Research On PCBA Carbon Dioxide Snow Robot Cleaning System

With the rapid development of science and technology,people's demand and dependence on electronic products are greatly improved.As the core component of electronic products,the reliability of Printed Circuit Board Assembly(PCBA)directly affects the life of electronic products.Therefore,people have been searching for an efficient cleaning method for PCBA.Carbon dioxide snow cleaning has a good performance in cleaning metal surface,semiconductor components,precision instruments and so on.It not only has no damage to the surface of electronic components,but also as a green cleaning technology,it has less impact on the environment and no residual by-products.However,the systematic use of carbon dioxide snow cleaning technology to clean PCBA still needs to be realized.The reasonable structure design and cleaning scheme still need to be studied.This thesis analyzes the literature and related data of carbon dioxide snow cleaning.On this basis,the cleaning mechanism of carbon dioxide snow is studied.Based on an industrial six axis robot,a set of PCBA carbon dioxide snow robot cleaning system is designed.The numerical simulation of the designed nozzle is carried out.Through experiments,the factors influencing the cleaning effect and cleaning efficiency of the system are explored,and the cleaning scheme is optimized.Research works in this thesis are summarized as follows:(1)The research and development status of carbon dioxide snow cleaning technology and PCBA cleaning method are summarized,and the significance of carbon dioxide snow cleaning technology for PCBA is clarified.(2)The cleaning mechanism of carbon dioxide snow in solid particle cleaning and organic matter cleaning is explored.The influencing factors of carbon dioxide snowflake formation are analyzed theoretically.Combined with the results of theoretical analysis,the methods to improve the effect of snowflake formation are put forward.(3)A set of PCBA carbon dioxide snow robot cleaning system is designed,including the selection of carbon dioxide source and compressed air source,the design of pneumatic circuit,the design of control circuit,the design of injector and nozzle,the design of PCBA fixture,the trajectory optimization of industrial six axis robot and the construction of the overall experimental platform.(4)The flow fields of the straight through nozzle,duckbill nozzle and Venturi nozzle are simulated by ANSYS fluent combined with the theory of computational fluid dynamics.The flow state of compressed air,the position distribution,velocity distribution and particle size distribution of carbon dioxide snowflake particles are analyzed based on the simulation results.(5)Based on the designed PCBA carbon dioxide snow robot cleaning system,the cleaning experimental platform is built.The factors influencing the snow forming and cleaning characteristics of PCBA carbon dioxide snow robot cleaning system are studied,and the cleaning efficiency of the system is explored.Combined with the problems found in the experiment,the cleaning scheme is optimized to a certain extent,and the good cleaning effect is improved,and the matters needing attention in the actual operation of PCBA carbon dioxide snow robot cleaning system are given.