interfacial fracture mechanics.