Touch Panel Moisture Barrier Layer Design
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Solution Overview
Problem
Touch devices using metal nanowires face reliability issues due to water vapor intrusion through polymer films, leading to electromigration and reduced durability.
Innovation Solution
A touch panel design incorporating a moisture barrier layer and/or adhesive layer with specific material properties to reduce water vapor intrusion and slow down electromigration, featuring a substrate with an electrode, a top coating, and a barrier layer that extends to cover the moisture intrusion interface, using inorganic materials like silicon nitrogen compounds and optically clear adhesives with controlled water absorption and permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer film is used with metal nanowires to produce touch electrodes, then the touch device can be manufactured with flexible transparent conductor, but the polymer film extends to peripheral region causing leakage and allowing water vapor intrusion which reduces reliability
Solution Approach 1:
The device is divided into distinct functional regions: a display region with polymer film and metal nanowires, and a peripheral region with a moisture barrier layer that extends over the polymer film. This segmentation isolates the metal nanowires from direct exposure to moisture at the periphery, preventing electromigration while maintaining the flexible transparent conductor structure in the display area.
Solution Approach 2:
A moisture barrier layer is introduced as an intermediary component between the polymer film and the external environment. This barrier layer blocks water vapor intrusion to the metal nanowires while allowing the polymer film to maintain its electrical and optical functions. The barrier layer acts as a protective mediator that resolves the conflict between using polymer films for flexibility and preventing moisture damage.
2Stability of the object's composition
If polymer film extends to peripheral region to support metal nanowires, then the electrode structure is stabilized, but water vapor easily invades from the polymer film layer causing electromigration
Solution Approach 1:
The moisture barrier layer is formed in advance to cover the polymer film in the peripheral region before moisture intrusion can occur. This preliminary protective action prevents water vapor from reaching the metal nanowires, thereby preventing electromigration while allowing the polymer film to maintain its structural support function.
Solution Approach 2:
Different regions of the device have different material properties: the display region uses polymer film with metal nanowires for electrical conductivity and flexibility, while the peripheral region uses a moisture barrier layer with high water vapor barrier properties. This local differentiation allows each region to optimize its function while protecting against harmful factors.
3Reliability
If moisture barrier layer is added to prevent water vapor intrusion, then reliability is improved, but device complexity increases
Solution Approach 1:
The moisture barrier layer is designed to serve multiple functions: it blocks water vapor intrusion, provides mechanical support at the periphery, and maintains the overall structural integrity of the device. By combining multiple functions into a single layer, the design improves reliability without proportionally increasing complexity.
Solution Approach 2:
The moisture barrier layer is implemented as a thin film structure that is flexible and conformal to the underlying polymer film and substrate. This thin film approach provides effective moisture protection while adding minimal thickness and complexity to the overall device structure.
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 effectively prevents moisture intrusion, thereby enhancing the reliability and longevity of touch devices by reducing electromigration and improving product reliability tests, as demonstrated by passing electrical tests under specific conditions.
Implementation Method 1
a water vapor permeability of the barrier layer can be between 10 g/(m2*day) and 5000 g/(m2*day)
Implementation Method 2
a saturated water absorption of the barrier layer can be between 0.08 wt. % and 0.40 wt. %
Data Source
AI summary
The present disclosure relates to the field of touch technology, and provides a touch display module including a substrate, a transparent conductive layer, a moisture barrier layer, and a display element. The transparent conductive layer is disposed on the substrate. The moisture barrier layer extends laterally on the transparent conductive layer and covers the transparent conductive layer, and the moisture barrier layer includes inorganic materials. The display element is disposed on the moisture barrier layer. The touch display module of the present disclosure can avoid or slow down the water vapor/humidity intrusion from the environment, thereby meeting the specification requirements for improving product reliability test.