Laser Ablation of Polymers

Laser ablation of polymers has been known since 1982 [8, 19]. Many aspects of polymer ablation and laser processing, in general, have been described by Bauerle [20]. More recently Lippert and Dickinson [21] reviewed in detail the chemical and spectroscopic aspects of polymer ablation and new directions. Many types of polymers can be laser machined, the most common ones being PI, PMMA, polyethylene (PE), polycarbonate (PC), poly(ethylene terephthalate) (PET) and poly-etheretherketone (PEEK). Other polymers include polytretrafluoroethylene (PTFE), S-U8 resist, other photoresists and acrylics. 

During the last decade, processing of polymers has become an important field of applied and fundamental research [48]. One of the most important fields is laser ablation involving various techniques and applications. Laser ablation is used as an analytical tool for MALDI (matrix-assisted laser de-sorption/ionization) [28, 29] and LIBS (laser-induced breakdown spectroscopy) [49] or as a preparative tool for PLD (pulsed laser deposition) of inorganic materials [37] and of synthetic polymer films [50, 51]. Another application is surface modification of polymers [52] if low fluences are applied, the polymer surface can be either chemically modified to improve adhesion 

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Laser ablation of polymer films has been extensively investigated, both for application to their surface modification and thin-film deposition and for elucidation of the mechanism [15]. Dopant-induced laser ablation of polymer films has also been investigated [16]. In this technique ablation is induced by excitation not of the target polymer film itself but of a small amount of the photosensitizer doped in the polymer film. When dye molecules are doped site-selectively into the nanoscale microdomain structures of diblock copolymer films, dopant-induced laser ablation is expected to create a change in the morphology of nanoscale structures on the polymer surface. 

As aforementioned, laser ablation of polymer films themselves and dopant-induced laser ablation of polymer films have been extensively investigated. The photochemical or photothermal mechanism has been discussed. The feature of the dopant-... 

After the first reports about laser ablation of polymers in 1982, various applications have been suggested. One of the most important applications of... 

Laser ablation of polymers has been studied with designed materials under two aspects ... 

In previous years studies on the photoablation of polymers for etching purposes have been few. Over the last twelve months however, this area of work has expanded enormously and may be an indication of its commercial fruition. A dynamic model has been proposed for the laser ablation of polymer systems which implicates the successive absorption of two or more photons causing population to higher electronic excited states . In this work the excitation time of laser pulses was stepped and indicated that short-lived radicals play an important role in ablation. The wavelength of the... 

Laser ablation of polymers was first reported by Srinivasan and Mayne-Banton [ 1 ] and Kawamura et al. [2] in 1982. Since then, numerous reviews on laser ablation of a large variety of polymers and the different proposed ablation mechanisms have been published [3-11]. There is still an ongoing discussion about the ablation mechanisms, for example, whether it is dominated by photothermal or photochemical processes. 

P.E. Dyer, Laser ablation of polymers in I.W. Boyd and R.B. Jackman (Eds.), Photochemical Processing of Electronic Materials, Academic Press Limited, London, 1992, pp. 360-385. 

A comparison of characteristic ablation parameters (see Table 9.6) reveals that the polymer containing triazene groups possesses a lower threshold fluence and a higher etch rate than the other two polymers and is, therefore, most appropriate for technical processes based on laser ablation of polymers. 

Creasy, W. R. and Breima, J. T., "Formation of High Mass Carbon Cluster Ions from Laser Ablation of Polymers and Thin Carbon Films," /. Chem. Phys., 92, 2269-2279,1990. 

For laser ablation of polymers, the key parameter is the laser fluence. Each combination of polymer material, laser wavelength, and pulse duration has a distinctive threshold fluence, below which no ablation takes place. The typical ablation depth vs. laser fluence is shown in Fig. 3. It plots the average ablation depth of poly(methyl methacrylate) at different fluences with a 193 nm excimer laser [4]. 

Taylor RS, Singleton DS, Paraskevopoulos G (1987) Effect of optical pulse duration on the XeCl laser ablation of polymers and biological tissues. Appl Phys Lett 50(25) 1779-1981... 

Creasy, W.R., Brenna, J.T. (1990) Formation of high mass carbon cluster ions from laser ablation of polymers and thin carbon films. Journal of Chemical Physics, 92, 2269-2279. 

This chapter is organized in five sections. The first reviews the various lasers used in laser micromachining and the principles of interaction of laser light with matter. The second section gives examples of laser ablation of polymers and their applications. Two other sections are devoted to surface modification and generative laser processes based on layered manufacturing. Finally, a number of other laser-based processes are presented, before concluding. 

Schmidt, H., Ihlemarm, (., Wolff-Rottke, B., Luther, K., and Troe, (. (1998) Ultraviolet laser ablation of polymers spot size, pulse duration, and plume... 

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