Research On High-Speed Jetting Dispenser With Compact And Dual Piezostack-Driven Design

Fluid dispensing is an important means of microelectronic packaging technology,which is used to dispense precisely by means of a controlled way.In recent years,the piezo-driven dispensing technology of the fluid dispensing technology gradually became a mainstream technique.Compared to the previous jetting dispensing technology,the piezo-driven dispensing technology has advantages of a wide range of viscosity,high jetting efficiency,good consistency,and has become an important direction in the development of fluid dispensing technology.Based on our many years'experience,this paper designed a compact jetting dispenser with independent intellectual property rights using dual-piezoelectric stacks as the driving source,aiming to low efficiency,high dot volume and low jetting precision in domestic field of jetting dispensing technology and hoping to achieve high-frequency and micro-jetting of colloid.The main research work in this paper is as follows:(1)The displacement amplifier structure for driving was presented,the stress and performance of the amplifier were decided by theoretical analysis and finite element analysis.A prototype of the designed amplifier was manufactured based on the theoretical guidance.The testing results showed the displacement output of the amplifier is 320?m while the driving piezoelectric stack was connected to square-wave 144V,which fits with the simulation results,fulfilling the requirements of piezo-driven jetting dispenser.(2)The matching method of needle-nozzle was proposed.Theoretical analysis has been carried out to understand dispensing process of piezo-driven dispenser with the help of a fluid dynamic model.Then the jetting performance comparison between no-cap stem and stem with a cap in the nozzle chamber by fluid dynamic analysis was obtained,and the influence of dimensional parameters of nozzle and stem,glue viscosity,pressure and stem displacement were simulated and analyzed.Finally,the jetting regularity of the nozzle design is obtained.(3)The overall design and assembling of the dispenser were completed with the introducing of a displacement sensor.A complete testing system with subsystems includes the driving and control system,the motion platform with pneumatic control system.(4)Glycerol/ethanol mixture was used as dispensing materials after comparative analysis.Testing experiments and corresponding analysis of feed pressure,duty cycle and frequency were accomplished.In the tests,the highest jetting frequency reached 350Hz and minimum droplet diameter is 0.42mm using the glycerol/ethanol mixture with a viscosity of 500cps under a duty cycle of 2%.