Experimental Research On Electroforming Technology Of Conical Inner Surface Corrugated Microstructure

Complex micro-structures are increasingly applied in widespread applications such as aviation,microelectronics,information and communication.As a precision nontraditional machining technique,electroforming uses electrochemical cathodic deposition to produce metal parts.In view of no tool wear and the high precision,electroforming has been widely employed in manufacturing complex micro structural parts,especially for the complex cavity structure,small size and high precision machining of metal parts that traditional processing techniques are difficult to achieve.In this paper,the processing of the conical corrugated microstructure on the inner surface has been studied,and a combinatorial electroforming method was proposed to processed conical corrugated horn microstructure with complex cavity structure.The main research works are as follows:(1)The process route was determined.Firstly,the micro-copper ring and the micro-nickel ring were prepared by the electroforming technology based on the UV-LIGA process and assembled to obtain the combined mandrel.Secondly,after the combined mandrel was electroformed,selective dissolution was carried out to obtain a conical corrugated microstructure on the inner surface.(2)The electroforming-mould was fabricated by using thick film sheets of SU-8 photoresist of150μm in thickness based on UV-LIGA technology.The influence of the process parameters such as lamination,prebaking,exposing,post-baking and development on the quality of SU-8 photoresist mould were studied.And SU-8 moulds with good topography and excellent adhesion to metal substrate were produced successfully by using the optimal parameters,which thickness 150μm,line width 300μm(3)Micro electroforming process of the micro-copper ring and micro-nickel ring was researched.And the effects of different machining parameters for the surface quality and performance of electroformed deposit were investigated,namely electroforming solution ratio,current density.By using the low copper sulfate electroforming solution and current density of 0.5A/dm~2,micro-copper rings of different sizes with smooth and dense surface were obtained.And the nickel-sulfamate solution system and current density of 0.5A/dm~2 was used to prepare micro-nickel rings of different sizes with smooth and dense surface.And micro copper rings and micro nickel rings with thickness of150μm and ring width 300μm were fabricated with optimized parameters.(4)The selective dissolution test of micro-copper ring and micro-nickel ring in the combined mandrel was studied.The results show that the TFG nickel etchant can selectively dissolve Cu and Ni,and the dissolution rates of copper and nickel under different process conditions were studied,and it was found that the TFG nickel etchant heated at 65℃in water bath completely dissolves the nickel material under mechanical agitation,whereas the copper material dissolves only 8.97%.And the electroforming of conical corrugated horn was carried out by using a well-assembled composite mandrel,and the nickel was selectively dissolved.