Fundamental Research Of A Novel Hybrid Additive Manufacturing Technology For The Folded Waveguide Slow-wave Structures

At present,with the increasing information transmission capacity and transmission rate,the frequency spectrum of microwave band application is already very crowded,so it is necessary to open up millimeter wave and terahertz frequency domain to obtain a wider working frequency band.When the operating frequency increases greatly,the key feature size of vacuum electronic devices decreases rapidly,which puts a great test on the precision of the processing technology.At this time,the machining accuracy of millimeter-wave or submillimeter-wave devices has approached the limit of traditional machining processes,and alternative MEMS processes,such as LIGA and EDM,have some problems,such as high complexity,high assembly difficulty and long machining cycle.Aiming at the requirement of integrated manufacturing of key metal components of vacuum electronic devices in millimeter-wave and submillimeter-wave frequency bands,this paper combines additive manufacturing technology with micro-electroforming technology,and proposes a new hybrid additive manufacturing technology.The additive manufacturing process can realize the rapid and free forming of three-dimensional parts,and has great potential for the integrated manufacturing of high-frequency vacuum electronic devices and their precision components.In this paper,key technical problems such as additive manufacturing of precision three-dimensional mold,seed layer deposition on the surface of three-dimensional mold,oxygen-free copper precision electroforming,and photo-curing resin mold removal have been broken through,and the sample of folded waveguide slow-wave structure working in220 GHz frequency band has been successfully manufactured,which provides a new method and idea for manufacturing precision metal parts in high-frequency vacuum electronic devices.1.The inverse model of the slow-wave structure of the folded waveguide of the traveling wave tube in the 220 GHz frequency band is designed,and the model was fabricated by the Stereo Lithography Appearance(SLA).2.The principle and parameters of the seed layer deposition process are explored.The most suitable process and parameters are determined to deposit a high-quality electroforming seed layer on the surface of the three-dimensional mold.3.The mechanism and effect of electroforming process are systematically studied in order to find out the best formula and parameters.A dense,high-purity metal is deposited that completely covers the mold.4.The mold after electroforming is modified by machining.The best method is adopted to remove the resin mold.Finally,a folded waveguide slow-wave metal structure is manufactured.5.The key dimensions such as narrow side length,single cycle length and depth of the slow-wave structures fabricated by the new hybrid additive manufacturing technology proposed in this paper are precisely measured.At the same time,the oxygen content in the slow-wave metal copper structure and the surface roughness are tested and characterized.The results show that the copper slow-wave structure in the220 GHz frequency band produced by this technology has the advantages of high precision,low oxygen content,smooth surface,etc.,and has strong stability and practicability.