Research On Micro-fluid Transfer Process Modeling And Control In The Chip-packaging Area

Micro-liquid dispensing technology, which requires microscale transfer and highconsistency of dispensing droplets, plays a crucial role in chip-packing industry and itdetermines the chip-packing quality. However, micro-liquid dispensing is a nonlinearsystem with multi-parameters, making it difficult to realize the high quality of dropletstransfer. Based on the factors affecting micro-liquid dispensing, this research explores theprocess of micro-liquid dispensing from the method of modeling, numerical stimulationand control, aiming at improving the consistency of dispensing droplets. The majorachievements are shown as follows:1) Research on the process of micro-liquid dispensing. Based on the major problemsin droplets transfer, this research analyzes the causes of these problems and the factorsaffecting droplets dispensing, then summarize the controllability and observability of thefactors, which lay a foundation for modeling and controlling the process of micro-liquiddispensing.2) Modeling for transient pressure response in air inflation and deflation of syringe.As the driving force for liquid’s extruding out of needle, transient pressure in air inflationand deflation of syringe cann’t be measured directly, therefore, the measured pressure inthe entrance of syringe is used. However, these two kinds of pressure are different. Thispaper establishes the model for pressure response in air inflation and deflation of syringeand tests the accuracy of model by comparing model pressure and simulation pressure. It isfound that the average error of transient pressure response in air inflation and deflation ofmodel is9.6%, which is far less than the average error24.1%of the pressure in entrance ofsyringe.3) Analyzing the dynamic stretching process when liquid contacts the substrate withthe influence of multi-parameters. After the liquid is extruded from the needle, it willcontacts substrate and then stretchs with the needle rising. When the liquid bridge isbreaking, some liquid will remains at the needle, which leads to that the actuallytransferring amount is not equal to the amount extruded. This paper firstly analyzes theinfluence of needle structure on the amount of extruded liquid and then establishes thedynamics model of liquid transferring process with multi-parameters. On this foundation,the dynamic process of liquid breaking is simulated numerically by combining thegas-liquid flow volume function model, Brackbill surface tension model and moving grid method to explore the influence of multi-parameters on micro-liquid transfer, includingcontact distance between substrate and needle, the speed of needle response and the contactangle.4) Developing a self-adaptive time/pressure switch control strategy based on dropletsvolume prediction model, which is established by modeling pneumatic parts and liquidextruded parts in micro-liquid dispensing. On the foundation of droplets volume predictionmodel, the self-adaptive time/pressure switch control strategy is adopted to control theliquid dispensing process by regarding time and pressure. It is founded that the predictionaccuracy of model towards the extruded amount of liquid is1%, the error of liqiud transferamount reduces from50%to7%and the consistency of micro-liquid dispensing is highlyimproved.