Fabrication Of Nickel Template For Micro And Nano-injection Molding

Compared with other micro/nano structured materials,polymer products with micro/nano structures have superior mechanical and optical properties and strong chemical corrosion resistance.Therefore,in recent years,the demand for polymers with micro/nano structures on the surface has gradually increased,such as antireflection coatings,surfaces of anti-adhesion of stains,or cell culture and differentiation.Injection molding is considered as the most effective technology for mass-producing polymer products,but the resolution of the molded structure is limited.Nanoimprint lithography(NIL)can achieve high resolution micro and nanostructures duplication to the polymer surfaces,but the yield is extremely low,which is not suitable for industrial production.Templates fabricated through conventional CMOS compatible processes generally adopt relatively brittle materials,such as silicon and quartz,which cannot withstand high temperature and pressure,therefore,it cannot be directly used in injection molding.Therefore,fabrication of high-strength templates with micro/nano structures is of great significance for injection molding mass production of polymer products with micro/nano structures.In order to solve the aforementioned problems,this thesis combines the nanoimprint with electroplating process,to obtain high-strength nickel template with micro/nano structures which can be used for injection molding,so that the polymer products with micro/nano structures can be mass produced in low cost.The main work of this thesis are as follows:In the second chapter,the silicon master template was fabricated using CMOS process.The target patterns were first drawn into the resist by laser direct writing and development,then the patterns were transferred into silicon substrate via inductively coupled plasma etching,and then the remaining resist was removed.Then the silicon master template was duplicated into polycarbonate template through UV nanoimprint lithography.The polycarbonate template was used as master mold for subsequent electroplating.In the third chapter,the deposition of nickel seed layer growth by magnetron sputtering was studied.The influences of different substrate materials,different sputtering conditions,and seed layer thickness on the surface morphology,surface roughness and internal stress of the seed layer were studied.The optimal sputtering conditions at room temperature and preferable thickness of the seed layer were obtained,results showed that 75 nm seed layer was the best thickness.In the fourth chapter,the influence of the electroplating current density on the architecture and mechanical properties of the nickel template was studied and optimized.The current density of electroplating has huge influence on the electroplated nickel template properties.The corresponding nickel templates with micro-nano structure were electroplated at different current densities,and then the surface morphology,microstructure and mechanical properties of these nickel templates were studied and analyzed using SEM,XRD and nanoindentation,respectively.The optimal electroplating current density is obtained.The optimal current density 0.6 A/dm2 results in the smallest nickel gran size of 21.5 nm,which provides the largest Young's modulus and hardness values of 191.39 GPa and 7.46 GPa,respectively.In the fifth chapter,using Autodesk Moldflow(Autodesk Inc.)software to simulate and analyze the flow process of micro/nano structure injection molding,and to explore the influence of different injection parameters on product quality,and then obtaining the optimal injection molding process conditions.The initial mold temperature and melt temperature were set at 50 ? and 225 ?,and the packing pressure was 80 MPa.This thesis studied thoroughly the influences of different fabrication conditions on nickel template used for micro/nano injection molding,and obtained the optimal parameters of key processes,and theoretically analyzed the flow process of injection molding using Autodesk Moldflow simulation.The whole fabrication process has high reference value for application in industrial production.