Auxiliary Electrode Under-cut Void Prevention in Display Devices
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Solution Overview
Problem
In display devices, voids formed between the auxiliary electrode and the bank insulating layer due to inadequate adhesive layer flow in the under-cut region lead to image quality degradation and luminance unevenness, as external moisture can permeate through these voids, affecting the characteristics of thin film transistors.
Innovation Solution
The implementation of a display device design where the under-cut region between the auxiliary electrode and the bank insulating layer is completely filled by an adhesive layer through strategically positioned holes, such as the first and second bank layer holes, allowing the adhesive to extend and fill the gap effectively, preventing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an under-cut region is formed on the auxiliary electrode using a bank insulating layer, then the upper electrode can be electrically connected to the auxiliary electrode, but the adhesive layer cannot sufficiently flow to the under-cut region causing void formation
Solution Approach 1:
The patent divides the under-cut region into multiple segments by forming separate first and second under-cut regions at different locations. This segmentation allows the adhesive layer to flow into each segment independently through respective first and second contact holes, preventing void formation while maintaining electrical connection reliability.
Solution Approach 2:
The patent introduces contact holes as intermediary structures that facilitate adhesive layer flow into the under-cut regions. The first contact hole provides a pathway for adhesive to reach the first under-cut region, and the second contact hole provides a pathway for adhesive to reach the second under-cut region, eliminating voids while preserving electrical connectivity.
2Reliability
If the under-cut region is formed with insufficient adhesive layer flow, then electrical connection is achieved, but external moisture can permeate through voids causing luminance unevenness
Solution Approach 1:
The patent segments the sealing structure into multiple regions with dedicated contact holes, ensuring complete adhesive coverage in each segment. This prevents moisture permeation pathways that would exist in continuous voided regions, while maintaining the electrical connection function through the segmented architecture.
Solution Approach 2:
The patent proactively prevents moisture permeation by ensuring complete adhesive layer coverage in the under-cut regions before moisture can infiltrate. By designing contact holes that enable thorough adhesive penetration into all under-cut regions, the structure preemptively blocks potential moisture pathways, protecting against future luminance unevenness.
3Manufacturing precision
If the adhesive layer is designed to flow into the under-cut region, then voids are prevented, but the structure becomes more complex
Solution Approach 1:
The patent uses segmentation to create multiple smaller under-cut regions with individual contact holes, which is simpler to manufacture than attempting to fill a single large under-cut region. Each segmented portion can be independently addressed by the adhesive layer flowing through its dedicated contact hole, reducing overall structural complexity while achieving complete void prevention.
Data Source
AI summary
A display device capable preventing or reducing luminance unevenness due to a voltage drop using an auxiliary electrode is provided. The display device may include a bank insulating layer that forms an under-cut region for connecting the auxiliary electrode to an upper electrode of a light-emitting structure. The bank insulating layer may include a first bank penetrating hole overlapping with the auxiliary electrode and a second bank penetrating hole spaced apart from the first bank penetrating hole. The second bank penetrating hole may overlap a lower penetrating hole of a lower passivation layer which is disposed between the auxiliary electrode and the bank insulating layer. The lower penetrating hole may overlap the auxiliary electrode.