Stacked LED Chip Structure for Easier Micro-LED Mounting
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Solution Overview
Problem
The challenge in manufacturing micro-LED displays lies in the complexity and time required for mounting hundreds of thousands or millions of small LED chips, which are difficult to handle due to their small size and vulnerable structure, leading to issues during transferring and mounting processes.
Innovation Solution
A light emitting chip with a stacked structure comprising multiple LED sub-units and a passivation layer that protects the structure during transferring, simplifying the mounting process and enhancing handling by providing a stable and protected form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are arranged on a two-dimensional plane for each sub-pixel, then color display capability is achieved, but the number of LED chips required becomes very large (hundreds of thousands or millions), increasing mounting complexity and time
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of individual LED chips to a three-dimensional stacked structure where multiple LED chips are vertically stacked. This dimensional change allows multiple sub-pixels (red, green, blue) to be integrated into a single vertical stack, dramatically reducing the number of chips required and simplifying the mounting process while maintaining full color display capability
Solution Approach 2:
The patent merges multiple individual LED chips (red, green, blue sub-pixels) into a single integrated stacked structure. By combining these chips vertically and connecting them through bonding layers and electrodes, the system achieves the same color display function with fewer discrete components, reducing mounting complexity
2Area of moving object
If micro-LED chips are made very small (surface area of about 10,000 square μm or less) to increase pixel density, then display resolution is improved, but handling becomes difficult due to small size and vulnerable structure
Solution Approach 1:
By merging multiple micro-LED chips into a single stacked structure, the patent creates a larger, more robust unit that is easier to handle than individual micro-chips. The stacked configuration provides structural stability and allows for easier transfer and mounting while maintaining the small footprint needed for high pixel density
Solution Approach 2:
The patent performs preliminary assembly by stacking and bonding multiple LED chips together before the transfer process. This pre-assembly creates a more robust structure with better mechanical strength, making subsequent handling and transfer operations easier compared to manipulating individual micro-chips
3Manufacturing precision
If individual LED chips are used for each sub-pixel, then color accuracy is maintained, but the mounting process requires significant time and complexity
Solution Approach 1:
The patent merges multiple LED chips into stacked structures, reducing the number of separate mounting operations required. Since each stack contains multiple sub-pixels (red, green, blue), fewer individual chips need to be placed and connected, significantly reducing mounting time while maintaining color accuracy through proper optical design and material selection
Solution Approach 2:
By moving from a two-dimensional chip arrangement to a three-dimensional stacked structure, the patent reduces the number of mounting positions required. The vertical stacking allows multiple color sub-pixels to be integrated in the vertical dimension, reducing the horizontal mounting footprint and the overall mounting process time
4Adaptability or versatility
If sub-pixels are arranged on a two-dimensional plane, then color mixing for pixel formation is achieved, but a relatively large area is required for one pixel, reducing luminous area and brightness
Solution Approach 1:
The patent utilizes the vertical dimension by stacking LED chips vertically, allowing multiple color sub-pixels to occupy the same horizontal footprint. This three-dimensional arrangement enables color mixing capability while significantly reducing the horizontal area required per pixel, thereby increasing the luminous area and brightness
Data Source
AI summary
A light emitting chip 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 first bonding layer interposed between the first and second LED sub-units, a second bonding layer interposed between second and third LED sub-units, and a first connection electrode electrically connected to and overlapping at least one of the first, second, and third LED sub-units, the first connection electrode having first and second opposing side surfaces, the first side surface having a first length and the second side surface having a second length, in which the difference in length between the first side surface and the second side surface of the first connection electrode is greater than a thickness of at least one of the LED sub-units.