Micro LED Transfer via Electrostatic Attraction
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Solution Overview
Problem
The precision required in transferring micro LEDs from a carrier substrate to a TFT substrate for micro LED display panel manufacturing is challenging due to the small size of the micro LEDs, necessitating improved methods for high-accuracy alignment and bonding.
Innovation Solution
A method involving a carrier substrate with micro LEDs embedded in a decomposable adhesive layer, where electrostatic attraction between the micro LEDs and conductive connecting elements on the TFT substrate allows for precise transfer and bonding, using a conductive solder layer and barrier layers to ensure stable and permanent fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If micro LEDs are transferred from carrier substrate to TFT substrate, then the display panel can be manufactured, but the small size of micro LEDs makes the transfer process difficult to achieve high precision
Solution Approach 1:
The patent introduces a decomposable adhesive layer as an intermediary between the micro LED and the carrier substrate. This adhesive layer can be selectively removed or decomposed, enabling precise release and transfer of the micro LED to the TFT substrate without damaging the fragile micro LED structure. The intermediary layer facilitates controlled transfer while maintaining high precision.
Solution Approach 2:
The patent replaces traditional mechanical transfer methods with electrostatic attraction. Conductive connecting elements on the TFT substrate generate electrostatic forces to attract and precisely position the micro LEDs during transfer, eliminating the need for complex mechanical alignment systems and achieving high precision through field-based control.
2Measurement precision
If traditional transfer methods are used, then the process is simpler, but the alignment and bonding accuracy is insufficient
Solution Approach 1:
The patent replaces complex mechanical alignment systems with electrostatic field-based positioning. Conductive connecting elements on the TFT substrate create electrostatic attraction zones that automatically guide and precisely position micro LEDs during transfer, achieving high alignment accuracy while reducing mechanical complexity.
Solution Approach 2:
The patent utilizes changes in electrostatic field parameters (voltage, field distribution) to control the positioning and bonding of micro LEDs. By adjusting electrical parameters of the conductive connecting elements, precise alignment and stable bonding are achieved without complex mechanical adjustments.
3Stability of the object's composition
If micro LEDs are placed on TFT substrate, then the display function is achieved, but the micro LEDs may move or become unstable without proper fixation
Solution Approach 1:
The decomposable adhesive layer serves as a mediator that provides temporary holding during transfer, then decomposes to allow precise placement. Subsequently, conductive connecting elements provide permanent fixation through electrostatic attraction and physical bonding, ensuring micro LED stability while maintaining manufacturing feasibility.
Solution Approach 2:
The patent replaces mechanical fixation methods with electrostatic bonding through conductive connecting elements. The electrostatic field provides continuous attractive force to secure micro LEDs on the TFT substrate, achieving stable fixation without complex mechanical fastening systems.
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 method enhances the precision and accuracy of micro LED transfer, improving the light emitting efficiency and reliability of the micro LED display panel by ensuring stable and immovable placement of micro LEDs on the TFT substrate.
Implementation Method 1
a first electrode 25 is on an end of each micro LED 20 away from the carrier substrate 10. The micro LEDs 20 are spaced apart from each other and embedded in the adhesive layer 12, which is made of a material decomposable by ultraviolet irradiating or heating, causing non-adhesiveness.
Implementation Method 2
The reference voltage Vref is applied to both the contact electrode layer 54 and the first electrode 25 of the micro LED 20, and the direct current voltage Vdd (different from the reference voltage Vref) is applied to the conductive connecting element 52, causing electrostatic attraction between the first electrode 25 of the micro LED 20 and the conductive connecting element 52 of the TFT substrate 50, the micro LED 20 and the TFT substrate 50 are thus attracted to each other.
Implementation Method 3
a conductive connecting element 52 corresponding to each sub-pixel unit and electrically connected to the driving circuit 51 is formed on the TFT substrate 50... The conductive connecting element 52 is treated so as to bond the first electrode 25 of the micro LED 20.
Data Source
AI summary
A method for making a micro LED display panel not requiring high-accuracy or individual positioning includes providing a carrier substrate with micro LEDs, providing a TFT substrate including a driving circuit, and forming a conductive connecting element, an insulating layer, and a contact electrode layer on the TFT substrate. The insulating layer and the contact electrode layer are patterned to define a through hole, the first electrode is placed against the contact electrode layer, and different voltages Vref and Vdd are applied to the contact electrode layer and to the conductive connecting element respectively, creating an electrostatic attraction. The micro LEDs and the first electrode are transferred from the carrier substrate onto the TFT substrate; and the conductive connecting element is bonded to the first electrode. The method of making is simple. A micro LED display panel made by the method is also provided.