Polyimide-Aluminum Oxide Optical Element Adhesion
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Solution Overview
Problem
Existing optical members with textured aluminum oxide structures face issues of substrate damage, detachment, and cracking due to moisture exposure, and the use of polyimide layers is limited by low adhesiveness and strain stress during the formation of textured structures, leading to instability in antireflection performance over time.
Innovation Solution
A multilayer structure comprising a solvent-soluble polyimide layer with specific repeating units and alkoxysilane groups is introduced between the substrate and the textured aluminum oxide layer, enhancing adhesiveness and affinity, and a fine textured structure of aluminum oxide is formed on the outer surface to achieve stable antireflection performance without cracking or detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a textured structure of boehmite is formed by water vapor treatment or hot water dipping treatment, then excellent antireflection performance is achieved, but the glass substrate may be damaged
Solution Approach 1:
A polyimide layer is introduced as an intermediary between the glass substrate and the textured aluminum oxide layer. This intermediate layer protects the substrate from direct exposure to water vapor and hot water during the texturing process, preventing substrate damage while allowing the formation of the antireflection textured structure.
Solution Approach 2:
The polyimide layer is applied beforehand to cushion and absorb the harmful effects of moisture and vapor during the texturing process. This preparatory protective measure prevents substrate erosion and elution of substrate components before the actual texturing occurs.
2Object-affected harmful factors
If a layer of solvent-soluble polyimide is disposed between the substrate and the textured structure of boehmite, then substrate damage is prevented, but the polyimide layer is low in affinity and adhesiveness to other layers
Solution Approach 1:
The polyimide layer undergoes parameter changes through modification with silane compounds or oxidation treatment, which enhance its surface properties. These modifications increase the affinity and adhesiveness of the polyimide layer to both the substrate and the aluminum oxide layer, resolving the adhesion problem while maintaining the protective function.
Solution Approach 2:
The polyimide layer is combined with other materials such as silane compounds or metal oxides to create a composite structure. This composite approach enhances the adhesiveness and affinity of the polyimide layer to adjacent layers while maintaining its protective function against substrate damage.
3Productivity
If a textured structure of aluminum oxide is formed through hot-water immersion treatment, then high productivity is achieved, but detachment between layers or cracking may occur due to strain stress
Solution Approach 1:
The polyimide layer undergoes parameter changes through crosslinking or reinforcement with other materials, which improve its mechanical strength and strain resistance. This allows the layer to withstand the strain stress generated during hot-water immersion treatment without cracking or detaching, while maintaining high productivity.
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 provides a stable and efficient antireflection effect for a long time, maintaining optical performance and preventing substrate damage, with improved adhesiveness and reduced strain stress, ensuring the antireflection performance is consistent and effective across the visible to infrared regions.
Implementation Method 1
a solvent-soluble polyimide layer having specific repeating units and silane groups introduced therein
Implementation Method 2
enhancing adhesiveness and affinity
Implementation Method 3
an outermost surface having a fine textured structure of a crystal containing aluminum oxide
Implementation Method 4
shows an excellent antireflection performance in a wide wavelength region
Data Source
Figure 1~3
AI summary
Provided is an optical member where at least a layer (2) having polyimide as a main component and a layer (4) having a textured structure (5) arising from a crystal containing aluminum oxide as a main component are stacked in this order. The polyimide includes a silane group in a side chain via an amide bond.