The Design And Realization Of Nozzle Array Based On Electrohydrodynamic Printing

Electrohydrodynamic printing (EHD printing) is considered one of the potential processes for patterning printing electronic devices due to high printing resolution and wide viscosity range. To meet the requirements of high fabrication efficiency and overcome the inefficiencies in dot by dot, it is very important to develop a stable, accurate, efficient and addressable nozzle array. However, the domestic and international research has just begun. In this dissertation, two kinds of Si-based nozzle array are designed and fabricated based on EHD printing principle and micro/nano manufacturing technologies. The systematic and thorough research has been performed on the mechanism of the jetting process, how to achieve stable, accurate and efficient printing, the addressable method and the functional pattern printing. The main research work and contributions of the dissertation are introduced as follows:Firstly, the mechanism of the cone-jet behaviour in EHD printing is studied. A numerical simulation model of the cone-jet behaviour is established. The mechanism of jet printing under the coupling function of electric and hydraulic is explored and the affecting laws of the process and structures parameters to the printing results are revealed.Secondly, a new design of planar Si-nozzle with Si nozzle layer and PDMS reservoir layer is developed. For the Si nozzle layer, the rationality of the self-designed MEMS fabricating procedure is validated by experiments. To achieve the stable printing of the Si nozzle, the treatments of insulation is proposed. The process window of the extreme printing performance is established by revealing the affecting laws of the duty cycle, substrate speed and working voltage to the printing resolution.Thirdly, a modified design of protruding Si-nozzle is proposed with Si nozzle layer and PMMA reservoir layer is developed. For the Si nozzle layer, the rationality of the self-designed MEMS fabricating procedure and the effectiveness of structure design of the protruding Si nozzle to reduce the meniscus-anchoring diameter are validated by experiments. The process window of the extreme printing resolution is established by revealing the affecting law of the duty cycle to the printing resolution. Furthermore, the parallel printing of a Si nozzle array is implemented and this can provide references for developing a high-level integrated nozzle array.Fourthly, the solving method to implement the addressable and automatic jetting of nozzle array is studied. After numerical simulation, a multi-level voltage method is proposed to achieve the addressable multi-nozzle EHD printing with high consistency. The corresponding experiments show the effectiveness of the method. A new method to implement the automatic drop-on-demand printing is proposed based on the image parsing and PMAC controlling techniques. It is achieved automatically for the users to input a bitmap and gain the printing results on the substrate.Finally, the application of the Si nozzle to print the high resolution quantum dots pattern is explored. The suitable quantum dots system is selected firstly and the affecting laws of the duty cycle and frequency of working voltage to the printing diameter are studied. The controllable printing of high resolution quantum dots is achieved and this supplies a digital manufacturing method to print the quantum dots light emitting diodes.