Touch Device Silver Nanowire Short Circuit Prevention
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Solution Overview
Problem
Silver nanowires in touch devices are prone to attack by etching liquids during the etching process, leading to short circuits due to poor selectivity and adhesion issues with copper, resulting in the formation of copper-silver crystals.
Innovation Solution
A touch device design featuring a substrate with a touch electrode layer covered by a protective layer having openings that expose the electrode layer, with lead wires formed in these openings extending from the first region to a second region, allowing for conformal formation and direct contact with the substrate, thereby avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper traces are used in direct contact with silver nanowires, then trace formation is enabled, but silver nanowires are attacked by etching liquid causing short circuits
Solution Approach 1:
A protective layer is introduced as an intermediary between the copper traces and silver nanowires. This protective layer is selectively removed at contact regions to enable electrical connection, while maintaining isolation in other areas to prevent etching liquid from attacking the silver nanowires, thus resolving the contradiction between trace formation and short circuit prevention
Solution Approach 2:
The protective layer is designed with spatially varying properties: it is present in most regions to protect silver nanowires from etching liquid, but selectively removed at specific contact regions to allow electrical connection between copper traces and silver nanowires. This local differentiation resolves the contradiction by providing protection where needed and connectivity where required
2Reliability
If copper and silver nanowires are in direct contact, then electrical connection is achieved, but poor adhesion and copper-silver crystal formation occur
Solution Approach 1:
The protective layer serves as a mediator that controls the interface between copper and silver nanowires. By selectively removing the protective layer at contact regions, a controlled interface is created that maintains adhesion while preventing harmful copper-silver crystal formation. The protective layer thus enables reliable electrical connection without the adhesion problems associated with direct copper-silver contact
3Ease of manufacture
If etching liquid is used for trace formation, then copper traces can be formed, but selectivity is low causing silver nanowire attack
Solution Approach 1:
The protective layer acts as a mediator that shields silver nanowires from the etching liquid during copper trace formation. The etching liquid can freely etch copper traces where exposed, while the protective layer prevents it from attacking the silver nanowires, thus enabling copper trace formation without the harmful side effect of silver nanowire degradation
Solution Approach 2:
The protective layer creates local quality differences in the structure: regions with protective layer coverage are resistant to etching liquid, while regions without protective layer allow copper etching. This spatial differentiation enables selective copper trace formation while protecting silver nanowires from attack
Data Source
AI summary
The present disclosure provides a touch device and a manufacturing method thereof. The touch device includes a substrate, a touch electrode layer, a protective layer, and a plurality of wires. The substrate includes a first region and a second region, in which the second region is adjacent to the first region. The touch electrode layer is disposed in the first region and is completely covered by the protective layer. The protective layer has a plurality of openings. The openings expose a portion of the touch electrode layer and extend from the first region to the second region. Each wire is formed in the corresponding openings and extends from the portion of the touch electrode layer to the second region, in which each opening is partially filled with one of the wires, and thereby a recess is defined in each opening.