Structural Design And Performance Test Of Vibrating Plate Of Piezoelectric Inkjet Print Head

As an important branch of inkjet printing technology,piezoelectric inkjet printing technology is increasingly used in the fields of printed electronics,cell printing and biopharmaceuticals due to its advantages of high print resolution,low cost,long service life and good ink compatibility.However,the domestic research on piezoelectric inkjet print heads started late,and the patented technology of its core component piezoelectric vibrating plate is mastered by foreign companies.This article aims to independently design a low-cost,mass-produced piezoelectric inkjet printhead vibrating plate structure to break the technical barriers.In this paper,suitable vibration plate materials and process methods are selected to design and simulate the structural dimensions.The piezoelectric inkjet printhead vibration plate is successfully prepared,and its vibration performance is tested by a Doppler vibrometer.Finally,the inkjet ejection test is conducted on the piezoelectric inkjet printhead.The main research contents are as follows:?1?Combined with patents and literature,the mechanical properties and preparation process complexity of commonly used vibration plate materials were analyzed,a two-inch single-crystal silicon wafer with a thickness of 300?m was selected,and SiO₂ was used as an elastic plate layer;combining piezoelectricity,dielectricity and fatigue,Lead zirconate titanate?PZT?was selected as the piezoelectric material;comparing the influence of metallic and non-metallic materials on the piezoelectric performance of PZT,Pt/Ti was selected as the PZT bottom electrode and Cu/Au/Cr as the PZT top electrode;Select polyimide?PI?as the protective layer;finally select the optimized MEMS process to prepare the vibration plate structure.?2?Set up a vibration plate simulation model in COMSOL,study the impact of each structural size on the vibration plate amplitude,and combine the possible problems in the process to finally determine the appropriate size combination.The width,length and thickness of the SiO₂ elastic layer were 2400?m,300?m and 0.2?m;the thickness of the Cu top electrode were 0.7?m,0.8?m,0.9?m,and the thickness of the PZT piezoelectric layer were 1.2?m,1.4?m,1.60?m;the width of the PZT film was 160?m and 180?m.?3?According to the structural characteristics and experimental conditions of the vibration plate,the MEMS preparation process of the piezoelectric vibration plate was determined,the dry oxygen oxidation method was selected to prepare SiO₂,the oxidation time was controlled to30min to obtain SiO₂ with a thickness of 200nm;Pt/Ti was prepared by magnetron sputtering method and patterned by aqua regia corrosion;PZT was prepared by sol-gel method and spring structure was obtained by etching process;The magnetron sputtering method was used to prepare Cu/Au/Cr,and the corresponding etching solution was configured to pattern it;The deep reactive ion etching process was selected to release the vibration plate,and through multiple rounds of etching,a silicon cup structure with vertical sidewalls was obtained.?4?The multi-step etching process was used to reduce the side erosion problem during the patterning of the electrode on Cu.By studying the reaction mechanism of the intermediate product CuCl generated during the etching process,KCl solution was selected as the intermediate etching solution.The concentration of the first etching solution FeCl₃ was optimized,and the influence of corrosion rate on the amount of side corrosion was studied and finally the amount of side corrosion was reduced from 25?m to 5?m.?5?The Doppler vibration test of the vibration plate was carried out to study the effect of its actual vibration mode and main structural parameters on the amplitude,and compared with the simulation results to verify the rationality of the vibration plate structural design.Finally,the self-built inkjet test platform was used to test the complete piezoelectric inkjet print head,and the ink droplet ejection was successfully achieved to verify the feasibility of the program.