Micro-optical Element Bonding Strength via Glass Composition
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Solution Overview
Problem
The challenge in micro-optics is achieving high bonding strength between a glass substrate and a microstructure layer without the time and cost associated with synthesizing acrylic block copolymers, while maintaining stability and consistency in the micro-optical element.
Innovation Solution
A micro-optical element with a glass substrate having specific properties such as high non-bridge oxygen content, low surface roughness, and controlled thickness variation, combined with a microstructure layer formed through imprinting, spin coating, or deposition, to enhance bonding strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acrylic block copolymer is used to bond glass substrate and microstructure layer, then bonding strength is improved, but production cost and synthesis time increase
Solution Approach 1:
The patent replaces expensive acrylic block copolymer with conventional glass materials that are cheaper and easier to manufacture. The glass substrate itself is used as the bonding surface through chemical composition optimization rather than requiring additional polymer materials, thereby reducing production cost while maintaining bonding strength.
Solution Approach 2:
The patent changes the chemical composition parameters of the glass substrate, specifically optimizing the ratio of network formers (SiO2, B2O3) to network modifiers (Na2O, K2O, CaO) to achieve high NBO content. This compositional parameter change enables the glass to inherently provide strong bonding without requiring expensive polymer additives.
2Strength
If glass substrate with high NBO content is used, then bonding strength is improved, but glass composition control difficulty increases
Solution Approach 1:
The patent defines specific parameter ranges for glass composition: SiO2 (60-80 wt%), B2O3 (5-20 wt%), Na2O (8-15 wt%), K2O (5-10 wt%), CaO (5-10 wt%). These parameter specifications provide clear manufacturing targets that balance high NBO content with compositional controllability, ensuring bonding strength while maintaining manufacturing precision.
3Productivity
If glass substrate thickness is reduced, then micro-optical element performance is improved, but bonding strength decreases
Solution Approach 1:
The patent optimizes glass substrate thickness to the range of 50-200 μm, which is thin enough to maintain micro-optical element performance but thick enough to provide sufficient bonding strength. This parameter optimization resolves the contradiction between thinness for performance and thickness for strength.
Solution Approach 2:
The patent creates a composite bonding interface by optimizing the glass chemical composition (high NBO content with specific oxide ratios) to enhance surface reactivity and bonding capability. This composite approach at the material composition level allows thin substrates to achieve strong bonding through enhanced interfacial chemistry rather than relying solely on thickness.
4Manufacturing precision
If glass surface roughness is reduced, then microstructure layer consistency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies surface roughness parameter Ra ≤ 20 nm for the glass substrate. This quantitative parameter control ensures consistent microstructure layer formation during spin coating or deposition while maintaining manufacturability through standard glass polishing and chemical etching processes.
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 achieves a bonding strength greater than 1.5 MPa with reduced delamination risk, even after 1000 cycles at elevated temperature and humidity, and improves the reliability and stability of the micro-optical element for applications in 3D imaging and sensing.
Implementation Method 1
Glass composition with high non-bridge oxygen (NBO) or active oxygen can generate OH—, which can increase the bonding strength with microstructure layer
Implementation Method 2
The microstructure layer formed from polymer is imprinted on the glass substrate
Data Source
AI summary
A micro-optical element is provided that includes a glass substrate, a microstructure layer, and a bonding strength between the glass substrate and microstructure layer. The glass substrate has a thickness of less than or equal to 1500 μm and exhibits a glue contact angle of less than 45°. The microstructure layer is formed from polymer imprinted on the glass substrate. The bonding strength is larger than 0.5 MPa.