Flexible Micro-LED Contact Hole Layout for Bend Reliability
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Solution Overview
Problem
Existing display devices, particularly those using inorganic LEDs, face issues with mechanical stress and cracking during bending due to inadequate structural design of contact holes and conductive lines, leading to potential failure of electrical connectivity.
Innovation Solution
The design incorporates a defined distance ratio between bank structures and contact holes, uses conductive lines in zigzag or wave forms, and employs a multilayer arrangement of insulating and protective films, along with a compact micro driver circuit to manage mechanical stress and maintain electrical stability during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If contact holes are positioned close to banks for compact layout, then device area is reduced, but mechanical stress concentration increases causing cracking
Solution Approach 1:
The patent applies local quality by creating a stress relief structure specifically at the contact hole region where mechanical stress concentrates. The recessed portion of the bank is localized exactly where needed (at the contact hole position) to reduce stress concentration, while maintaining the normal bank structure in other areas. This allows compact layout without sacrificing overall mechanical strength.
Solution Approach 2:
The bank structure is segmented into different regions: a recessed portion at the contact hole location and a normal portion elsewhere. This segmentation allows the structure to have different mechanical properties in different locations - the recessed area reduces stress concentration while the normal area maintains structural integrity and compactness.
2Reliability
If rigid conductive lines are used for stable electrical connection, then electrical connectivity is improved, but cracking during bending increases
Solution Approach 1:
The conductive line structure is made dynamic by introducing a bent portion that can deform during bending operations. Instead of a rigid straight line, the conductive line has a controlled bend that allows it to flex with the substrate, maintaining electrical connectivity while accommodating mechanical deformation without cracking.
Solution Approach 2:
The patent changes the geometric parameters of the conductive line by creating a bent portion with specific curvature and position. This parameter change transforms the conductive line from a rigid structure to one that can dynamically adjust its shape, maintaining electrical functionality while improving flexural strength during bending.
3Strength
If multiple layers of insulating and protective films are added for structural integrity, then mechanical strength is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the bank structure itself. The bank serves both as an insulating element and as a mechanical support structure with integrated stress relief features. By combining the insulating function and the mechanical strength function into a single integrated structure, the need for separate protective layers is reduced, simplifying the overall layer structure while maintaining structural integrity.
Data Source
AI summary
The disclosure discloses a display device. The disclosure includes a substrate, a circuit layer on the substrate, and a plurality of banks on the circuit layer. One or more light-emitting elements, each having a first electrode and a second electrode, are disposed one-to-one on the banks. A contact electrode is on the circuit layer, spaced apart from the banks. A first optical layer covers the banks and the light-emitting elements on the banks. A second optical layer covers the first optical layer and includes a contact hole that exposes a portion of the contact electrode. The structure is configured such that, when the distance between the bank and the first optical layer on a surface of the circuit layer is defined as 1, the distance between the first optical layer and the contact hole on the same surface ranges from 0.5 to 2.5, thereby supporting improved structural integrity and reliability.