Closed Magnetic Circuit for Uniform Micro-LED Pickup Force
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Solution Overview
Problem
Current pick-and-place devices struggle to efficiently transfer and handle micro-LED devices due to size limitations, damage from vacuum pressure, and non-uniform magnetic suction forces, which complicates high-resolution micro-LED display manufacturing and increases costs.
Innovation Solution
A magnetic transfer apparatus with a closed magnetic circuit using a single magnetomotive force source and binary tree structured magnetic flux distribution circuits to provide uniform magnetic suction force across multiple LED devices, allowing for precise and simultaneous transfer of micro-LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single magnetomotive force source is used in a closed magnetic circuit, then manufacturing complexity and cost are reduced, but achieving uniform magnetic suction force across multiple LED devices becomes difficult
Solution Approach 1:
The magnetic circuit is segmented into multiple branches, each terminating at a different position around the magnetomotive force source. This segmentation allows uniform magnetic suction force to be achieved at multiple pickup locations while using a single magnetomotive force source, resolving the contradiction between manufacturing simplicity and uniformity of magnetic force.
Solution Approach 2:
The magnetic circuit is designed with branches having different lengths and configurations to provide locally optimized magnetic flux distribution. Each branch is tailored to deliver uniform magnetic suction force at its specific termination point, enabling precise pickup of LED devices at multiple locations while maintaining overall system simplicity.
2Ease of manufacture
If vacuum adsorption is used to pick up micro-LED devices, then the picking process is simple, but the devices may be damaged by vacuum pressure
Solution Approach 1:
The vacuum mechanical picking system is replaced with a magnetic field-based pickup system. Magnetic force is used to attract and hold micro-LED devices containing magnetic particles, eliminating the need for vacuum pressure and associated damage risks while maintaining picking effectiveness.
Solution Approach 2:
The pickup mechanism transitions from pressure-based (vacuum) to field-based (magnetic). By changing the fundamental parameter from mechanical pressure to magnetic field strength, the system achieves gentle handling of micro-LED devices without compromising pickup capability.
3Manufacturing precision
If magnetic particles are dispersed in photoresist to form magnetic alignment axis, then magnetic field can be localized to specific regions, but gas bubbles form and require 12 hours to remove
Solution Approach 1:
The problematic photoresist medium containing magnetic particles is extracted and replaced with a direct magnetic circuit structure. Magnetic particles are embedded in non-magnetic layers within the magnetic circuit itself, eliminating gas bubble formation and long waiting times while preserving magnetic field localization capability.
Solution Approach 2:
Non-magnetic layers serve as intermediaries to embed and position magnetic particles precisely within the magnetic circuit structure. This intermediary approach enables controlled magnetic particle placement without the drawbacks of dispersing particles in photoresist, achieving both localization and process efficiency.
4Adaptability or versatility
If magnetic particles are used for pickup, then magnetic field can be applied selectively, but particles must be used within 48 hours or they agglomerate
Solution Approach 1:
Magnetic particles are pre-loaded into the magnetic circuit structure during manufacturing, forming a stable, long-lasting magnetic pickup system. This preliminary action eliminates the need for frequent replacement of magnetic particles, extending the operational lifetime from 48 hours to the lifetime of the device itself while maintaining selective magnetic field application capability.
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
Enables efficient and uniform transfer of micro-LED devices with reduced risk of damage, improving manufacturing yield and reducing costs by ensuring consistent magnetic suction force across all devices.
Implementation Method 1
a magnetomotive force source providing magnetic flux
Implementation Method 2
distributing the magnetic flux provided by the magnetomotive force source
Implementation Method 3
pick up a plurality of LED devices by distributing magnetic flux through a first magnetic flux distribution circuit and a second magnetic flux distribution circuit using a single magnetomotive force source such that respective branches provide the same magnetic suction force
Data Source
AI summary
A magnetic transfer apparatus includes: a magnetomotive force source providing magnetic flux, a first magnetic flux distribution circuit connected to one end of the magnetomotive force source, having a single input terminal and a plurality of output terminals, and distributing the magnetic flux, and a second magnetic flux distribution circuit connected to the other end of the magnetomotive force source, having a single output terminal and a plurality of input terminals, and collecting the distributed magnetic flux. The output terminals of the first magnetic flux distribution circuit are disposed to be adjacent to each other to form a pair with the input terminals of the second magnetic flux distribution circuit.