LED Display Panel Buffer Layer for Safe Micro-LED Transfer
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Solution Overview
Problem
Existing methods for transferring small-sized LEDs onto a circuit board in a group face challenges such as difficulty in replacing defective LEDs and potential defects like cracks due to laser lift-off techniques, which affect the safety and efficiency of the transfer process.
Innovation Solution
The use of a buffer material layer between the circuit board and the LEDs, which fills the space between them and includes conductive particles for electrical connection, along with a light blocking material layer to prevent light interference, addresses the issues of safe and efficient LED transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser lift-off technique is used to separate LEDs from growth substrate, then transfer efficiency is improved, but defects such as cracks occur in LEDs due to laser impact
Solution Approach 1:
The patent introduces a release layer as an intermediary between the growth substrate and the LED chips. This release layer absorbs the laser energy and facilitates the separation process without directly exposing the LED chips to high-intensity laser beams, thereby preventing cracks and defects while maintaining efficient transfer
Solution Approach 2:
The release layer is pre-positioned between the growth substrate and LED chips before the laser lift-off process. This beforehand cushioning protects the fragile LED structures from direct laser impact during the separation process, preventing defects before they occur
2Productivity
If sub-pixel area is reduced to fit more sub-pixels in restricted area, then pixel density is improved, but luminous area is reduced deteriorating brightness
Solution Approach 1:
The patent transitions from a two-dimensional arrangement to a three-dimensional stacked structure by placing multiple LED chips vertically on top of each other within the same pixel footprint. This vertical stacking increases the effective luminous area without increasing the horizontal pixel density, thereby maintaining brightness while fitting more pixels in restricted areas
3Ease of repair
If individual small-sized LEDs are mounted on circuit board, then replacement of defective LEDs is simplified, but mounting difficulty increases due to small size
Solution Approach 1:
The patent separates the LED chips from the growth substrate as individual units using the release layer and laser lift-off technique. This segmentation creates discrete, replaceable LED components that can be individually mounted or replaced on the circuit board, simplifying repair while the automated transfer process manages the mounting difficulty
Solution Approach 2:
The release layer is designed to be automatically removed or degraded during the mounting process, allowing the LED chips to self-align and self-attach to the circuit board without complex manual positioning, thereby easing both manufacturing and replacement operations
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
This solution enables safe and efficient transfer of LEDs onto a circuit board, reduces the risk of defects, and improves the brightness of pixels by allowing for a larger sub-pixel area without compromising the structural integrity of the LEDs.
Implementation Method 1
a buffer material layer disposed between the circuit board and the light emitting devices to fill a space between the circuit board and the light emitting devices
Implementation Method 2
the buffer material layer includes conductive particles for electrical connection
Implementation Method 3
a light blocking material layer to prevent light interference
Data Source
AI summary
A display panel including a circuit board having pads, light emitting devices electrically connected to the pads and arranged on the circuit board, each light emitting device having a first surface facing the circuit board and a second surface opposite to the first surface, a buffer material layer disposed between the circuit board and the light emitting devices to fill a space between the circuit board and the light emitting devices, and a cover layer covering the second surface of the light emitting devices, in which the buffer material layer is disposed under the first surfaces of the light emitting devices and has grooves in a region between adjacent light emitting devices, a portion of a top surface of the buffer material layer is disposed between adjacent light emitting devices, and the cover layer fills the grooves of the buffer material layer.