Flexible Substrate Stress Modification for Defect-Free Curving
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Solution Overview
Problem
Existing methods for modifying the stress state of active layers in microelectronics and related fields face challenges in achieving high deformation without creating defects, particularly when using substrates with high stiffness, which can lead to difficulties in curving and assembling without causing defects, especially for large dimensions.
Innovation Solution
A method involving a first substrate with an active layer and a second flexible substrate with a significantly thicker thickness ratio (h2/h1 ≥ 10^4) and a lower Young's modulus (E2/E1 < 10^-2), allowing for predetermined curvature and assembly to achieve high stress levels in the active layer without defects, using elastomers and reinforcement members to enhance flexibility and mechanical reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a second substrate with high stiffness (E2 ≈ E1) is used to achieve the required stress state, then the stress state can be modified, but the substrate becomes difficult to curve without causing defects
Solution Approach 1:
The patent changes the key parameter from substrate stiffness matching (E2 ≈ E1) to thickness ratio control (h2/h1 ≥ 10^4). By using a thin second substrate with much smaller thickness than the active layer, the substrate can be easily curved while still providing the necessary stress state modification when restored to its initial shape.
Solution Approach 2:
The second substrate is designed as a thin film structure with thickness h2 satisfying h2/h1 ≥ 10^4. This thin film configuration enables the substrate to be flexed and curved during the manufacturing process without causing defects, while still functioning effectively in stress state modification.
2Ease of operation
If the thickness ratio h2/h1 is increased to improve flexibility, then curving becomes easier, but the stiffness E2 must be sufficiently low to maintain the relationship E2/E1 < 10^-2
Solution Approach 1:
The patent establishes a dual-parameter relationship: thickness ratio h2/h1 ≥ 10^4 and stiffness ratio E2/E1 < 10^-2. These parameter changes work together to achieve both high flexibility for easy curving and appropriate mechanical properties for effective stress state modification.
3Force
If a thick second substrate is used to provide sufficient torque for curving, then curving capability improves, but the substrate becomes difficult to assemble without defects
Solution Approach 1:
The second substrate is designed as a thin film with thickness h2 satisfying h2/h1 ≥ 10^4. This thin film configuration provides sufficient flexibility to conform to the arcuate shape during assembly while minimizing the risk of defects, replacing the need for thick substrates that would provide torque but compromise assembly precision.
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 enables deformation greater than 0.75% or 1% in the active layer without defects, improving electronic and electromagnetic properties by modifying the stress state effectively, while also addressing warping issues and enhancing piezoelectric transduction efficiency.
Implementation Method 1
curving the first substrate and the second substrate so that they each have an arcuate shape with a substantially identical radius of curvature denoted R
Implementation Method 2
restoring the initial shape at rest of the second substrate so that the active layer has the final stress state
Data Source
Figure 1a~1d
Figure 1e~1g
Figure 2a~2b
AI summary
This method comprises the steps of a) providing a first substrate (1) comprising the active layer (10) made from a first material with Young's modulus E1, and thickness h1; b) providing a second substrate (2) made from a second material with Young's modulus E2, and thickness h2, c) bending the first substrate (1) and the second substrate (2) in such a way that each has an arched shape having radius of curvature R; d) assembling the second substrate (2) to the active layer (10) in such a way that the second substrate (2) conforms to the shape of the first substrate (1 ); e) restoring the initial shape, at rest, of the second substrate (2), the method being remarkable in that the second material of the second substrate (2) is a flexible material that satisfies the equation E2/E1 < 10-2, in that the thickness of the second substrate (2) satisfies the equation h2/h1≥ 104, and in that the radius of curvature satisfies the equation R = h2/2ε.