Deposition of Insulation Layers onto Fine Electrodes of PZT Multilayer Actuator via Electrophoretic Technique

• Main Authors: Hong, Yong-Tai, 洪永泰
• Other Authors: Rong-Fuh Louh
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/94119523873418288725

碩士 === 逢甲大學 === 材料科學研究所 === 85 === Multilayer piezoelectric actuators have been utilized as various electromechanical devices in the area of precision or automatic control industry, which have a substantial impact on technological advances. Multilayer piezoelectric actuators processing is similar to that of multilayer ceramic capacitors, except that additional steps are required to deposit the insulation layers on the end surface of inh electrodes to interconnect every other inner electrodes for miniaturization needs and device performance enhancement. The thrust for choosing electrophoretic deposition (EPD) method is due to several beneficial aspects such as process simplicity, low apparatus cost, rapid deposition rate, and ability for fine pattern coating of 2~4 mm linewidth.The results showed that micron-sized Zn-B-Si-O glass suspended in the 100 ml of ethylacetate and isopropryl alcohol solution with addition of 50 ml tetramethylammonia hydride (TMAH) and 2000 ml nitrocellulose (NC) had better EPD efficiency. The deposited glass insulation layers were fired at 660oC. The dense and pinhole-free insulation layers can be achieved with width of 80~100 mm and height of 25~35 mm. The insulation layers by EDP process have good adhesion to inner electrode and actuator material as well as have high electrical resistivity, which appear satisfactory in terms of fundamental requirements of multilayer devices. In addition, the vertical EDP fixture setup alleviates the discontinuity problem of deposited lines which was occasionally encountered in the horizontal EDP fixture setup.Though the EDP technique developed in this study proved quite successful, yet it still requires two separate firing routines for densifying insulation layers on even and odd inner electrodes. Furthermore, development of single firing technique was rather essential to practically reduce the production cost and to avoid the unwanted short circuit case due to enhanced diffusion of inner electrode material on the device surface region or among the layers for prolonged firing. The commercial anionic type polymer solution was also used to produce an overcoat onto the end surface of inner electrodes of actuator under 20~25 V/cm electrical field for electrodeposition time of 3~5 sec. The polymer coating was cured at 170oC/0.5h. The tentative polymer overcoat allows to produce insulation layers on both even and odd inner electrodes by EDP process consecutively, which will then be eliminated during the burnout step. The single firing technique developed here will contribute to processing of multilayer piezoelectric actuator and similar multilayer devices in mass production scheme.