Asymmetric Laminate Bow Reduction via Thermal Cycling
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Solution Overview
Problem
Asymmetric laminate structures with different coefficients of thermal expansion (CTE) experience out-of-plane distortion, or 'bow,' which can lead to unwanted optical distortion and unsuitable product shapes due to CTE mismatch during the lamination process.
Innovation Solution
A method involving the positioning of an interlayer between substrates with different CTEs, followed by a thermal cycle that includes cooling to a low temperature and subsequent heating to a temperature below the lamination temperature, with controlled ramping rates and holding times, to reduce or eliminate bow in laminate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If asymmetric laminates are made with substrates of different CTEs to achieve aesthetic or structural qualities, then the laminate can provide enhanced damage resistance, structural rigidity, or aesthetic qualities, but the CTE mismatch causes out-of-plane distortion (bow) during cooling that interferes with subsequent processing and results in unwanted optical distortion
Solution Approach 1:
The patent applies preliminary action by performing a thermal cycle treatment before the laminate is used or shipped. The thermal cycle pre-adjusts the internal stresses and CTE mismatch effects while the laminate is still under controlled conditions, thereby reducing bow and preventing distortion during subsequent handling, processing, or installation.
Solution Approach 2:
The patent employs parameter changes by systematically varying temperature parameters during a thermal cycle process. The laminate is subjected to controlled heating and cooling through multiple temperature ranges, which modifies the physical state and stress distribution within the laminate, thereby reducing CTE-induced bow and improving flatness.
2Manufacturing precision
If a thermal cycle process is applied to reduce bow in laminate structures, then the laminate achieves reduced distortion and improved optical performance, but the process requires multiple temperature transitions and holding times that increase processing time
Solution Approach 1:
The patent applies partial action by identifying and implementing the minimum necessary thermal treatment. Rather than exhaustive thermal cycling, the process uses specific temperature ranges and holding times that are sufficient to achieve the desired bow reduction, thereby optimizing the balance between effectiveness and processing time.
Solution Approach 2:
The patent employs periodic action through a structured thermal cycle that involves repeated heating and cooling phases with specific holding times. This periodic temperature variation allows the laminate to progressively relax internal stresses and reduce bow through multiple controlled cycles, achieving distortion reduction while managing processing time.
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 method effectively minimizes bow in laminate structures, allowing for the production of distortion-free or low-bow laminates with a wider range of substrate materials and geometries, improving optical performance and simplifying the manufacturing process.
Implementation Method 1
the first and second substrates have different CTEs... When the laminate structure cools, the CTE mismatch between the substrates can lead to out-of-plane distortion ('bow')
Data Source
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AI summary
Disclosed herein are methods for making asymmetric laminate structures and methods for reducing bow in asymmetric laminate structures, the methods comprising subjecting the laminate structures to at least one thermal cycle comprising cooling the laminate structures to a first temperature near or below room temperature and heating the laminate structures to a second temperature near or below the lamination temperature. Also disclosed herein are laminate structures made according to such methods.