LED Display Package Substrate Mass Transfer Reliability
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Solution Overview
Problem
The existing methods for fabricating light-emitting diode (LED) displays face challenges such as LED die falling off, shifting, or experiencing non-wetting solder issues during mass transfer, leading to increased complexity in circuit design and reduced area utilization, especially when the size of LEDs is scaled down below 30 μm, making repair and replacement difficult.
Innovation Solution
A light-emitting diode display and method that involves a package substrate with conductive and vacant positions, where LEDs are transferred to a driving backplane, with voltage compensation circuits and integrated circuits to ensure proper electrical connection and voltage generation, allowing for increased light emitting area utilization and reduced transfer times, and improved success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mass transfer is used to transfer many LEDs from growth substrate to driving backplane, then productivity is improved, but reliability deteriorates due to LED die falling off, shifting, or non-wetting solder
Solution Approach 1:
The patent introduces a package substrate as an intermediary carrier between the growth substrate and the driving backplane. The package substrate temporarily holds multiple LED dies during the transfer process, enabling mass transfer while maintaining placement reliability. The package substrate acts as a mediator that facilitates the transfer of multiple LEDs simultaneously without causing falling off, shifting, or soldering issues.
2Area of stationary object
If LED die size is scaled down below 30 μm to increase resolution, then area utilization is improved, but ease of repair deteriorates making repair and replacement difficult
Solution Approach 1:
The patent segments the LED die from the driving backplane by introducing the package substrate as an intermediate layer. This segmentation allows the LED dies to be independently replaced without affecting the driving backplane or other LEDs. The package substrate serves as a removable carrier that enables individual LED replacement even when the LED size is scaled down to below 30 μm, thus maintaining ease of repair while achieving high resolution.
3Ease of repair
If reserved positions are added to driving backplane for repairing failed LED dies, then ease of repair is improved, but device complexity increases and area utilization decreases
Solution Approach 1:
The patent extracts the repair functionality from the driving backplane by moving it to the package substrate level. Instead of adding reserved positions to the driving backplane, the package substrate is designed with replaceable LED dies that can be easily swapped out. This extraction eliminates the need for complex reserved circuit positions on the driving backplane, reducing device complexity while maintaining ease of repair. The package substrate becomes the dedicated repair interface.
Data Source
AI summary
A light-emitting diode display and a method for fabricating the same is disclosed. The light-emitting diode display includes a driving backplane and a plurality of pixel units. Each of the plurality of pixel units includes at least one light-emitting diode and a package substrate. The top surface of the package substrate has at least one conductive position and at least one conductive vacant position corresponding to the at least one conductive position. The conductive position is provided with the light-emitting diode. The conductive position is electrically connected to the light-emitting diode. The bottom surface of the package substrate of each pixel unit is arranged on the driving backplane. The driving backplane is electrically connected to the light-emitting diode and the corresponding conductive vacant position of each pixel unit thereon.