Organic Light Emitting Display Passivation Layer Segmentation for Crack-Free Cutting
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Solution Overview
Problem
Organic light emitting display devices face defects and reduced lifespan due to moisture and foreign material permeation through cracks in the passivation layer formed during the cutting process of mother substrates, which is exacerbated by the use of flexible substrates.
Innovation Solution
The solution involves forming organic light emitting display devices without a passivation layer between adjacent panel regions on a mother substrate, allowing for crack-free cutting and preventing moisture and foreign material ingress, using a flexible polyimide substrate with inorganic passivation layers only on exposed regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed on the entire substrate including between adjacent panel regions, then the substrate is protected from moisture and air permeation, but cracks are generated on the passivation layer during cutting of the mother substrate
Solution Approach 1:
The substrate surface is segmented into different regions: a first region (between adjacent panel regions) where the passivation layer is intentionally not formed to allow clean cutting, and a second region (panel regions) where the passivation layer is formed to protect from moisture and air. This segmentation resolves the contradiction by spatially separating the cutting zone from the protection zone.
Solution Approach 2:
The passivation layer is applied selectively to specific locations on the substrate rather than uniformly across the entire surface. The outer part of the substrate (first region) lacks the passivation layer to enable crack-free cutting, while the display part (second region) has the passivation layer for environmental protection. This local differentiation resolves the contradiction between cutting quality and moisture protection.
2Manufacturing precision
If the passivation layer is removed from the outermost region to prevent cracks during cutting, then crack-free cutting is achieved, but the substrate becomes exposed to moisture and air permeation
Solution Approach 1:
The substrate is divided into functional zones: the outer part (first region) without passivation layer for crack-free cutting, and the display part (second region) with passivation layer for moisture and air protection. This segmentation ensures that the area exposed to cutting processes is different from the area requiring environmental protection.
Solution Approach 2:
The passivation layer presence is differentiated by location: absent in the outer part where cutting occurs to prevent cracks, and present in the display part where protection from moisture and air is needed. This local quality differentiation resolves the contradiction between achieving crack-free cutting and maintaining protection against environmental factors.
3Weight of moving object
If a flexible substrate is used to reduce weight and improve portability, then device portability and flexibility are enhanced, but impurities and foreign materials such as moisture or air easily permeate through the upper substrate
Solution Approach 1:
The flexible substrate receives non-uniform passivation: the outer part remains unprotected (no passivation layer) to maintain flexibility and enable cutting, while the display part is covered with a passivation layer to prevent moisture and air permeation. This local differentiation allows the flexible substrate to simultaneously achieve portability and protection where needed.
Solution Approach 2:
The device uses a composite structure combining the flexible substrate material with an inorganic passivation layer applied selectively on specific regions. This composite approach maintains the inherent flexibility and light weight of the flexible substrate while adding protective properties in the display area through the passivation layer.
Data Source
AI summary
The present disclosure relates to an organic light emitting display device including a substrate having an outer part and a display part, a driving thin film transistor on each of a plurality of pixel regions within the display part of the substrate, a pixel electrode on each pixel region of the display part, an organic light emitting unit on each pixel region of the display part to emit light, a common electrode on the organic light emitting unit and a bank layer to apply a signal to the organic light emitting layer, and a first passivation layer, an organic insulating layer and a second passivation layer on the outer part and the display part, wherein the first passivation layer and the second passivation layer are removed from the outermost region of the outer part, so that the substrate is exposed to the outside.