Flexible Display Metal Traces Strain Management
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Solution Overview
Problem
Conventional flexible displays face challenges with metal traces breaking or cracking when bent due to their fracture strain limit, and silicon nitride components being susceptible to cracking, limiting the flexibility and durability of display components.
Innovation Solution
The implementation of a flexible display with serpentine or sine wave-shaped metal traces and a buffer layer with striations in silicon nitride, which are designed to absorb strain and prevent cracking, allowing the display to bend without breaking, and the use of redundant metal traces for added reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal traces are used in flexible displays, then electrical conductivity is improved, but the traces break or disconnect when the display is bent due to fracture strain limit
Solution Approach 1:
The patent applies serpentine or sine wave-shaped metal traces instead of straight lines. This curved geometry allows the traces to flex and deform elastically when the display is bent, distributing stress along the curved path and preventing fracture while maintaining electrical conductivity throughout the flexible display structure.
Solution Approach 2:
The patent changes the geometric parameters of the metal traces by introducing serpentine or sine wave patterns with specific wavelengths and amplitudes. These parameter changes enable the traces to accommodate bending strains that would otherwise cause failure, transforming rigid straight conductors into flexible pathways that maintain connectivity during deformation.
2Ease of manufacture
If silicon nitride is used in display components, then manufacturing is improved, but the components are susceptible to cracking when bent
Solution Approach 1:
The patent segments the continuous silicon nitride layer into multiple smaller regions separated by gaps or trenches. This segmentation prevents crack propagation through the entire layer, as cracks are confined to individual segments and cannot traverse the full distance, thereby maintaining structural integrity during bending while preserving the manufacturing advantages of silicon nitride.
Solution Approach 2:
The patent extracts or removes portions of the silicon nitride layer to create gaps or trenches between functional regions. This extraction eliminates the continuous stress path that would lead to catastrophic failure, allowing the display to flex without cracking while still utilizing silicon nitride's beneficial manufacturing properties in the remaining segments.
3Adaptability or versatility
If organic materials are used for display components, then flexibility is improved, but electrical conductivity is reduced compared to metal traces
Solution Approach 1:
The patent employs composite material structures combining organic flexible substrates with metal trace patterns. This composite approach leverages the flexibility of organic materials for the substrate and interconnect structures while using metal inlays or patterns to provide the necessary electrical conductivity, achieving both flexibility and conductive performance in the same component.
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
The solution enhances the flexibility and durability of the display, enabling it to be rolled or bent into non-planar shapes without cracking, thereby improving portability and operational capabilities while maintaining electrical conductivity.
Implementation Method 1
At least one of the first plurality of metal lines and the second plurality of metal lines comprises a non-stretchable portion in the TFT areas and a stretchable portion outside the TFT areas
Implementation Method 2
The buffer layer outside the TFT area is configured to have a striation pattern
Data Source
AI summary
A flexible display having an array of pixels or sub-pixels is provided. The display includes a flexible substrate and an array of thin film transistors (TFTs) corresponding to the array of pixels or sub-pixels on the substrate. The display also includes a first plurality of metal lines coupled to gate electrodes of the TFTs and a second plurality of metal lines coupled to source electrodes and drain electrodes of the TFTs. At least one of the first plurality of metal lines and the second plurality of metal lines comprises a non-stretchable portion in the TFT areas and a stretchable portion outside the TFT areas.