Reserch On Metal Micro Droplets On Demand Spraying And Deposition Process

In recent years,people's requirements for electronic products have gradually increased,and the demand has gradually increased.Therefore,the rate at which electronic products are upgraded is very high.In order to reduce the size and cost of electronic products,it is very important to study the fabrication methods of BGA solder balls and surface mounts for microelectronic packaging.Droplet injection molding technology was proposed and developed rapidly in the 1990 s.The injection process can be precisely controlled,providing a new direction for the development of BGA solder balls and the development of surface mount.In order to realize the production of uniform BGA solder balls and the printing and molding of solder paste,this project developed a set of on-demand metal droplet spraying and deposition system based on the pneumatic principle.Uniform lead-free solder particles were obtained using this system.The influencing factors for the formation of particles were discussed and preliminary experiments were carried out on their injection molding.This article mainly carried out the following research work:In this paper,firstly,the on-demand injection process of metal micro-droplets is simulated and analyzed.Under the action of gas pulse,the change of gas pressure in the crucible and the ejection process of the liquid drop are studied.The single-factor variable method was used to simulate the pressure fluctuations in the crucible under different parameters,and the influence of different parameters on the pressure fluctuation was analyzed.By changing the simulation parameters,different droplet ejection states were obtained,and the different ejection states and pressure fields of the droplets were analyzed.At the same time,the influence of ejection parameters on the fluid flow elongation and ejection velocity was studied.Through the on-demand injection of metal micro-droplets and the decomposition of the deposition system's functions,the specific implementation of each function was determined.The gas path of the system is designed to achieve a reduction in the oxygen concentration of the system and a gas supply to the injection device is achieved.The signal generated by the data acquisition card is used to control the on-off of the solenoid valve,and a gas pulse is generated under the action of the pressure to drive the generation of the droplet.The motion control card is used to control the stepping motor platform to build the motion system,and the motion control circuit is designed at the same time.Lab VIEW software was used to compile the system driver program and achieve the jet printing function.The above-designed system was integrated and the integrated system was used for the injection experiment.The injection condition was determined under certain conditions and the feasibility of the system was verified.The single-factor experiment method was used to analyze the droplet diameter and uniformity of the experimental parameters.The trend of sexual influence.The deposition experiments were performed using the system,and the accuracy of the printed line arrays and surface arrays was analyzed;twodimensional graphic printing was repeated and simple three-dimensional articles were obtained.The experiment proves that the system can produce uniform solder balls of different sizes.At the same time,it verifies that the system has the ability of jet printing and can realize the stacking of droplets.