The Study On Automatic High-power LED Intelligent Micro-coating System

LED has become a hot spot of competition in the international emerging strategic industry.High power LED packaging,as an important link in the industrial chain,is the core manufacturing technology to promote the industrialization and practicality of semiconductor lighting.At present,most LED manufacturers adopt the traditional LED dispensing process and printing process.These two ways all have uneven coating thickness,poor chromatic aberration and low luminous efficiency,which lead to poor packaging quality and low automation of coating.Phosphor,which mixed by phosphor powder with fluorescent powder glue in a reasonable proportion,is a non-Newtonian fluid.It is more complicated than Newtonian fluid.The result of coating phosphor layer are affected by multiple control parameters.In order to solve these problems,this paper focuses on the automatic micro power coating process of high power LED,and realizes the full-automatic LED intelligent micro coating system.The main contents are as follows:(1)According to the micro coating process and the process control parameters required,and users' demand,this paper analyzes functional requirements of micro-coating system of phosphor,designs the overall framework of the system and divides the whole system into two parts: upper machine and lower machine system.This paper all defines every functional definition and the types of input and output port,avoiding functional redundancy.(2)According to the design target,this paper construct the hardware platform of the lower machine control system,including two parts,one is the selection of key hardware devices,and the other is the establishment of the control system of the lower computer.In this paper,we choose different types of sprinklers on the market to test the models,mainly considering the spray radius,nozzle shape,whether it can withstand high viscosity liquids without plugging powder,and the size and shape of coated chips or modules.By comparing the results of the experiment,the EFD-781 nozzle is selected as the spray head of the 108mm*108mm CSP LED.(3)In the process of phosphor micro-coating,the coating effect will be influenced by several control parameters.As a typical non-Newtonian fluid,the shear force and the strain force of the phosphor are nonlinear.Through several experiments to explore the relationship between the effect of phosphor coating and the control parameters,a PID control algorithm based on BP neural network is proposed to control the volume of phosphor flow in the transmission pipeline at a unit time,so as to ensure the single-layer coating thickness constant.On this basis,through the on-line parameter tuning algorithm of the upper computer,this system can calculate the optimal control parameter combination meeting the desired effect of the user.(4)According to the micro coating process and the required control parameters,this paper set up the upper computer of intelligent micro coating system,including human-machine interaction module,database module,serial communication module and parameter setting module.User can control the working state of the system in real time through the client's human-computer interaction interface,so as to achieve the purpose of intelligent coating.