<p>The effects of the dielectric curing temperature on the interfacial adhesion characteristics of the photosensitive polyimide (PSPI)/Cu redistribution layer for fan-out packages were systematically investigated using a four-point bending test. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to analyze the chemical properties of PSPI. The interfacial adhesion energy increased as the curing temperature increased from 350 to 375&#xa0;°C. This increase was associated with the progression of the ring-closing reaction accompanied by an increase in imide (C–N) bonding. However, when the curing temperature was further increased to 390&#xa0;°C, the interfacial adhesion energy decreased, which is attributed to the partial degradation of carbonyl (C=O) bonds under excessive curing conditions. These results indicate that optimizing the curing temperature is critical to achieving reliable PSPI/Cu interfacial adhesion in FOWLP RDL structures.</p> Graphical Abstract <p></p>