Research On Jetting Behavior And Key Technologies Of Liquid Metal Electromagnetic Micro Jetting

Compared with the traditional contact dispensing technology,non-contact liquid droplet jetting technology has the advantages of high speed,good quality,low cost and wide application range and so on.Non contact jetting technology was widely used in microelectronic packaging industy,it make the dispensing technology develop from contact to non-contact micro jetting.Liquid metal micro droplet jetting technology can meet the new requirements of electronic packaging technology,and it has a great application prospect in the fields of metal 3D printing,physiological electrode,liquid metal biomaterials and so on.Improving the stability of jetting and uniformity of droplets are the important issues which dominate the application and development of liquid metal micro jetting technology.In this dissertation,a liquid metal electromagnetic micro jetting technology scheme is proposed,and the regulation of liquid metal electromagnetic micro jetting,jetting behavior and control are studied,and explore the application of liquid metal electromagnetic micro jetting technology in electronic packaging,3D printing and other fields.In order to verify the feasibility of liquid metal electromagnetic micro jetting technology,using mercury as a jetting material,designed the electromagnetic micro jetting valve,set up micro jet experiment platform,carried out the dot matrix printing,pattern printing,jetting behavior,jetting frequency test,current pulse width test and so on.Experimental result show that the liquid metal micro jetting platform is stable,the highest jetting frequency can reach 204.5Hz,the average droplet diameter deviation of 2.27%,have good uniform,the minimum metal droplet diameter is 52?m.It verify the feasibility of liquid metal electromagnetic micro jetting technology,but also show the superiority of the electromagnetic micro jetting technology in the jetting frequency and stability etc..In order to further understand the metal fluid behavior in the electromagnetic micro jetting process,the multi-field coupling electromagnetic micro jetting metal fluid behavior was studied by orthogonal numerical simulation.This is conducive to the optimization of the micro jetting valve structure,and the better regulation of the micro jetting behavior.The boundary conditions of the electric field,magnetic field and flow field in the electromagnetic micro jetting valve are determined by experiments and theoretical analysis.The distribution of magnetic field and current density is obtained by single field simulation.Then the current density is taken as the load of the magnetic field,and the Lorenz force field is obtained by the multi-field simulation.At last the Lorenz force field acting on the fluid inside,the fluid flow process is simulated.Three kinds of micro jetting valve with different passage are analsised through multi-field coupling,the bottom cone flow passage with best performance is obtained.Based on the bottom cone jetting valve,the key dimensions are orthogonal combinated.Nine orthogonal models are simulated,the results show that the main factors affecting electromagnetic micro jetting valve outlet pressure are the electrode distance,fllowed by the width of liquid metal groove,and the groove height belongs to relatively minor factors.In considering the working hours,get the best dimensions combination electrode distance 36mm,width 4mm,height 46mm.At the same time,3 kinds of nozzle structure are fluid simulated,and the conical nozzle structure with small pressure loss is obtained.The whole numerical simulation analysis provides a theoretical basis for the design of liquid metal electromagnetic micro jetting valve.The solder electromagnetic system is designed and developed,integrated electromagnetic micro jetting valve,three-dimensional mobile platform,image recognition and positioning,high current pulse control,temperature control,pressure control module.The solder electromagnetic micro jetting system is in normal operation,as an experimental prototype.Based on this,the experimental study of the electromagnetic droplet jetting of the solder was carried out.Through the analysis of the formation mechanism of the droplet and the process of the liquid jet,the droplet jetting behavior was studied.The influences regulation parameters on the electromagnetic behavior of micro jetting are investigated,including the working temperature,electrode voltage,current,pulse width,nozzle diameter,collecting plate distance and so on.The effects of various parameters on droplet diameter,droplet shape and consistency were obtained,and the durability of electromagnetic micro jetting system is tested.Finally,the preliminary application of liquid metal electromagnetic micro jetting technology is explored,including LED lamp welding,resistance welding,surface mount welding,mobile phone camera module VCM voice coil motor device welding,connecting finger welding,metal 3D-printed etc.The results of this thesis would help to better understanding the regularity of liquid metal electromagnetic jetting,realize the effective control of droplet jetting behavior of liquid metal,and improve the liquid metal droplet jetting stability and uniformity,and would promote the development of liquid metal electromagnetic micro jetting equipment and its industrialization.