Piezoceramic Multilayer Actuator Electrode Segmentation
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Solution Overview
Problem
The existing methods for manufacturing piezoceramic multilayer actuators are costly and labor-intensive due to the formation of piezoelectrically inactive zones, which lead to mechanical stresses and potential cracks in the layer structure, impairing the actuators' performance.
Innovation Solution
A method involving the production of a multilayer bar in the green state with alternating piezoceramic layers and electrodes, where every second electrode is offset and electrochemically reset, followed by insulation and sintering to create fully active piezoelectric multilayer actuators, reducing manufacturing costs and effort by processing the bar before sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If piezoceramic multilayer actuators are manufactured with layer thicknesses in the range of 100 μm to achieve moderate control voltages, then the control voltage requirement is reduced, but mechanical stresses occur in the transition area to piezoelectrically inactive zones leading to crack formation
Solution Approach 1:
The patent applies segmentation by dividing the electrode structure into active and passive zones. The inner electrodes are designed to extend beyond the piezoceramic layers at the ends, creating distinct active regions (where electrodes are stacked directly) and passive regions (where electrodes are offset). This segmentation allows the actuator to achieve the desired low control voltage through the thin 100 μm piezoceramic layers while the passive zones prevent crack formation by eliminating stress concentrations at the boundaries.
Solution Approach 2:
The patent implements local quality by varying the electrode configuration along the length of the actuator. In the central region, electrodes are arranged in direct stacks to maximize piezoelectric activity and reduce control voltage. At the end regions, electrodes are offset to create passive zones that prevent crack formation. This local variation in electrode quality allows different sections to serve different functions: voltage reduction in the active zone and stress prevention in the passive zone.
2Reliability
If fully active piezoelectric multilayer actuators are used to reduce crack formation, then reliability is improved, but manufacturing complexity increases due to precise electrode alignment requirements
Solution Approach 1:
The patent applies preliminary action by pre-forming the electrode patterns on the piezoceramic green bodies before sintering. The inner electrodes are printed or deposited with precise offset positioning in the green state, and the outer electrodes are applied to the entire surface. This preliminary electrode formation ensures proper alignment and creates the required active/passive zone configuration before the final sintering process, simplifying the overall manufacturing while achieving the complex electrode structure needed for fully active operation.
3Manufacturing precision
If multiple processing steps are performed on sintered multilayer bars to create electrode structures, then electrode precision is improved, but manufacturing cost and effort increase significantly
Solution Approach 1:
The patent implements preliminary action by performing all electrode formation steps on the piezoceramic green bodies before sintering. The inner electrodes are printed or deposited with precise positioning in the green state, and the outer electrodes are applied to the entire surface. This preliminary electrode formation eliminates the need for costly post-sintering processing steps such as electrochemical resetting, mechanical removal, and insulating layer application, significantly reducing manufacturing cost and effort while maintaining electrode precision.
Solution Approach 2:
The patent applies parameter changes by utilizing the different physical and chemical properties of the green body state versus the sintered state. In the green state, the material is softer and more receptive to electrode deposition, allowing precise electrode formation without costly subsequent processing. The sintering process then permanently sets these electrode positions, eliminating the need for expensive post-sintering electrode structure creation steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the simultaneous production of multiple piezoelectric multilayer actuators with reduced mechanical stresses and increased efficiency, lowering production costs by processing the multilayer bar in the green state before sintering, thus minimizing the risk of crack formation and enhancing the actuators' reliability.
Implementation Method 1
Based on the piezoelectric effect, piezoelectric ceramics of suitable crystal structure can expand or contract when an electric field is generated inside them.
Implementation Method 2
Electrically conductive materials are deposited electrochemically on the side surfaces of the electrodes of the same polarity on the individual multilayer structures.
Data Source
Figure 1A~1B
Figure 2~4
Figure 5~7
AI summary
The present invention discloses various production methods for producing a piezoceramic multilayer actuator. In the course of the production method, multilayer locks (10) are electrochemically or mechanically processed in such a way that a recess structure is obtained. The lateral surfaces (22; 24) of the electrodes (20) inside these recesses are electrically insulated using the slip casting method in order to be able to contact the remaining electrodes by imprinting an outer metallization.