OLED Pad Electrode Structure for Etching Protection
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Solution Overview
Problem
In organic light emitting diode (OLED) display devices, the pad electrodes are prone to damage during the etching process for forming the anode electrode, leading to potential short circuits and reliability issues due to reaction with etchant chemicals.
Innovation Solution
The introduction of a third pad electrode structure that completely covers the second pad electrode, preventing exposure to etchant chemicals and ensuring electrical connectivity through a stacked electrode configuration, including materials like ITO/Ag/ITO, to protect the underlying electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple pad electrode structure is used, then the device complexity is reduced, but the pad electrodes are prone to damage during etching process
Solution Approach 1:
The pad electrode structure implements a nested configuration where the third pad electrode completely covers the second pad electrode, which in turn covers the first pad electrode. This nested arrangement protects underlying electrodes from etchant chemicals while maintaining electrical connectivity through the stacked configuration.
Solution Approach 2:
The third pad electrode is formed in advance to completely cover the second pad electrode before the etching process for forming the anode electrode. This preliminary protective action prevents the underlying pad electrodes from being damaged by etchant chemicals during subsequent processing steps.
2Reliability
If the third pad electrode completely covers the second pad electrode, then protection from etchant chemicals is achieved, but the device complexity increases
Solution Approach 1:
The pad electrode structure implements a nested configuration where the third pad electrode completely covers the second pad electrode, which in turn covers the first pad electrode. This nested arrangement protects underlying electrodes from etchant chemicals while maintaining electrical connectivity through the stacked configuration.
Solution Approach 2:
The third pad electrode serves multiple functions: it acts as a protective layer for the underlying second and first pad electrodes during etching processes, maintains electrical connectivity through the stacked configuration, and provides a surface for subsequent processing steps. This multi-functionality justifies the additional structural complexity.
3Manufacturing precision
If multiple insulation layers are added to cover lateral portions, then manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The first insulation layer is selectively applied to cover only the lateral portions of the first pad electrode, while the second insulation layer covers the lateral portions of the third pad electrode. This localized insulation approach provides precise protection where needed without unnecessarily complicating the overall structure.
Solution Approach 2:
The insulation structure is segmented into multiple distinct layers: the first insulation layer covering the first pad electrode and the second insulation layer covering the third pad electrode. This segmentation allows for precise control of insulation properties in different regions while maintaining manufacturing feasibility.
Data Source
AI summary
An OLED display device includes a substrate including a display region and a pad region, a display structure in the display region on the substrate, and a pad electrode structure in the pad region on the substrate, the pad electrode structure having a first pad electrode on the substrate, a first insulation layer covering opposite lateral portions of the first pad electrode and exposing a portion of an upper surface of the first pad electrode, a second pad electrode on the first pad electrode and on the first insulation layer, the second pad electrode having a step portion where the first pad electrode and the first insulation layer are overlapped, and a third pad electrode on the second pad electrode and on the first insulation layer, the third electrode covering the second pad electrode.