Fan-Out LED Chip Structure for Compact Full-Color Micro-LED Pixels
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Solution Overview
Problem
Micro-LED displays face challenges due to the small size and fragile nature of micro-LED chips, requiring complex and time-consuming mounting processes, and the need for a large area to achieve adequate brightness, which complicates handling and transfer during manufacturing.
Innovation Solution
A light emitting package with a stacked structure of LED sub-units and a reinforced design that includes connection electrodes and passivation layers, allowing for simplified mounting and enhanced handling by maintaining the growth substrate, reducing the number of chips needed and improving structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are mounted for each sub-pixel on a two-dimensional plane, then color display capability is achieved, but the number of chips required becomes very large, increasing mounting time and complexity
Solution Approach 1:
Multiple LED chips emitting different colors (blue, green, red) are merged into a single stacked structure where the chips are arranged vertically one above another. This stacking approach combines multiple individual chip functions into one integrated unit, reducing the total number of chips from hundreds of thousands to a manageable number while maintaining full color display capability through the vertical arrangement of multi-color sub-units.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement of LED chips to a three-dimensional stacked configuration. By utilizing the vertical dimension, multiple color chips are layered one above another, allowing the system to represent multiple colors simultaneously in a compact footprint. This dimensional change enables efficient use of space and dramatically reduces the number of individual mounting operations required.
2Adaptability or versatility
If sub-pixels are arranged on a two-dimensional plane, then color representation is achieved, but a relatively large area is required, reducing the luminous area and brightness of each sub-pixel
Solution Approach 1:
The patent employs vertical stacking to transition from two-dimensional to three-dimensional space utilization. Multiple color sub-units are arranged in the vertical dimension, allowing each sub-pixel to occupy a compact footprint while maintaining full color representation. This eliminates the trade-off between area and brightness by utilizing the third dimension, thereby preserving luminous area and brightness levels.
Solution Approach 2:
The stacked structure implements a nested arrangement where smaller LED chips emitting different colors are layered one above another within a compact vertical envelope. This nesting approach allows multiple color functions to coexist in a small spatial volume, maintaining the luminous area of each individual sub-pixel while achieving comprehensive color representation through the stacked configuration.
3Ease of operation
If micro-LEDs are singularized into individual chips by cutting the substrate, then individual chip mounting is enabled, but handling becomes difficult due to small size and vulnerable structure
Solution Approach 1:
Multiple individual micro-LED chips are merged into a single stacked assembly that functions as one integrated sub-pixel unit. This merging approach maintains the ability to perform individual chip mounting while protecting the fragile micro-LEDs through their vertical arrangement and shared support structure, thereby reducing handling difficulty despite the small size of each individual chip.
Solution Approach 2:
The patent introduces intermediate structural elements such as support layers and bonding interfaces between the stacked micro-LED chips. These intermediary components provide mechanical support and facilitate handling during the mounting process, protecting the vulnerable micro-LED structure while enabling individual chip operations. The intermediary layers act as mediators that bridge the gap between the fragile micro-LEDs and the external mounting environment.
4Reliability
If electrodes are spaced apart at a pitch corresponding to conventional pixels, then electrical connection is established, but the pitch does not match the reduced size of stacked micro-LED structures
Solution Approach 1:
The patent modifies the electrode pitch parameter to match the reduced dimensions of the stacked micro-LED structure. By adjusting the electrode spacing to correspond to the compact vertical arrangement of multiple chips, the system achieves proper electrical connection while accommodating the smaller overall footprint. This parameter change ensures compatibility between the stacked micro-LED geometry and the electrode layout.
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 enables faster and more efficient manufacturing of micro-LED displays by reducing the complexity of the mounting process, improving chip handling, and maintaining brightness while minimizing the area required for each pixel, thus enhancing the overall efficiency and reliability of micro-LED packages.
Implementation Method 1
protected by passivation layers
Implementation Method 2
Light emitting diodes have been rapidly replacing an existing light source
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.