Interfacial Compatibility of Polymer-based Structures in Electronics

Interfacial compatibility of dissimilar materials was investigated to achieve a better understanding of interfacial adhesion in metal/polymer/metal systems. Surface modifications of polymers were applied to improve the adhesion. The modified surfaces were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements accompanied by surface free energy evaluations. The pull-off test was employed to assess the interfacial adhesion strength. Further, to determine the controlling adhesion mechanism, the fracture surfaces exposed in the pull-off test were examined by microscopy. To achieve modification of certain bulk properties of one of the evaluated polymers (SU8 epoxy resin), new star-shaped oligomers were synthesised and reactively blended with it. Oligomers were characterised by H and C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). Films of the blends were spin coated on a silicon wafer for characterisation of the refractive index and a novel non-destructive method was developed to measure selected thermal properties of the films. The information concerning interfacial compatibility obtained in this work is of great practical as well as theoretical importance.