Optical Element Edge Region for Stress Management
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Solution Overview
Problem
Stress buildup and reliability issues in optical devices due to differences in coefficients of thermal expansion between material layers and stress caused by polymer crosslinking shrinkage.
Innovation Solution
Incorporating a functional edge region with a reduced edge thickness on the optical element, which extends past the periphery of the optics region, to manage stress distribution and enhance adhesion, thereby reducing stress-induced curvature and delamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two layers of materials with different coefficients of thermal expansion are combined, then the optical device can be made with functional material layers, but stress builds up between the layers leading to curvature and reliability problems
Solution Approach 1:
The patent divides the optical layer into multiple segments: a first optical layer portion directly on the substrate, and a second optical layer portion on top of the first. This segmentation allows different portions of the optical layer to have different thicknesses and stress characteristics, reducing overall stress buildup while maintaining optical functionality.
Solution Approach 2:
The patent applies different thickness characteristics to different regions of the optical layer. The first optical layer portion has a first thickness characteristic while the second optical layer portion has a second thickness characteristic. This local variation in quality allows stress management in specific regions while maintaining optical performance where needed.
2Ease of manufacture
If a cross linkable polymer material layer is placed on a solid substrate, then optical functionality is achieved, but the top layer shrinks during crosslinking causing stress and potential delamination
Solution Approach 1:
The optical layer is segmented into a first portion that can be optimized for adhesion and a second portion that can be optimized for optical functionality. This allows the crosslinking shrinkage stress to be managed by the first portion while the second portion maintains its optical properties.
Solution Approach 2:
The first optical layer portion acts as a cushioning layer that absorbs and distributes the shrinkage stress generated during crosslinking of the polymer material, preventing direct stress concentration at the substrate interface that would cause delamination.
3Adaptability or versatility
If temperature changes occur during device operation, then the device can operate in varying environmental conditions, but stress enhancement occurs leading to crack initiation and delamination
Solution Approach 1:
The segmented optical layer structure creates multiple interfaces that can independently accommodate thermal expansion differences. The first and second optical layer portions can deform differently during thermal cycling, reducing stress concentration and preventing crack initiation.
Solution Approach 2:
The patent changes the physical parameters (thickness characteristics) of different optical layer portions to optimize their thermal response. This allows the structure to better accommodate thermal expansion mismatches between layers with different coefficients of thermal expansion.
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 functional edge region effectively reduces stress within the optical device, enhances reliability by preventing delamination and internal cracking, and allows for the use of materials with higher thermal expansion mismatch without compromising optical performance.
Implementation Method 1
the functional edge region with a reduced edge thickness on the optical element, which extends past the periphery of the optics region, to manage stress distribution and enhance adhesion, thereby reducing stress-induced curvature
Implementation Method 2
the functional edge region with a reduced edge thickness on the optical element, which extends past the periphery of the optics region, to manage stress distribution and enhance adhesion
Implementation Method 3
when combining two layers of materials with different coefficients of thermal expansion (CTE)... temperature changes in device operation, as verified by thermal cycling tests, lead to further stress enhancement
Implementation Method 4
when combining a cross linkable (polymer) material layer on top of a solid substrate material, such as glass, where the top layer shrinks during crosslinking
Data Source
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AI summary
An article includes a substrate having a first surface and a second surface opposite the first surface; and an optical element on the first surface of the substrate, the optical element comprising an optics region. The first surface of the substrate includes an outer region that extends a distance past the periphery of the optics region. A method of making the article and a method of singulating are also disclosed.