Structural Design Manufacturing And Process Optimization Of Micro Actuator Membranes For Inkjet Piezoelectric Printhead

Inkjet printing technology has been rapidly expanding from the initial limitation to many different fields such as cells printing,microelectronics,biological pharmacy.It has been great change in technical level,the print head of DPI?dots per inch?,ink quantity volume,injection speed,inkjet power and other key indicators have got great improvement and optimization.The current inkjet printing equipment has advantages like good stability,injection speed,low power consumption,high resolution,easy to control drops.The emergence of piezoelectric inkjet printing technology has transformed industry,as a part of ink print head,the research of actuator membrane can not allow to ignore.Actuator membrane can provide enough power for drops injection.Reasonable structure and size design for the actuator membrane to realize high integration.The appropriate technique selection will affect the service life and vibration performance of the print head.Therefore,in this paper,combining with domestic and foreign research literature and based on this basis,conduct a study to the actuator membrane structure of the piezoelectric inkjet print head,the main research content as follows:?1?Based on the simulation and technological conditions of Comsol finite element software,the structural materials were selected and optimized.The material properties of various preparation processes were compared and the actual conditions of the laboratory were analyzed to select the most suitable process for this structure.The<100>crystal to four inches of silicon as the substrate,the structure of actuator membrane determines the platinum?Pt?as the top and bottom electrode,silica?SiO₂?as the elastic layer,lead zirconate titanate?PZT?thin film as piezoelectric element.And release the final actuator membrane by the combined dry and wet method.?2?After determined the good materials and technology,combining with the characteristics of MEMS processing,the integrative design and processing plan of actuator membrane was presented.Wet etching was used to release most of the silicon cup first,and then the front structure was prepared,finally the whole silicon cup was released by deep reactive ion etching?DRIE?.The process was optimized,such as PDMS was innovative used as the mask when the silicon cup etched in the KOH and worked well.And the water bath temperature of hydrofluoric acid buffer was adjusted to control the corrosion uniformity and lateral erosion of the oxide layer.?3?After the aqua regia corrosion of Pt,negative photoresist was spined as the mask,when the mask was removed and many scums remained.A novel double resist layer method was presented to decrease the negative photoresist scum.Positive photoresist that easy removed was chosen as the bottom layer resist and negative photoresist which has high ratio of anti-etch as the top layer resist.The bottom resist was choosen by its property,and the thickness and the retracting distance of bottom layer resist with respect to the top layer resist was optimized,to achieve the best effect of removing scum.?4?The actuator membrane of piezoelectric inkjet printing head conducted a Laser Doppler test,the vibration quality of the actuator membranes was tested.The rationality and practicability of the structure were verified.The chamber was fabricated by SU-8 photoresist to achieve the print head integrative manufacturing.Inkjet was tested and successful jeted ball drops with volume of 12pL,the feasibility of integrated piezoelectric inkjet print head was proved.