Light-Emitting Display Bending Area for Metal-Line Crack Reduction
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Solution Overview
Problem
Cracks occur in metal lines of flexible substrates in bending areas of light emitting display panels, deteriorating the quality of the display apparatus.
Innovation Solution
A light emitting display apparatus with a flexible substrate that includes a non-display area with a bending area, where the thickness of the non-display bank and organic material layer in the bending area is smaller than in other areas, and an over-etching process is used to remove tetramethyl ammonium hydroxide (TMAH) and ions (TMA+) to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the flexible substrate is bent in the bending area, then the display apparatus can be folded or curved, but cracks occur in the metal line causing quality deterioration
Solution Approach 1:
The patent applies local quality by making the organic material layer thickness non-uniform: thicker in the bending area to provide cushioning and stress absorption, and thinner in non-bending areas to maintain display quality. This localized variation in material properties allows the structure to accommodate bending without causing metal line cracks while maintaining overall device performance
Solution Approach 2:
The patent implements beforehand cushioning by increasing the thickness of the organic material layer specifically in the bending area before any bending occurs. This pre-positioned thicker layer acts as a cushion that absorbs and distributes stress during bending operations, preventing cracks in the metal line before they can occur
2Reliability
If the organic material layer thickness is increased in the bending area, then crack occurrence is reduced, but the overall structure becomes more complex
Solution Approach 1:
Rather than uniformly increasing the organic material layer thickness throughout the entire substrate (which would significantly increase device complexity), the patent applies local quality by selectively increasing thickness only in the bending area. This targeted approach maintains metal line integrity where needed while keeping the overall structure relatively simple in non-bending regions
3Adaptability or versatility
If the non-display bank thickness is reduced in the bending area, then flexibility is improved, but the protective function may be compromised
Solution Approach 1:
The patent applies local quality by creating a thickness gradient in the non-display bank layer: thinner in the bending area to allow flexibility and stress absorption, and thicker in non-bending areas to maintain protective functions. This localized variation optimizes both flexibility and protection without requiring uniform thickness changes throughout the entire structure
Data Source
AI summary
A light emitting display apparatus can include a flexible substrate, a pixel driving circuit layer, a first planarization layer, a second planarization layer, a first non-display planarization layer, a metal line, a second non-display planarization layer, and a non-display bank. The non-display area includes a bending area to be bent, a connection non-display area included on one side of the bending area and connected to the display area, and a pad non-display area included on another side of the bending area. The thickness of the non-display bank included in the bending area is smaller than the thickness of the non-display bank provided in the connection non-display area and the pad non-display area.