Organic Buffer Layers for PVD Coated Glass Strength
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Solution Overview
Problem
The application of physical vapor deposition (PVD) coatings to glass substrates in electronic devices reduces the retained bend strength of glass, necessitating a solution to maintain sufficient strength while enhancing appearance and optical properties.
Innovation Solution
Incorporating organic components into a buffer layer between the glass substrate and PVD coatings, or within the PVD layers themselves, to form hybrid materials that increase the retained bend strength of the glass substrates, using materials like SiOCH, TiOCH, or ZrOCH, which provide elastic recovery and resistance to plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PVD coatings are applied to glass substrates, then appearance and optical properties are enhanced, but retained bend strength is reduced
Solution Approach 1:
An organic buffer layer is introduced as an intermediary between the glass substrate and the PVD coating layers. This buffer layer serves as a stress-absorbing interface that prevents the PVD coating from directly weakening the glass substrate, thereby maintaining bend strength while still allowing the appearance-enhancing PVD coating to be applied.
Solution Approach 2:
The patent uses composite material structures combining organic buffer layers with inorganic PVD coating layers. The organic component provides flexibility and stress absorption, while the inorganic PVD layers provide the desired appearance and optical properties, creating a multi-layer composite structure that balances both requirements.
2Ease of manufacture
If coatings are applied to glass layers, then appearance and physical properties are improved, but glass strength is reduced
Solution Approach 1:
The organic buffer layer acts as a mediator that decouples the strengthening effect from the coating application process. It allows the PVD coating to be applied for appearance enhancement while the buffer layer absorbs the stress that would otherwise weaken the glass substrate.
Solution Approach 2:
The patent changes the material parameters of the coating structure by introducing organic materials with different mechanical properties (higher elasticity, lower modulus) between the rigid glass substrate and the PVD coating. This parameter change allows the system to maintain strength while still achieving the desired physical property improvements from the coating.
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 allows glass substrates to retain at least 90% of their original bend strength after coating, improving durability and maintaining transparency, while also enabling decorative and functional layers to enhance the device's appearance.
Implementation Method 1
using materials like SiOCH, TiOCH, or ZrOCH, which provide elastic recovery and resistance to plastic deformation
Implementation Method 2
The organic components may be in a dielectric layer that is part of a physical vapor deposition (PVD) coating
Data Source
AI summary
An electronic device may have a housing surrounding an interior in which electrical components are mounted. A display may be mounted to housing structures in the device. The housing may have a rear wall. The display cover layer and rear wall of the housing may be formed from transparent glass layers. Coatings may be formed on inwardly and/or facing surfaces of the transparent glass layers. A coating on a transparent glass layer may be formed from one or more PVD layers. A buffer layer that includes a hybrid material with an organic component may be interposed between the glass layer and the PVD layers to increase the retained bend strength of the glass layer. Alternatively or additionally, the PVD layers may form a thin-film interference filter, and some of the PVD layers may be formed from the hybrid material to increase the retained bend strength of the glass layer.