Stacked Micro-LED Chip Structure for Easier Transfer and Brightness
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Solution Overview
Problem
Micro-LED displays face challenges due to the small size and fragile nature of individual LED chips, requiring complex and time-consuming mounting processes, and the large area required for sub-pixels limits brightness and increases handling difficulties.
Innovation Solution
A light emitting chip with a stacked structure that includes multiple LED sub-units and connection electrodes, where the substrate is not removed, providing a reinforced structure for easier handling and transfer, and a passivation layer to protect the LED stacks during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual micro-LED chips are used for each sub-pixel, then color display capability is achieved, but the number of chips required becomes very large and mounting process becomes complex and time-consuming
Solution Approach 1:
The patent combines multiple LED chips (red, green, blue sub-pixels) into a single integrated micro-LED chip structure. This merging approach maintains the full-color display capability while significantly reducing the number of separate chips that need to be mounted, thereby simplifying the mounting process and reducing complexity.
Solution Approach 2:
The patent transitions from a two-dimensional arrangement of separate LED chips on the substrate to a three-dimensional stacked structure where multiple LED layers are vertically integrated. This dimensional change allows multiple color-emitting elements to be combined in a single chip footprint, reducing the overall number of chips required.
2Adaptability or versatility
If sub-pixels are arranged on a two-dimensional plane, then color display is achieved, but a relatively large area is required which limits luminous area and brightness
Solution Approach 1:
The patent employs vertical stacking of multiple LED layers (red, green, blue) in the third dimension, allowing color display functionality to be achieved within a smaller planar footprint. This three-dimensional arrangement significantly reduces the area required per pixel compared to traditional two-dimensional sub-pixel arrangements.
Solution Approach 2:
Multiple color-emitting LED elements are merged into a single integrated chip structure, consolidating what would traditionally require separate sub-pixels spread across a large area into a compact unified unit, thereby increasing the luminous area density.
3Productivity
If micro-LED chips are cut and transferred individually, then array formation is achieved, but handling becomes difficult due to small size and vulnerable structure
Solution Approach 1:
Multiple LED chips are combined into a single integrated micro-LED chip unit with unified packaging, creating a larger, more robust structure that is easier to handle and transfer compared to individual micro-chips, while still maintaining the capability to form arrays through standard transfer techniques.
Solution Approach 2:
The integrated packaging structure provides mechanical support and protection to the vulnerable LED elements before they undergo transfer processes. This pre-reinforced structure acts as a cushion against handling stresses, preventing damage during manipulation and transfer operations.
4Area of stationary object
If LED chips are made very small to reduce pixel area, then area efficiency is improved, but brightness deteriorates and structure becomes more vulnerable
Solution Approach 1:
The patent compensates for the reduced planar area of miniaturized LEDs by stacking multiple LED layers vertically in the third dimension. This allows the total light-emitting volume to be maintained or increased despite the smaller footprint, thereby preserving brightness while achieving area efficiency.
Solution Approach 2:
Multiple light-emitting elements are merged into a single integrated structure, where the combined light output of multiple LEDs (red, green, blue layers) compensates for the smaller individual chip size, maintaining overall brightness while improving area utilization.
5Area of stationary object
If LED chips are made very small to reduce pixel area, then area efficiency is improved, but handling and transfer become more difficult
Solution Approach 1:
Multiple small LED elements are combined into a single integrated chip unit with unified packaging, creating a larger, more robust structure that is easier to handle and transfer while maintaining the area efficiency benefits of miniaturization.
Solution Approach 2:
The integrated packaging provides structural reinforcement and mechanical protection to the small LED elements before they undergo transfer operations, making them easier to handle without compromising the compact pixel design.
Data Source
AI summary
A light emitting package including a first LED sub-unit, a second LED sub-unit disposed on the first LED sub-unit, a third LED sub-unit disposed on the second LED sub-unit, a plurality of connection electrodes electrically connected to at least one of the first, second, and third LED sub-units, the connection electrodes having side surfaces and covering a side surface of at least one of the first, second, and third LED sub-units, a first passivation layer surrounding at least the side surfaces of the connection electrodes, an insulating layer having first and second opposed surfaces, with the first surface facing the LED sub-units, and a first electrode disposed on the first surface of the insulating layer and connected to at least one of the connection electrodes.