Polymer Overmolded Strengthened Glass Edge Protection
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Solution Overview
Problem
Existing glass articles, despite their strength, are prone to scratches and damage due to their softness, and injection molding processes struggle to combine the benefits of glass with the formability of polymeric materials effectively, especially in creating complex shapes with precise dimensional control.
Innovation Solution
A method involving a shaped glass substrate with a compressive stress layer, coupled with a polymer overmold attached to its perimeter edge, where the glass substrate is either strengthened through tempering or lamination, and the polymer overmold is integrally formed with connectors for attachment, using injection molding with a compliant layer to prevent damage during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass articles are used for their strength, then they resist damage well, but they are prone to scratches and edge damage due to their softness
Solution Approach 1:
The patent combines glass substrate with polymer materials to create a composite structure. The glass provides scratch resistance and structural strength, while the polymer coating protects the edges and surfaces from damage. This composite approach allows the final article to exhibit properties superior to either material alone.
Solution Approach 2:
The patent applies polymer materials to the glass substrate before final assembly, creating a protective cushion layer that absorbs impact and prevents edge chipping. The polymer acts as a pre-applied protective barrier that cushions the glass from harmful forces during use and handling.
2Manufacturing precision
If injection molding is used to form complex shapes, then precise dimensional control is achieved, but combining glass with polymer materials is difficult
Solution Approach 1:
The patent divides the manufacturing process into separate stages: first forming the glass substrate with its complex shape through precision molding, then separately applying the polymer material through injection molding. This segmentation allows each material to be processed optimally without compatibility issues, while achieving precise dimensional control in the final composite part.
Solution Approach 2:
The glass substrate is pre-formed with precise dimensions and complex geometry before the polymer is applied. This preliminary action allows the glass to be molded to exact specifications, and then the polymer is injected to match and complement those pre-established dimensions, achieving precise overall dimensional control.
3Reliability
If glass substrates are strengthened through tempering, then crack propagation is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines the glass strengthening process with the polymer application process. The glass substrate is tempered to prevent crack propagation, and then the polymer is applied in an integrated manufacturing flow. This merging of processes achieves high reliability without proportionally increasing complexity, as the steps are combined into a unified manufacturing sequence.
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 enhances the durability of glass articles by preventing crack propagation and edge damage, allowing for complex shapes with precise control, while combining the benefits of glass and polymer materials for improved strength and formability.
Implementation Method 1
the shaped glass substrate includes a compressive stress layer having a depth of at least 15 microns with a compressive stress of at least 10 MPa
Implementation Method 2
Polymeric material is injected into the injection mold to form the polymer overmold
Implementation Method 3
a compliant layer is disposed between the shaped glass substrate and the first half of the injection mold
Data Source
AI summary
Glass articles for use as covers in electronic devices and methods for forming the same are described herein. The glass articles generally include a shaped glass substrate comprising a first face, a second face and a perimeter edge. The shaped glass substrate may be formed from strengthened glass such that the shaped glass substrate has a compressive stress layer which improves the ability of the glass article to withstand surface damage without cracking. A polymer overmold is coupled to the attachment feature of the perimeter edge of the shaped glass substrate thereby protecting the perimeter edge of the shaped glass substrate from damage. In one embodiment, at least a portion of the perimeter edge of the shaped glass substrate comprises an attachment feature offset from the first face. In another embodiment the polymer overmold is integrally formed with at least one connector.