Piezoelectric Transfer Structure for Precise Micro LED Placement
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Solution Overview
Problem
The manufacturing process of micro LED displays faces challenges in efficiently and correctly transferring millions or tens of millions of micron-level micro LED crystalline grains to a circuit substrate.
Innovation Solution
A transfer structure and device are developed, comprising a first electrode, a piezoelectric layer, a second electrode, an adhesion layer, and a position-limiting layer with a cavity, which allows for precise transfer of micro LED crystalline grains by utilizing the inverse piezoelectric effect to extrude and retract the adhesion layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transfer methods are used for micro LED crystalline grains, then the transfer process is simple, but the transfer precision and efficiency are insufficient for millions of micron-level components
Solution Approach 1:
The transfer structure is segmented into distinct functional layers: piezoelectric layer for actuation, adhesion layer for component pickup, and position-limiting layer for precision control. Each layer performs a specific function, enabling precise transfer of micro LED crystalline grains through coordinated operation of these segmented components.
Solution Approach 2:
The adhesion layer serves as an intermediary between the piezoelectric actuator and the micro LED crystalline grain. It temporarily bonds to the component during transfer, then releases it at the target location. The position-limiting layer acts as another intermediary to constrain and guide the component during the transfer process, ensuring precise placement.
2Productivity
If conventional transfer methods are used, then the device structure is simple, but the transfer efficiency for millions of micro LED grains is insufficient
Solution Approach 1:
The adhesion layer is extracted as a separate, removable component from the transfer structure. It can be applied to pickup micro LED crystalline grains and then detached at the target location, enabling efficient transfer without permanently bonding the component to the transfer tool. This extraction principle allows rapid cyclic operation for high-volume transfer.
Solution Approach 2:
The piezoelectric layer utilizes parameter changes in the form of electrical voltage to control adhesion and release. By applying and removing voltage, the piezoelectric material changes its physical state, enabling dynamic control of the adhesion layer's bonding strength. This allows precise timing of pickup and release operations, significantly improving transfer efficiency for large numbers of components.
3Manufacturing precision
If a position-limiting layer with cavity is added to improve transfer precision, then the transfer accuracy improves, but the device complexity increases
Solution Approach 1:
The adhesion layer and piezoelectric layer are nested within the cavity of the position-limiting layer. This nested arrangement allows the functional layers to be contained within the structural framework, achieving precise component placement through the position-limiting layer while maintaining a compact overall structure. The nesting principle reduces spatial requirements and simplifies integration.
Solution Approach 2:
The position-limiting layer introduces a third dimensional constraint through its cavity structure, which physically confines the micro LED crystalline grain during transfer. This dimensional approach to precision control is more effective than two-dimensional planar constraints, enabling accurate placement without requiring overly complex lateral positioning mechanisms.
4Manufacturing precision
If the adhesion layer is made thinner to improve resolution, then the transfer precision improves, but the adhesion strength decreases
Solution Approach 1:
The transfer structure uses composite material principles by combining the piezoelectric layer with the adhesion layer in a layered composite. The piezoelectric layer provides mechanical actuation force, while the adhesion layer provides bonding capability. This composite structure allows the adhesion layer to be thin for precision while the piezoelectric layer compensates for reduced adhesion strength through controlled mechanical forces.
Solution Approach 2:
The patent replaces purely mechanical adhesion systems with a piezoelectrically-controlled system. Instead of relying solely on the mechanical properties of a thick adhesion layer for both strength and precision, the piezoelectric layer provides controlled mechanical actuation that compensates for the reduced strength of a thin adhesion layer, enabling both high resolution and sufficient bonding strength.
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 efficient and precise transfer of micro LED crystalline grains to a circuit substrate, addressing the challenges of handling millions of micron-level components and ensuring accurate placement.
Implementation Method 1
utilizing the inverse piezoelectric effect to extrude and retract the adhesion layer
Data Source
AI summary
Provided in the embodiments are a transfer structure and a method thereof, and a transfer device and a manufacturing method thereof. The transfer structure includes: a first electrode, a piezoelectric layer, a second electrode and an adhesive layer stacked on a substrate in sequence, wherein the first electrode and the second electrode are insulated from each other. The transfer structure further includes: a position-limiting layer, wherein the position-limiting layer includes a cavity; the piezoelectric layer and at least part of the adhesive layer are located in the cavity of the position-limiting layer; and in the direction perpendicular to the substrate, the distance between the surface, away from the substrate, of the position-limiting layer and the substrate is greater than the distance between the surface, away from the substrate, of the adhesive layer and the substrate.