Research On The Mechanism And Technology Of Nanosecond Ultraviolet Laser Micro-hole Machining Of Polydimethylsiloxane Film

Polydimethylsiloxane(PDMS)is a high molecular polymer material,which has been widely used in flexible electronics,microfluidics,MEMS,and biomedicine.Reasonable micro-holes structure can enrich the material properties of PDMS films.Among many methods for preparing micro-hole structure of PDMS film,laser processing has significant advantages such as non-contact,high precision,and high flexibility.Compared with lasers such as femtoseconds and picoseconds,nanosecond lasers have low cost,high stability and high stability.In addition,the ultraviolet light source can obtain a smaller focused spot than infrared,green light and other light sources,and the PDMS film has a higher absorption rate for it.Therefore,nanosecond ultraviolet laser was used to process the micro-hole structure of PDMS film in this study.However,the ubiquitous heat damage phenomenon during the processing restricts its industrial application.In order to realize the high-quality and high-efficiency processing of PDMS film micro-hole structure,this paper focused on the mechanism,process law,parameter optimization and application of PDMS film nanosecond ultraviolet laser micro-holes processing.The main research content includes the following three aspects:(1)Aiming at the problem of unknown reasons for the formation of micro-hole,the dominant mechanism of the reaction was obtained by analyzing the phenomenon of nanosecond ultraviolet laser ablation of PDMS film,and the relevant inferences were verified through preliminary experiments and the process of laser ablation of materials was further clarified.Based on the above theoretical basis,the transient thermal-stress coupling model of PDMS film laser micro-hole machining was established.The phase transition,temperature field and stress field information at each time and space node in the processing process were solved and analyzed,and the influence mechanism of thermal-stress behavior on the quality of micro-hole machining was obtained.(2)Aiming at the problem of unclear processing rules,the laser ablation threshold of PDMS film was obtained by extrapolation,which provides guidance for the parameter setting of single-factor process experiments.The environmental temperature was introduced into the experimental variables,and the influence of pulse energy,number of pulses,defocus,and environmental temperature on the quality of micro-hole processing was explored through single-factor experiments.Combined with the influence mechanism of micro-hole quality,the formation reasons of micro-hole geometrical morphology and surface morphology were explained to further verify the correctness of the above mechanism,and provide a process interval for the optimization of machining parameters.(3)Aiming at the problem of poor quality of micro-hole processing,through the process interval obtained from single-factor process experiments,a four-factor five-level orthogonal experiment was designed and carried out based on the combination of pulse energy,number of pulses,defocus,and environmental temperature.Through the range analysis method,the significance of the influence of each factor on the aperture,hole depth,taper and wrinkle zone was obtained,and the optimal micro-hole machining process parameters were obtained.In addition,a study on the enhancement of the tensile performance of the flexible device based on the optimized parameters was carried out.The results showed that the maximum tensile rate of the flexible electrode after optimization was increased from 13% to 43%.