Lead Wiring Moisture Barrier for Flexible Displays
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Solution Overview
Problem
In organic EL display devices, moisture from the organic resin film in the frame region can infiltrate into the display region along the surface of the wiring lines, potentially deteriorating the light-emitting layer of the organic EL elements.
Innovation Solution
The display device incorporates a resin substrate with a layered structure of a thin film transistor layer, a light-emitting element layer, and a sealing film. The sealing film is composed of a first inorganic sealing film, an organic sealing film, and a second inorganic sealing film. Lead wiring lines with a specific configuration, including first, second, and third wiring lines made of the same materials but different layers, are used to connect the display region and the bending portion, preventing direct contact and thus blocking moisture infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the organic resin film is provided to be divided into a display region and a frame region to prevent moisture infiltration, then the moisture barrier performance is improved, but moisture can still move along the wiring line surface from the frame region to the display region
Solution Approach 1:
The patent introduces a moisture barrier film as an intermediary layer between the organic resin film and the wiring line. This mediator layer specifically blocks the moisture migration path along the wiring line surface, preventing moisture from moving from the frame region to the display region while maintaining the electrical functionality of the wiring line.
Solution Approach 2:
The moisture barrier film is applied in advance on the wiring line before the organic resin film is formed. This preliminary protective layer preemptively blocks potential moisture infiltration paths, preventing the harmful effect of moisture migration before it can occur during device operation.
2Ease of manufacture
If a single-layer organic resin film is used to cover the wiring line, then the manufacturing process is simple, but moisture can infiltrate into the organic EL elements through the organic resin film
Solution Approach 1:
The patent employs a composite structure consisting of the organic resin film combined with the inorganic moisture barrier film. This composite approach leverages the advantages of both materials: the organic resin film provides flexibility and coverage, while the inorganic moisture barrier film provides superior moisture blocking capability, especially along the wiring line surfaces.
Solution Approach 2:
The protective film structure is segmented into functional layers: the organic resin film for general coverage and flexibility, and the separate moisture barrier film specifically positioned on the wiring line for moisture blocking. This segmentation allows each layer to perform its specialized function effectively.
Data Source
AI summary
Each lead wiring line includes a first wiring line provided on a display region side and formed of the same material and in the same layer as a second metal layer, a second wiring line provided on a bending portion side and formed of the same material and in the same layer as the second metal layer, and a third wiring line provided between the first wiring line and the second wiring line, formed of the same material and in the same layer as the first metal layer and electrically connected to each of the first wiring line and the second wiring line via a first contact hole and a second contact hole formed in an inorganic insulating film.