Composite Piezoelectric Substrate Bonding to Suppress Warp
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Solution Overview
Problem
Existing methods for producing composite substrates for piezoelectric actuators face issues such as warp occurrence, reduced yield, and difficulty in achieving low-voltage-driven actuators with high displacement, while also raising concerns about high-temperature reliability due to the use of organic adhesives.
Innovation Solution
A composite substrate is developed with a support substrate and a piezoelectric film containing a non-oriented polycrystalline substance with a c-axis orientation of 80% or less, a joining layer with an amorphous substance, and an electrode structure, which includes an argon-containing amorphous layer to suppress warp and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric element with high c-axis orientation is used, then piezoelectric performance is improved, but warp occurrence increases and yield decreases
Solution Approach 1:
The patent changes the orientation parameter of the piezoelectric film from high c-axis orientation (80% or more) to low c-axis orientation (80% or less), thereby reducing internal stress and preventing warp occurrence while maintaining adequate piezoelectric performance for the application
2Ease of manufacture
If adhesive is used to join piezoelectric body and support substrate, then assembly is simplified, but high-temperature reliability deteriorates
Solution Approach 1:
The patent removes the adhesive layer from the structure, joining the piezoelectric film directly to the support substrate through direct bonding, thereby eliminating the reliability issues associated with organic adhesives at high temperatures while maintaining manufacturing simplicity
Solution Approach 2:
The patent creates a composite structure where the piezoelectric film and support substrate are directly bonded, forming an integrated composite material system that eliminates the need for separate adhesive materials and improves high-temperature reliability
3Use of energy by moving object
If piezoelectric body thickness is reduced for low-voltage operation, then actuator voltage requirement decreases, but structural stability and warp resistance deteriorate
Solution Approach 1:
The patent changes the orientation parameter of the piezoelectric film from high c-axis orientation (80% or more) to low c-axis orientation (80% or less), thereby reducing internal stress and preventing warp occurrence while maintaining adequate piezoelectric performance for the application
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 effectively suppresses warp occurrence, allows for the production of low-voltage-driven piezoelectric actuators with high displacement, and improves the reliability of the composite substrate by maintaining structural integrity at high temperatures without the need for organic adhesives.
Implementation Method 1
A piezoelectric actuator that vibrates an electro-mechanical conversion film
Data Source
AI summary
A composite substrate includes: a support substrate; a piezoelectric film arranged above the support substrate; and a joining layer arranged between the support substrate and the piezoelectric film, wherein the piezoelectric film includes a polycrystalline substance having a degree of c-axis orientation determined by a Lotgering method of 80% or less, and wherein the joining layer includes an amorphous substance.