Study On Improvement Of Machining Quality Of Surface Machined By Laser

In this paper，the excimer laser direct-writing ablation is used to fabricate themicrostructure on the substrate. The mechanism of excimer laser etching polymer isexperimentally investigated using Raman spectroscopy, AFM, and3-D surfaceanalyzer. The process of excimer laser micromachining is researched in detail andthe etched surfaces are improved.The physical and chemical models of excimer laser etching polymers and theirmechanism are summarized. The chemical structural changes of PMMA and PS afteretching are analyzed by Raman spectroscopy and Infrared spectrum. The fabricationof microfluidic chip containing micropillars was described. The geometricdeformation of micropillars in microfluidic chip on the PI and PMMA substrates wascaused by cumulative heat during laser ablation. Analysis of the cumulative heateffect of PI （polyimide） and PMMA was done （polymethyl methacrylate） whenablated using a KrF excimer laser for microfluidic. We researched the variation ofmicropillars’ geometric deformation on the different fluence and the number of laserpulses according to experimental observations.This paper presents an effective and low-cost method for fabricatingmicrofluidic chip based on excimer laser direct-writing ablation and replica molding.It is based on a newly excimer laser micromachining technique that can accuratelymachine microfluidic chip microstructure with smooth surface profile. Thecorrelation between the process parameters （The translational speed of workingplatform and the laser fluence） and the micromachining quality （the depth andsurface of the microchannel） is investigated. The profile accuracy and surfaceroughness of the produced microfluidic chip at each stage have been measured andmonitored. The average upper surface profile accuracy is better than2μm andaverage surface roughness is less than20nm. Experimental data show thecontrollability and accuracy of this micromachining process. Finally, anexperimental investigation has been performed on flow characteristics and pressuredrop of water in two different roughness rectangle microchannels. ITO electrodepatterns were fabricated using excimer laser direct-writing technique. The influenceof the process parameters （the excimer laser fluence and the stage velocity） on themicromachining quality （the etching depth and ridge height of the edge） of ITO patterns were experimentally studied. The effect of laser fluence and the speed ofworking platform on the fabrication quality were discussed. The lower laser fluenceand suitable platform speed will be very helpful to improve the edge quality ofpatterning of ITO. However, the recast ridge at the edge also was shown. Use of39%solution of hydrochloric acid made it possible to further minimize the recast ridge atthe edges.CO₂laser direct-writing ablation micromachining technique is used to fabricatethe microchannel on the polymethyl methacrylate （PMMA） substrate. Thecorrelation between the process parameters（the beam translational velocity and theprocessing number of times） and the micromachining quality （the width and thedepth of the microchannel） is investigated. when a laser is used to make ablation ofthe microchannel on the PMMA substrate with surface adhering water. Themicrochannel with a hydraulic diameter of80μm is fabricated under twoexperimental conditions, and the comparison experiment has been performed on themicrochannel with the relative roughness. It is found that the Relative Roughness isminished effectively. This paper presents an effective method for polishing themicrochannel and improving its surface quality based on excimer laser irradiationtechnique and irradiation with the CO₂laser beam in an unfocused condition. It isfound that the Roughness of microchannel is minished effectively. The averagesurface roughness （Ra） is17nm.