In-Cell Touch OLED Adhesive Overflow Control
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Solution Overview
Problem
In touch organic light-emitting display devices, the adhesive layer often overflows to pad electrodes, causing contact failures and damaging flexible substrates during the bonding process, leading to operational defects and reliability issues with wires.
Innovation Solution
The implementation of concave patterns and dams on the upper and lower substrates controls the flow of the adhesive layer, preventing overflow and ensuring even distribution, thereby enhancing the reliability of pad portions and wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive agent is applied to bond lower substrate and upper substrate, then bonding strength is improved, but adhesive agent overflows to pad electrodes causing contact failure
Solution Approach 1:
The pad electrode area is segmented from the bonding area by introducing a recessed pattern. This recessed pattern creates a physical boundary that segments the adhesive application zone, allowing adhesive to be confined to non-pad regions while still providing adequate bonding coverage in the display area.
Solution Approach 2:
The recessed pattern creates local quality differences in the substrate surface. The recessed areas provide localized adhesive retention zones with different surface properties compared to the surrounding flat areas, enabling controlled adhesive distribution that prevents overflow onto pad electrodes while maintaining bonding effectiveness.
2Strength
If adhesive agent is applied to bond substrates, then bonding is achieved, but adhesive overflow damages flexible substrate during laser irradiation removal
Solution Approach 1:
The recessed pattern segments the adhesive application area, creating defined boundaries that prevent adhesive from reaching flexible substrate regions. This spatial segmentation ensures that even with excessive adhesive application, the material is confined to specific zones away from the flexible substrate edges that would be exposed to laser irradiation.
Solution Approach 2:
The recessed pattern acts as an intermediary structure between the adhesive agent and the flexible substrate. It serves as a buffer zone that intercepts excess adhesive before it can reach the flexible substrate, thereby protecting the substrate from adhesive-related damage during subsequent laser irradiation processes.
3Area of stationary object
If adhesive agent is applied in excess to ensure coverage, then bonding coverage is improved, but adhesive directly bonds to substrates making removal impossible
Solution Approach 1:
The recessed pattern segments the substrate surface into adhesive-retention zones and adhesive-exclusion zones. This segmentation allows excess adhesive to be contained within the recessed areas where it can cure without forming direct bonds to the main substrate surfaces, thereby maintaining ease of substrate removal while ensuring adequate coverage in bonding regions.
Solution Approach 2:
The recessed pattern creates local quality variations in adhesive distribution. In the recessed zones, adhesive is concentrated and contained, providing sufficient coverage for bonding purposes. In the surrounding flat zones, the pattern prevents adhesive accumulation that would lead to direct substrate bonding, thus maintaining manufacturability and substrate removability.
Data Source
AI summary
A touch organic light-emitting display device includes: a substrate including: a display area, and a non-display area, a lower base crossing the display area and the non-display area, an upper base opposite the lower base, the upper base crossing the display area and the non-display area, an adhesive layer between the lower base and the upper base, and a pad portion in the non-display area, wherein the upper base includes a plurality of concave patterns and at least one upper dam at a position corresponding to a region between the pad portion and the display area.