OLED Pad Electrode Insulation Structure Preventing Metal Scum
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Solution Overview
Problem
In organic light emitting display devices, the formation of metal scum during the patterning of the anode electrode can cause short circuits between the anode and cathode electrodes, leading to dark spots, and the use of organic insulating materials for planarization layers can result in weakened adhesivity of inorganic insulation layers, causing pad electrodes to peel off and fail to transfer signals from driving ICs.
Innovation Solution
The implementation of a structure with a first inorganic insulation layer on both the display and pad areas, a second inorganic insulation layer covering the first pad electrode with an opening, and an organic insulation layer, where the pad electrodes are formed on the same layer as the gate electrodes of transistors, and the anode electrode is patterned with the pad electrodes covered by inorganic insulation layers to prevent metal scum and ensure adhesivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second pad electrode is exposed through an opening in the planarization layer during the patterning process, then the anode electrode can be connected to the driving transistor, but metal scum forms due to the Galvanic effect between the pad electrode metal (e.g., Al) and the anode electrode metal (e.g., Ag), causing short circuits and dark spots
Solution Approach 1:
The patent introduces an inorganic insulation layer as an intermediary between the second pad electrode and the organic insulation layer. This inorganic layer serves as a barrier that prevents direct contact between dissimilar metals (Al and Ag) during the patterning process, thereby eliminating the Galvanic effect and preventing metal scum formation while still allowing electrical connection through the opening.
2Ease of manufacture
If the planarization layer is formed of photosensitive organic material to enable one-time patterning, then manufacturing processes are reduced, but adhesivity of the inorganic insulation layers is weakened, causing detachment and pad electrode peeling
Solution Approach 1:
The patent employs a composite structure consisting of both organic and inorganic insulation layers. The inorganic insulation layer is deposited over the organic planarization layer to provide enhanced mechanical strength and adhesivity. This composite approach maintains the manufacturing efficiency of one-time patterning while compensating for the weak adhesivity of the organic material alone, preventing detachment and pad electrode peeling.
3Productivity
If pad electrodes are formed on the same layer as gate electrodes to reduce manufacturing steps, then production efficiency increases, but the risk of metal scum formation and short circuits increases during subsequent patterning
Solution Approach 1:
The inorganic insulation layer acts as a protective intermediary that covers the pad electrodes formed on the same layer as gate electrodes. This intermediary layer prevents direct exposure of the pad electrodes during subsequent patterning processes, eliminating the risk of Galvanic effect and metal scum formation while maintaining the productivity benefits of reduced manufacturing steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution prevents metal scum formation and short circuits, maintaining the integrity of pad electrodes and ensuring reliable signal transfer by enhancing adhesivity and preventing peeling of pad electrodes.
Implementation Method 1
metal scum may be formed due to the Galvanic effect between the metal (e.g., Al) used for the second pad electrode and the metal (e.g., Ag) used as the material of the anode electrode
Data Source
AI summary
An organic light emitting display device and a method for manufacturing the same is disclosed. The organic light emitting display device comprises a first inorganic insulation layer on a display area and a pad area of a substrate, a first gate electrode and a first pad electrode on the first inorganic insulation layer in the display area and the pad area respectively, a second inorganic insulation layer covering the first gate electrode and a portion of the first pad electrode and having an opening, an organic insulation layer on the second inorganic insulation layer in the display area, a light emitting element on the organic insulation layer, an encapsulation layer covering the light emitting element, a second pad electrode on the second inorganic insulation layer in the pad area and connected to the first pad electrode through the opening.