Piezoelectric Inkjet Structure Design And Its Manufacturing Process Optimization

Ink-jet printing technology is a kind of printing technology with non-contact and high-quality output image, and has an important position in many field of printing technology. Therefore, as one of the important type of the printing technology, ink-jet printing technology has been used widely in printing industry, cell printing, and electronics manufacturing due to its fast response, non-contact, high resolution, longer service life and low requirement of ink performance. Which illustrates the piezoelectric inkjet technology with enormous commercial values. However, the research on piezoelectric inkjet technology mainly focus on inkjet technology theory in our country. This technique is relatively backward in our nation and products mainly come from import. This project aims to break the foreign monopoly and the patent bastion, and to master the core technology of inkjet technology. In this paper, piezoelectric inkjet print head was fabricated through a series of design and manufacturing process, and the rationality of the structure were verified through the inkjet tests. The main research work of this dissertation is summarized as follows:(1) Based on the theory model of piezoelectric driven analysis, and combined with relevant patents and literature, a new type of piezoelectric print head structure was designed, and the structural size was optimized by using the software COMSOL. We choosed suitable materials for each part of piezoelectric inkjet print head structure by comparing materials property, and the structural materials were used as follows:used the silicon as the substrate material, and the thickness of substrate is 300?m, used the SiO2 with thickness of 500 nm as vibration plate, used the platinum with the thickness of 200 nm as the bottom electrode, used the PZT thin film with thickness of 1 ?m as actuator plate, used the platinum with the thickness of 150?m as top electrode, used the Parylene with the thickness of 350 nm as the protective layer, and used the SU-8 as the chamber material.(2) According to the relevant MEMS technology, we designed a manufacture technology project for piezoelectric inkjet print head, and the manufacturing process and equipment used for fabrication was analyzed and described in detail. The manufacturing processes parameters were optimized by comparing the advantages and disadvantages of each fabricate process and combined with the actual operation. The main process methods were shown as follows:lithography, oxidation, wet etching, plasma etching reaction, plasma sputtering, evaporation and etc.(3) Each nozzle fabrication project was analyzed, and plasma etching parameters of SU-8 were introduced and optimized in this paper. Finally, we chose 5 min as the etching time,20 mbar as chamber pressure,100 W as etching power, and the gas concentration is CF4·O2=120. Used this optimized parameters to etch SU-8. The higher etching rate and better etching profile for etching SU-8 were achieved by the optimized parameters.(4) Used doppler laser tester for piezoelectric thin film vibration performance test, and build test platform to observe and test the piezoelectric nozzle inkjet, proved the feasibility of manufacturing process and the rationality of the structure.