Glass-Film Laminate Interface for Retained Flexural Strength

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Solution Overview

Problem

The application of thin films to strengthened or strong glass substrates results in a reduction of the average flexural strength, independent of temperature effects or surface damage, due to adhesion and crack bridging between the film and the glass substrate.

Innovation Solution

A crack mitigating layer with a thickness of 1 nm to 10,000 nm, composed of silane, is inserted between the glass substrate and the film to mitigate crack propagation, maintaining the average flexural strength and functional properties of the laminate article.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a film is applied to a strengthened or strong glass substrate, then the glass substrate gains additional functional properties (optical, mechanical, electrical), but the average flexural strength of the glass substrate is reduced due to adhesion and crack bridging

Engineering Contradiction:
Improvefunctional propertiesVSAvoidaverage flexural strength
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

A crack mitigating layer is introduced as an intermediary between the glass substrate and the film. This intermediate layer has lower adhesion to both the glass and the film compared to direct film-to-glass adhesion, allowing cracks to propagate through the intermediate layer rather than bridging between the film and glass substrate, thereby preventing strength reduction while maintaining functional properties

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesion parameters at the interfaces are modified by introducing the crack mitigating layer. The layer creates a gradient in adhesion strength, with the film-to-layer interface having different adhesion characteristics than the layer-to-glass interface, controlling crack propagation paths and preventing catastrophic failure

Inventive Principle:
Principle #35Parameter changes

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 laminate article retains its average flexural strength and functional properties, such as optical and mechanical properties, by deflecting cracks away from the glass substrate, thereby preventing strength degradation.

Implementation Method 1

the reduction in average flexural strength is believed to be associated with the adhesion between such films relative to the strengthened or strong glass substrates

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

crack bridging between such a film and the glass substrate

Methodology Applied
Scientific EffectCrack bridging: Fracture Mechanics

Data Source

PatentEP3872046B1Laminate articles with moderate adhesion and retained strength
Publication Date: 2026.02.18 CORNING INC
  • EP3872046B1 patent drawingFigure 1
  • EP3872046B1 patent drawingFigure 2
  • EP3872046B1 patent drawingFigure 3

AI summary

One or more aspects of the disclosure pertain to an article including a film disposed on a glass substrate, which may be strengthened, where the interface between the film and the glass substrate is modified, such that the article has an improved average flexural strength, and the film retains key functional properties for its application. Some key functional properties of the film include optical, electrical and/or mechanical properties. In one or more embodiments, interface exhibits the effective adhesion energy is about less than about 4 J/m2. In some embodiments, the interface is modified by the inclusion of a crack mitigating layer between the glass substrate and the film.