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Modeling of laser drilled microhole profiles in carbon fiber composites in low fluence regime

A model describing laser microhole drilling processes in polymers has been developed, which can predict the drilling profiles of the microholes for several kinds of specific incident beam profiles. The report tries to answer how the peak fluence, the beam diameter (or beam shape), and the material parameters affect the hole shapes. The model not only provides the drilling hole profiles but also explains why hole drilling stops under certain circumstances, such as a stabilized or saturated drilling occurs, under this condition more shots applied to the process will not generate any further drilling effect. Thus high efficient laser processing can be predicted from the model, i.e. what are the best laser parameters for certain processed materials including material thickness. This model is suitable for most well defined beams and materials such as polymers, polyimide, polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), fiber reinforced composites or CFC, glass fiber composites, and some ceramics. This paper mainly concentrates on the modeling, while the comparison of the modeling and the experimental data will be discussed in the other paper to be published in the same volume of SPIE.