| In many industries, especially in the microelectronics industry, dispensing technologyplays an important role as a controllable precision manner for fluid delivery. With thethriving of electronics market, traditional contact dispensing technology is difficult to meetthe needs of the market. The jet dispensing technology with a high frequency and accuracyis occupying the markets of electronic packaging. A new type piezoelectric-hydraulicamplification driving jet dispensing device is proposed in this paper, which actuated bypiezoelectric stack and the hydraulic amplification mechanism is designed to meet therequirements of the striker displacement. Accordingly, the mechanism of the jet dispensingdevice is researched.First, the research status and significance of the non-contact jetting dispensingtechnology is analyzed in the paper. The material properties and the structure of thepiezoelectric stack are introduced. The output characteristics of the piezoelectric stack areanalyzed. Based on the analysis, the relation between output force and output displacementof the piezoelectric stack is determined.Second, the working principle of the non-contact jetting dispensing is analyzed indetail. Based on the properties of the adhesive, the mechanics model of the droplet at thenozzle outlet is established and the conditions of droplet ejection are deduced further. Thefluid flow mechanism of the dispensing process in the injection chamber is studied vianonlinear finite element software FLUENT. The influences of the internal structureparameter of hitting type between the striker and nozzle, the gap between the striker and theside wall and the nozzle diameter on jet dispensing and the external control factors ofimpact velocity, supply adhesive pressure and viscosity of the glue are analyzed.Furthermore, the work principle of the piezoelectric-hydraulic amplification driving jetdispensing is analyzed, and detailed theoretical analysis of the hydraulic amplificationsystem in the dispensing device is conducted to determine the size of the basic structure.According to the dispense jet principle, the vibration model of the jetting device isestablished and the movement of the firing pin actuated by the square wave signal is studiedvia the software SIMULINK. Based on this, the relation between the striker displacement and speed is obtained. The prototype is developed and the dispensing system is set up. Thefunctions and the implementation of the subsystems are analyzed.Finally, according to the test requirements the test platform is build. The test results ofthe piezoelectric-hydraulic amplification performance show that the amplificationperformance can meet the requirements of dispensing. The influences of square ware signalsof amplitude and frequency, supply adhesive pressure and viscosity of the glue on theadhesive jetting volume are analyzed to ensure the dispensing properties. According to theexperimental result, with110V voltage drive, the hydraulic amplification system has astable amplification of5.42times, and the output displacement is0.515mm; the jetdispensing device can apply to the liquid viscosity at0~3500cps. The minimum jettingvolume is about0.437μL, the dispensing frequency is0~143Hz, and the dispensingconsistency is controlled in6.62%. |
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