| Summary: | 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.
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