Stacked Micro-LED Module Layout for Easier Transfer and Wiring
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Solution Overview
Problem
Micro LEDs are difficult to transfer to a circuit board due to their small size and require a protective structure that prevents optical distortion and luminance loss, while stacked micro LEDs complicate electrical connections.
Innovation Solution
A multilayer structured light emitting device with a specific arrangement of LED stacks and adhesive layers, including micro-optic interfaces and distributed Bragg reflectors, to enhance luminance and simplify the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If micro LEDs are made very small (less than 200μm, further less than 100μm) to achieve high-resolution displays, then display resolution is improved, but transfer difficulty increases significantly
Solution Approach 1:
The patent divides the micro LED structure into separate stacks (first LED stack, second LED stack, third LED stack) with different conductivity types arranged in alternating layers. This segmentation allows each stack to be independently configured and connected, simplifying the transfer process while maintaining high resolution through the stacked arrangement that reduces the lateral space needed for each individual LED element.
Solution Approach 2:
The patent transitions from a planar arrangement of micro LEDs to a three-dimensional stacked structure. By arranging LED stacks vertically in alternating conductivity types with corresponding electrodes positioned between them, the invention utilizes the vertical dimension to achieve high resolution without requiring proportionally smaller lateral dimensions, thereby easing the transfer difficulty associated with extremely small lateral sizes.
2Ease of operation
If stacked micro LEDs are arranged in pixel units on a plane to simplify mounting process, then mounting ease is improved, but electrical connection structure becomes complicated
Solution Approach 1:
The patent segments the electrical connection structure into distinct first and second contact electrodes that are positioned between alternating LED stacks. Each contact electrode connects to multiple LED stacks of the same conductivity type, simplifying the mounting process by allowing standardized connection patterns while maintaining organized electrical pathways through the vertical stack arrangement.
Solution Approach 2:
The patent resolves the electrical connection complexity by moving from a planar connection topology to a three-dimensional vertical connection structure. Contact electrodes are positioned in the vertical space between LED stacks, allowing electrical connections to be made in the vertical dimension rather than requiring complex lateral routing, thereby simplifying the overall electrical connection structure while maintaining pixel-level organization.
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 increases red light luminance, simplifies the device structure, and improves performance and reliability in micro LED displays.
Implementation Method 1
a light extraction efficiency of the first subunit may be increased by forming a micro-optic at a lower surface of the first subunit
Implementation Method 2
a light extraction efficiency of the first subunit may be increased by forming a micro-optic at a lower surface of the first subunit... a distributed Bragg reflector
Data Source
Figure 1A
Figure 1B
Figure 1C~2B
AI summary
A light-emitting device according to an embodiment includes: a substrate; first to third LED stacks disposed on the substrate and each including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a lower insulating layer covering the first to third LED stacks; an upper insulating layer disposed on the lower insulating layer; and electrode pad layers disposed on the upper insulating layer and electrically connected to the first to third LED stacks, wherein the lower insulating layer has openings that allow electrical connection to the first to third LED stacks, the upper insulating layer covers the lower insulating layer such that each of the openings of the lower insulating layer is at least partially exposed, and the electrode pad layers extend on the upper insulating layer and pass through the openings in the lower insulating layer.