LED Display Layer Sealing Against Moisture and Short Defects
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Solution Overview
Problem
Display devices using LEDs face limitations such as moisture permeation and electrical shorts, particularly with reflection plates and conductive components, which affect their reliability and performance.
Innovation Solution
A display device structure is implemented with a substrate having active and non-active areas, featuring inorganic passivation layers, a planarization layer, adhesive layer, and pad electrodes, which minimizes moisture permeation and electrical shorts by sealing the passivation layers and protecting the reflection plates and conductive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED components are used to improve luminance and reliability, then display performance is enhanced, but moisture permeation and electrical shorts occur affecting reliability
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the reflection plate and the second passivation layer. This adhesive layer serves as a barrier that prevents moisture from reaching the reflection plate and conductive components, thereby eliminating the harmful effect of moisture permeation while maintaining the reliability benefits of LED components
Solution Approach 2:
The harmful effect of moisture permeation is extracted and isolated by positioning the adhesive layer specifically at the interface where moisture would otherwise reach the reflection plate. This targeted approach removes the harmful moisture pathway without affecting the overall LED performance and reliability
2Ease of manufacture
If reflection plates and conductive components are disposed adjacent to each other to improve device structure, then manufacturing is simplified, but electrical shorts occur between components
Solution Approach 1:
The second passivation layer acts as an intermediary insulating layer disposed between the reflection plate and conductive components. This layer maintains the simplified adjacent positioning for ease of manufacture while preventing electrical shorts by providing electrical insulation between the conductive elements
Solution Approach 2:
The second passivation layer serves multiple functions simultaneously: it provides electrical insulation to prevent shorts between adjacent reflection plates and conductive components, while also serving as a structural layer in the device architecture. This multi-functionality achieves both ease of manufacture and reliability
3Object-affected harmful factors
If passivation layers are extended to cover pad electrodes area, then moisture protection is improved, but device complexity increases
Solution Approach 1:
The first planarization layer is applied locally only in the area overlapping the pad electrodes, rather than extending across the entire device. This localized application provides moisture protection where it is most needed (at the pad electrode interfaces) while minimizing the increase in device complexity and material usage
Data Source
AI summary
A display device in one example includes a substrate including an active area and a non-active area adjacent to the active area, a plurality of sub pixels disposed in the active area and each including a plurality of transistors, a first passivation layer covering the plurality of transistors, a planarization layer covering the first passivation layer, a second passivation layer covering the planarization layer, an adhesive layer disposed on the second passivation layer, and a plurality of light emitting diodes disposed on the adhesive layer. The first passivation layer and the second passivation contact with each other in the non-active area, so as to seal an end portion of the planarization layer.