Selective Micro Device Transfer by Local Force Modulation
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Solution Overview
Problem
Current methods for selectively transferring micro devices from a donor substrate to a receiver substrate lack precision and efficiency, often resulting in the transfer of unwanted devices due to uniform bonding forces, which hinders the assembly of complex systems like LED displays.
Innovation Solution
A method involving the alignment of donor and receiver substrates, followed by the modulation of forces using techniques such as laser lift-off, heating, adhesive application, mechanical grip, and electrostatic attraction to selectively transfer micro devices, ensuring that only intended devices are transferred by adjusting the donor and receiver forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform bonding forces are applied to all micro devices, then the transfer process is simple, but unwanted devices are transferred along with selected devices
Solution Approach 1:
The patent applies local quality by creating spatially varying bonding forces across the donor substrate. Different regions of the substrate experience different force magnitudes, allowing selected micro devices to be detached while others remain bonded. This is achieved through localized heating zones or variable adhesive distribution, enabling precise control over which devices transfer to the receiver substrate.
Solution Approach 2:
The patent implements dynamics by making the bonding force可调 (adjustable) in both space and time. The donor force can be dynamically modulated during the transfer process, allowing the system to transition from a uniform bonding state to a selective detachment state. This dynamic control enables the transfer process to adapt to different device selection patterns while maintaining overall process simplicity.
2Manufacturing precision
If selective force modulation is applied to transfer only specific micro devices, then transfer precision is improved, but the process complexity increases
Solution Approach 1:
The patent replaces complex mechanical force application systems with thermal or chemical fields. Instead of using multiple actuators to apply mechanical forces to individual devices, the system uses localized heating zones or chemical treatments that naturally create the desired force distribution. This substitution reduces mechanical complexity while achieving the same selective detachment effect.
Solution Approach 2:
The patent implements universality by using a single type of force modulation mechanism (e.g., thermal fields or adhesive control) to handle all selective transfer operations. This multi-functional approach allows the same system to selectively transfer different patterns of micro devices without requiring separate mechanisms for each device type or position, thereby reducing overall process complexity.
3Manufacturing precision
If donor force is weakened for selected micro devices, then transfer selectivity is improved, but bonding strength of remaining devices is reduced
Solution Approach 1:
The patent applies local quality by creating spatially varying bonding forces across the donor substrate. Different regions of the substrate experience different force magnitudes, allowing selected micro devices to be detached while others remain bonded. This is achieved through localized heating zones or variable adhesive distribution, enabling precise control over which devices transfer to the receiver substrate.
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 approach allows for precise and selective transfer of micro devices, enabling the assembly of complex systems like LED displays with improved yield and reduced defects by ensuring only intended devices are transferred, facilitating the integration of micro devices into receiver substrates.
Implementation Method 1
Some embodiments further comprise weakening the donor force using laser lift off.
Implementation Method 2
Some embodiments further comprise weakening the donor force by heating an area of the donor substrate.
Implementation Method 3
In some embodiments the receiver force is generated by electrostatic attraction between the selected micro devices and the receiver substrate.
Implementation Method 4
In some embodiments the receiver force is generated by mechanical grip.
Implementation Method 5
In some embodiments the receiver force is generated by an adhesive layer positioned between the selected micro devices and the receiver substrate.
Data Source
AI summary
A method of selectively transferring micro devices from a donor substrate to contact pads on a receiver substrate. Micro devices being attached to a donor substrate with a donor force. The donor substrate and receiver substrate are aligned and brought together so that selected micro devices meet corresponding contact pads. A receiver force is generated to hold selected micro devices to the contact pads on the receiver substrate. The donor force is weakened and the substrates are moved apart leaving selected micro devices on the receiver substrate. Several methods of generating the receiver force are disclosed, including adhesive, mechanical and electrostatic techniques.