| In recent years,optical thin-film have developed rapidly in new energy and energy-saving technologies,new media,and information technology.The micro structure of the optical film surface can effectively improve the light efficiency and light utilization.The mass production of optical films depends on the hot embossing and UV curing technology,both of which need to print the microstructure from the working mold onto the polymer film.Precision electroforming technology has become the main method of manufacturing working mold due to its advantages of high surface reproduction precision and high production efficiency.The electroforming quality of the working mold is determined by the quality of electrodeposition and demoulding.However,there are several studies on how electrodeposition efficiency can be enhanced but there are still great challenges on how the accuracy of a single microstructure and the integrity of surface microstructure of large area forming mold can be taken into account.In order to solve the problem of the decrease of mold accuracy caused by excessive bonding force in the demoulding process,the role of coating in demoulding is studied in this thesis,the role of coating in demoulding was studied.Using polymer optical film as the original mold,Cr coating was fabricated by magnetron sputtering to assist demoulding.The fabrication process of Cr coating and the mechanism of reducing adhesion were analyzed systematically,and the coating process parameters were optimized.The main research contents are as follows:(1)The manufacturing process of Cr coating.The Cr coating was prepared by magnetron sputtering,and the basic principle of magnetron sputtering and the measurement and correction of film deposition thickness are studied theoretically.The coating was characterized by contact angle,surface energy,XRD and XPS.The effects of sputtering power,sputtering time,substrate temperature,argon flow rate and rotational speed of sample table on the thickness of Cr coating and the surface roughness of PET master mold were studied.The results show that the sputtering power,time and argon flow rate have obvious influence on the thickness of Cr coating,and the deposition thickness and uniformity of the coating have the greatest influence on the surface roughness.(2)Micro electroforming process of PET optical film mold.The experimental platform of micro electroforming was built,and two groups of comparison schemes were studied.The electroforming demoulding strength,casting surface roughness,micro-morphology and reverse reflection coefficient were measured and analyzed by laser confocal microscope,scanning electron microscope,reverse reflection mark measuring instrument and dynamometer.The results show that the Cr coating can effectively reduce the release force of electroforming and improve the surface quality and optical properties of the duplicated mold.(3)Optimization of process parameters for Cr coating.The effects of sputtering power,sputtering time,substrate temperature,argon flow rate and rotating speed of sample stage on the demoulding strength,surface roughness and retroreflection coefficient of castings were studied by orthogonal test.Through matrix analysis,the optimal scheme of orthogonal experiment is obtained as follows: sputtering power is 250 W,sputtering time is 15 s,substrate temperature is20 ?,argon flow rate is 30 sccm,sample table speed is 20 rpm.The primary and secondary order of the influence of various factors on the index value of orthogonal experiment is as follows:sputtering time > rotational speed of sample table > argon flow rate > sputtering power >substrate temperature.(4)The mechanism of Cr coating reducing interfacial adhesion was analyzed.Four groups of Cr coatings with different thickness were set up in the experiment,and the mold surface of PET film was observed by optical contact angle meter,X-ray photoelectron spectrometer and optical confocal microscope.The results show that with the increase of Cr coating thickness,the polar oxygen containing functional groups(C-O bonds and C=O bonds)on the film surface decrease obviously,the surface is hydrophobic,the surface energy can be reduced,and the surface adhesion decreases,and the presence of Cr improves the crystallinity of Ag conductive layer.Through the mechanism study,the effects of various factors on the demoulding strength and roughness were analyzed. |
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