Polymers for KrF 248 nm Nanosecond Laser Micromachining

Abstract

This thesis starts, in Chapter 1, with an introduction to the krypton fluoride (KrF) 248 nm nanosecond laser micromachining. Chapter 2 covers preliminary research into the laser micromachining of eleven different kinds of commercial plastic films with different chemical structures and thermal properties. Chapters 3 and 4 discuss the synthesis and characterisation of chromophore functionalised poly(methyl methacrylate) and polyurethanes. The hypothesis for this section is based on the idea that incorporating a photosensitive group into a polymer’s main chains will enhance the laser-polymer interaction. The laser micromachining result proves that both the etch rate and the ablation area quality (as studied by Dektak® and SEM images) can be enhanced by modifying the polymers with a chromophore by comparing them with a corresponding control polymer. Besides insulating polymers, Chapter 5 aims to explore laser micromachining of conductive polyanilines with different dopants. Chapter 6 focuses on the laser micromachining of hybrid materials of polyaniline and polyurethane. In addition to the photochemical ablation mechanism, other researches have also demonstrated that the gaseous product generated during the decomposition process would enhance the laser micromachining result by blowing the debris away. Using this concept, Chapter 7 presents the synthesis and characterisation of two kinds of polyimide with a carbonyl group which could decompose into carbon dioxide during the ablation process and thus enhance the laser micromachining performance. Lastly, Chapter 8 presents laser micromachining studies of the perfluorocyclobutane polymer which display typical fluoropolymer thermal and chemical properties.