Dynamic Modeling And Scale Control Of Dam Print-fill Process In Electronic Packaging Area

The dam print-fill process,as a fixed packaging technology for electronic packaging,acts as a plastic housing for integrated circuit chips,and plays a role in placing,fixing,sealing,protecting the chip,and enhancing electrical heating performance.The technical principle is that the encapsulation fluid in the nozzle is continuously extruded from the nozzle by a given pressure,and then the nozzle is moved according to a predetermined route to spread and deposit the fluid on the substrate,and finally solidify and form.After the fluid is applied to the substrate,it is affected by inertial force,surface tension,and viscous force,which changes its forming morphology,and then affects the final deposition morphology and scale of the fluid.This paper combines theoretical models,numerical methods,numerical simulations,and experiments to establish a fluid extrusion molding model and a dam print-fill dynamic model,then related researches on the regulation of print-fill forming dimensions are made from the aspects of process modeling,numerical simulation and experiments.The main work and research results of the paper are as follows:1)The theoretical model of macroscopic fluid flow,the model of gas filling and deflation inside the nozzle,and the model of flow parameters are analyzed and established,and then the scale model of fluid deposition is established.Then take the width as an example to verify the accuracy of the scale model through numerical simulation.The results show that both the gas source pressure and the substrate speed will affect the fluid forming width,and the prediction errors of the model are all below 9%.The results can provide the necessary foundation for the subsequent research on the dam forming process.2)The dynamic scale model of the dam print-fill process is established.Then,a theoretical analysis of the relationship between the corner radius and the height and width parameters of the dam during the printing process shows that there is a monotonic relationship between them.In theory,the size of the corner radius can be controlled by adjusting the width or height of the dam,and the opposite is also true.Then,a self-built pneumatically driven fluid extrusion system is used to conduct a trial printing experiment.The results show that the fluid deposition height,width,and mass flow rate has a linear relationship with the gas source pressure,and all the standard deviation show no significant fluctuations.This shows that the experimental system constructed in this paper can show uniform,precise and controllable fluid filamentary deposition.Finally,the accuracy of the dynamic model is verified by simulation and experiments on the print-fill process of the dam.The results show that the prediction model errors are all below 5%,which can provide guidance for subsequent scale control.3)Methods to determine whether the influencing factors and scale control parameters of the dam print-fill process can be measured and adjusted are analyzed and established.Then,through numerical simulations and experiments,the effect of printing forming factors on the control mechanism of its forming scale is researched.The results show that both the printing height and the outer area increase with the increase of the pressure of the air source,but the inner area decreases with it,and with the increase of the substrate speed,the result is exactly the opposite.Then,when the pressure and speed conditions of the simulation and experiment are 350 kpa and 7.5mm/s,350 kpa and 15mm/s respectively,the corresponding dimensions are the best parameters.Finally,the orthogonal experiment method is used to research the regulating mechanism of the influencing factors of filling forming on its forming scale by numerical simulation.The results show that as the pressure of the gas source increases,the average value of the filling height,volume,and volume ratio will increase,but as the filling speed and trajectory distance increase,the results will decrease.For the filling area with a side length of 20 mm,a dam height of 1.7mm and a width of 3.4mm,the optimal conditions for obtaining the ideal filling size are: the air source pressure is 170 kpa,the filling speed is 18mm/s,and the track spacing is 2.2mm.