Cover Glass Shaping via Anisotropic Etching
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Solution Overview
Problem
The high cost of manufacturing touch sensor panels with drive and sense lines formed on both sides of a single substrate is due to the need for protective measures during processing and the expense of flex circuit fabrication and bonding.
Innovation Solution
Performing all processing steps on a substrate sheet before separation, using a removable sacrificial layer and aggressive anisotropic dry etching to create rounded corners or shapes, and applying touch sensor layers before singulation to avoid damaging sensitive layers during bulk shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the substrate is singulated before processing, then the separation step is easier to accomplish, but protective measures are needed during grinding and polishing
Solution Approach 1:
The substrate is singulated before any processing steps are applied. This preliminary separation action eliminates the need for protective measures during subsequent grinding and polishing operations, as each individual substrate is processed independently without risking damage to adjacent areas.
2Productivity
If all processing steps are performed on a substrate sheet before separation, then manufacturing efficiency is improved, but protective measures are required during processing
Solution Approach 1:
The substrate sheet is separated into individual substrates before processing begins. This preliminary singulation enables subsequent processing steps to be performed on each substrate independently without requiring protective measures, while still maintaining manufacturing efficiency through batch processing capabilities.
3Adaptability or versatility
If drive and sense lines are formed on both sides of a single substrate, then touch sensor functionality is achieved, but manufacturing cost increases
Solution Approach 1:
The touch sensor panel is divided into multiple separate substrates, with drive lines formed on the front substrate and sense lines formed on the rear substrate. This segmentation eliminates the need for complex double-sided processing on a single substrate, reducing manufacturing costs while maintaining full touch sensor functionality through the combination of separate front and rear panels.
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 method reduces manufacturing costs and simplifies the process by avoiding the need for protective measures during grinding and polishing, while ensuring the touch sensor panels maintain their sensitivity and cosmetic appeal.
Implementation Method 1
aggressive anisotropic dry etching that etches primarily in the z-direction
Implementation Method 2
The photoresist pattern can be used to define the shape of the cover glass
Implementation Method 3
The rounded corner sacrificial portions can then be etched away to expose the rounded corners of the cover glass
Data Source
AI summary
The fabrication of a touch sensor panel having co-planar single-layer touch sensors fabricated on the back side of a cover glass is disclosed. It can be desirable from a manufacturing perspective to perform all thin-film processing steps on a motherglass before separating it into separate parts. To perform thin-film processing on a motherglass before separation, a removable sacrificial layer such as a photoresist can be applied over the thin-film layers. Next, the motherglass can be scribed and separated, and grinding and polishing steps can be performed prior to removing the sacrificial layer. In alternative embodiments, after the protective sacrificial layer is applied, the bulk of the coverglass can be dry-etched using a very aggressive anisotropic etching that etches primarily in the z-direction. In this embodiment, the etching can be patterned using photolithography to create rounded corners or any other shape. The photoresist can then be removed.