Piezoelectric Element Side Electrode Adhesion Design
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Solution Overview
Problem
Piezoelectric elements experience delamination at the side face of the stacked body due to uneven stress distribution, which is exacerbated by increased displacement requirements for greater flexural vibration.
Innovation Solution
A piezoelectric element design featuring a stacked body with internal electrodes extending to the side faces, where secondary electrodes are placed in inter-piezoelectric layer regions to increase adhesion strength and prevent delamination, comprising a bimorph structure with surface and side electrodes for enhanced electrical connectivity and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal electrodes are extended to side faces for electrical connection, then electrical connectivity is improved, but stress concentration and delamination occur at the side faces
Solution Approach 1:
The internal electrode is divided into two distinct parts: a first primary electrode disposed in the inter-piezoelectric layer region and a led-out region extending to the side face. This segmentation allows the electrode to fulfill both electrical connection function and stress distribution function without compromising side face strength
Solution Approach 2:
Different regions of the internal electrode are assigned different functions: the first primary electrode in the inter-piezoelectric layer region provides electrical connectivity, while the led-out region extending to the side face is designed to distribute stress evenly. This local differentiation resolves the contradiction between electrical connection and stress concentration
2Speed
If displacement is increased for greater flexural vibration, then vibration performance is improved, but delamination occurs due to increased stress load
Solution Approach 1:
The patent introduces a second electrode in the inter-piezoelectric layer region that is apart from the led-out region of the first primary electrode. This additional electrode structure acts as a preventive measure to distribute stress before it concentrates at critical points, thereby preventing delamination even when high displacement is required for greater flexural vibration
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
The design effectively suppresses delamination at the side face of the stacked body, enabling stable long-term operation by increasing the adhesion strength between the side face and side electrodes, thus maintaining durability and performance.
Implementation Method 1
the piezoelectric element expands and contracts in a stacking direction when driven to operate
Data Source
AI summary
A piezoelectric element includes: a stacked body in which internal electrodes and piezoelectric layers are laminated; surface electrodes disposed at least on one principal face of the stacked body; and side electrodes disposed on a side face of the stacked body, the internal electrodes extending to the side face, the side electrodes electrically connecting the internal electrodes extending to the side face and the surface electrodes. The internal electrodes each includes a first primary electrode having an active region and a led-out region extending to the side face of the stacked body, the internal electrodes each including a first secondary electrode, the first primary electrodes being disposed in inter-piezoelectric layer regions, the first secondary electrodes being disposed in the inter-piezoelectric layer regions so as to be apart from the led-out regions of the first primary electrodes, and the first secondary electrode is connected to one of the side electrodes.