Resin Layer Thermal Buffer for Laser Division Cracks in Flexible Displays
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Solution Overview
Problem
The existing manufacturing method for display devices, particularly when dividing the short ring portion, fails to consider the film composition, leading to temperature rises and cracks due to differences in linear expansion coefficients, which can compromise the reliability of the organic EL element by allowing moisture and oxygen penetration.
Innovation Solution
Incorporating a resin layer in the terminal portion region, where lead wiring lines intersect, to mitigate crack formation during the division process, ensuring that at least one of the upper or lower layers in contact with the wiring lines is a resin layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the short ring portion is divided by a laser, then the division process can be completed, but a temperature rise instantaneously occurs in a divided portion causing cracks due to difference in linear expansion coefficient between metal film and inorganic films
Solution Approach 1:
The patent applies local quality by making the resin layer thickness non-uniform: it is thicker at the division line position and thinner at other positions. This localized variation in resin layer thickness provides targeted thermal insulation exactly where the laser division occurs, suppressing temperature rise and crack generation at the critical division site while maintaining overall device functionality
Solution Approach 2:
The patent implements beforehand cushioning by forming a resin layer between the inorganic films before the laser division process. This resin layer acts as a pre-prepared thermal buffer that cushions against the instantaneous temperature rise caused by laser irradiation, preventing thermal shock and subsequent crack formation in the metal film and inorganic films
2Ease of manufacture
If a crack is generated in the terminal portion, then moisture, oxygen, or the like can penetrate into the terminal portion and the organic EL element, but the existing manufacturing method does not consider film composition to prevent this
Solution Approach 1:
The patent employs composite materials by creating a multi-layer structure consisting of inorganic films, metal film, and resin layer. This composite structure combines the advantages of different materials: inorganic films provide barrier properties, metal film provides conductivity, and the resin layer provides thermal insulation and crack prevention. The composite structure inherently protects against moisture and oxygen penetration while enabling reliable laser division
Solution Approach 2:
The patent applies local quality by positioning the resin layer specifically at the division line position within the terminal portion, where it is most needed for crack prevention. This localized placement ensures that the protective function is concentrated where cracks are most likely to occur during division, while maintaining the integrity and protection of the entire terminal portion structure
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 configuration effectively suppresses crack generation at the division site, enhancing the reliability of the terminal portion and the organic EL element by reducing the likelihood of moisture and oxygen ingress.
Implementation Method 1
When the short ring portion is divided by a laser, a temperature rise instantaneously occurs in a divided portion. Thus, when the short ring portion to be divided is formed of a metal film and is sandwiched between an inorganic film in a lower layer and an inorganic film in an upper layer, a crack is more likely to be caused due to a difference in linear expansion coefficient.
Data Source
AI summary
A flexible organic EL display device includes a plurality of short ring wiring lines. Each of the plurality of short ring wiring lines contacts a flattening film that is a resin layer on an end face of a terminal portion region in the flexible organic EL display device.