Micro-LED Electrode Contact Structure to Prevent Connection Cracks
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Solution Overview
Problem
The connection between the second electrode and the driving circuit unit in micro light emitting diode display devices is prone to cracks due to the design of the contact hole, which affects the reliability and lifetime of the display device.
Innovation Solution
The display device incorporates a substrate with first and second protrusions on each pixel, where the first electrode is formed on these protrusions, and the second electrode is disposed on the light emitting unit and connected to it. The second electrode is positioned on a second protrusion with a different width in the second direction, and a contact hole with a depth lower than the height of the light emitting unit is formed to connect the second electrode to the driving circuit unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact hole depth is increased to connect the second electrode to the driving circuit unit, then the connection is achieved, but cracks occur in the second electrode
Solution Approach 1:
The patent introduces a protrusion structure as an intermediary element between the second electrode and the driving circuit unit. The protrusion extends from the substrate surface to support the second electrode, serving as a mediator that bridges the connection gap without requiring a deep contact hole that would cause cracking. This intermediary structure distributes the mechanical stress and provides a stable mounting surface for the electrode.
Solution Approach 2:
Instead of solving the connection problem by increasing vertical depth (contact hole depth), the patent transitions to a horizontal dimension solution by extending a protrusion from the substrate. This dimensional shift allows the second electrode to be supported at a shallower depth while maintaining electrical connection to the driving circuit unit through the protrusion structure.
2Strength
If the contact hole depth is reduced to prevent cracks, then electrode integrity is maintained, but connection to the driving circuit unit becomes difficult
Solution Approach 1:
The protrusion acts as a mediator that extends from the substrate to provide support for the second electrode at an optimized depth. This intermediary structure ensures stable electrical connection to the driving circuit unit while maintaining the second electrode at a depth that prevents cracking, thus resolving the contradiction between connection stability and electrode integrity.
3Ease of manufacture
If the contact hole angle deviates from design due to depth variations, then manufacturing flexibility is improved, but crack formation increases
Solution Approach 1:
The protrusion structure serves as a robust intermediary that can accommodate variations in contact hole angle and depth without compromising connection stability. By providing a physical support structure that extends from the substrate, the protrusion ensures the second electrode remains properly positioned and connected even when manufacturing tolerances cause angle deviations, thus decoupling manufacturing flexibility from connection reliability.
Data Source
AI summary
A display device includes a substrate including a display area and a non-display area, a plurality of pixels in the display area, wherein each pixel of the plurality of pixels includes a plurality of sub-pixels, at least one driving circuit unit configured to drive the plurality of pixels, a first protrusion and a second protrusion that are disposed in at least one pixel of the plurality of pixels, a first electrode formed on the first protrusion and the second protrusion, a light emitting unit disposed on the first electrode, and a second electrode disposed on the light emitting unit and connected to the light emitting unit, wherein the first protrusion and the second protrusion may have different widths in a second direction.