Piezoelectric Substrate Bonding Pattern Segmentation
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Solution Overview
Problem
Conventional piezoelectric element substrates face issues with crater-like defects during organic peeling cleaning, leading to defective bonding and reduced yield due to surface erosion and increased film stress, which affects the bonding strength and reliability of the actuator substrate.
Innovation Solution
A piezoelectric element substrate with a metal layer featuring a bonding pattern having multiple slots instead of a solid film in the bonding region, reducing the area of the metal layer and preventing crater-like defects, thereby enhancing bonding strength and reducing film stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a solid film bonding pattern with relatively large area is used, then bonding coverage is improved, but crater-like defects occur during cleaning leading to defective bonding
Solution Approach 1:
The bonding pattern is divided into multiple separate bonding regions instead of a continuous solid film. These discrete bonding regions maintain sufficient total bonding area while eliminating the large continuous surface that causes crater-like defects during cleaning, thus resolving the contradiction between bonding coverage and bonding quality
Solution Approach 2:
Different regions of the metal layer are given different functions: wiring patterns for electrical connection and discrete bonding patterns for mechanical bonding. This local differentiation allows the bonding regions to be optimized for bonding quality (smaller, discrete areas) while maintaining sufficient total bonding area through strategic placement
2Area of stationary object
If a solid film bonding pattern is used, then bonding area is increased, but film stress increases leading to peeling
Solution Approach 1:
The continuous bonding pattern is segmented into multiple discrete bonding regions. This segmentation reduces the cumulative film stress by breaking the continuous stress distribution, while the total bonding area is maintained through optimized arrangement of the discrete regions, preventing film peeling
Solution Approach 2:
Instead of using a minimal bonding pattern, the invention uses multiple discrete bonding regions that collectively provide sufficient bonding area. This partial distribution of bonding function across multiple regions reduces stress concentration while achieving adequate total bonding capability
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 solution prevents film peeling and ensures higher yield by maintaining a smooth bonding surface and increasing bonding strength between the metal wiring layer and the subframe, improving the reliability of the actuator substrate.
Implementation Method 1
The upper and lower electrodes are applied with a voltage to cause the piezoelectric body as an electromechanical transducer film to deform
Data Source
AI summary
A piezoelectric element substrate is provided. The piezoelectric element substrate includes: a substrate member; a plurality of piezoelectric elements on the substrate member; a plurality of wiring patterns on one side of the substrate member on which the plurality of piezoelectric elements is disposed; and a bonding pattern in a region different from the wiring patterns on the one side of the substrate member. Each of the piezoelectric elements includes a first electrode, a piezoelectric body, and a second electrode. The wiring patterns are connected to the corresponding piezoelectric elements. The bonding pattern is to be bonded to another substrate directly or via an insulating film, and is made of a metal layer having a plurality of slots.