Temperature-Controlled Adhesive Layer for Micro-LED Mass Transfer
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Solution Overview
Problem
The existing mass transfer methods for Micro-LEDs are inefficient and prone to damaging the dies due to electromagnetic fields, limiting the industrialization of high-resolution Micro-LED displays, as they require precise and time-consuming assembly of millions of micron-sized dies.
Innovation Solution
A mass transfer method utilizing a temperature-controlled adhesive layer on a transfer substrate with self-assembling microstructures, allowing for reversible stickiness to facilitate the orderly picking and transferring of Micro-LED dies without electromagnetic interference, and enabling the reuse of transfer substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic transfer is used to pick up and mount Micro-LED dies, then the mounting direction can be controlled, but the Micro-LED dies may be damaged by electromagnetic fields
Solution Approach 1:
The patent replaces the magnetic field-based pickup system with a mechanical adhesion system using a temperature-controlled adhesive layer. The adhesive layer adheres to the Micro-LED dies through thermal activation and releases through cooling, eliminating electromagnetic fields while maintaining precise mounting direction control through the structured transfer substrate.
Solution Approach 2:
The patent changes the physical parameter of the adhesive layer from ambient temperature to temperature-controlled states. By heating the adhesive layer above its transition temperature, it becomes tacky for pickup; by cooling below the transition temperature, it becomes non-tacky for release. This parameter change enables precise die transfer without electromagnetic damage.
2Reliability
If conventional die-bonding methods are used for assembling Micro-LEDs, then the dies can be mounted on the target substrate, but the process takes dozens of days which is too slow for industrialization
Solution Approach 1:
The patent performs preliminary actions by pre-coating the transfer substrate with the temperature-controlled adhesive layer and pre-heating it above the transition temperature before die transfer. This preparation enables rapid die pickup and transfer, reducing the overall assembly time from dozens of days to a much shorter duration suitable for industrialization.
Solution Approach 2:
The patent employs periodic temperature cycling of the adhesive layer - heating above the transition temperature for die pickup and adhesion, then cooling below the transition temperature for die release and transfer. This periodic thermal action enables rapid, repeatable die transfer cycles that dramatically increase productivity while maintaining reliable mounting.
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 significantly improves the efficiency and precision of Micro-LED die transfer, reduces manual operation, and ensures the integrity of the dies by using a temperature-controlled adhesive layer that is sticky above 40°C and non-sticky below 25°C, allowing for precise alignment and separation without damaging the Micro-LEDs.
Implementation Method 1
coating a surface of the self-receiving microstructure with a temperature-controlled adhesive layer; wherein the temperature-controlled adhesive layer is sticky at a temperature higher than 40° C. and loses a sticky property at a temperature below 25° C., and a switch of the sticky property of the temperature-controlled adhesive layer is reversible and repeatable
Data Source
AI summary
A mass transfer method for Micro-LEDs with a temperature-controlled adhesive layer, including: configuring a self-assembling structure based on Micro-LED dies and a transfer substrate having a self-receiving structure coated on its surface with a temperature-controlled adhesive layer; distributing the Micro-LED dies in water, soaking the transfer substrate in water and heating water to perform self-assembling; carrying out transferring and removing the transfer substrate to separate Micro-LED dies from a transfer substrate then onto a target substrate.