Microprinting Transfer Using LED-Selective Release and Bonding
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Solution Overview
Problem
Current methods for transferring microdevices from a donor substrate to a receiver substrate are inefficient, as they lack precise control over the release and bonding processes, leading to potential misalignment and damage to adjacent devices.
Innovation Solution
A high-resolution LED array is used to selectively release or cure microdevices by focusing light onto a release or bonding layer, allowing for precise control over the transfer process, with a housing structure to minimize light leakage and a holding layer for secure attachment to the receiver substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional transfer method is used to move microdevices from donor substrate to receiver substrate, then the transfer process is simple, but precise control over release and bonding is lost leading to misalignment and damage to adjacent devices
Solution Approach 1:
The transfer process is segmented into distinct phases: release phase (activating release layer), transfer phase (picking up microdevice), and bonding phase (activating bonding layer). Each phase is controlled by selectively activating specific regions of the donor substrate, enabling precise placement while maintaining processability through modular control steps.
Solution Approach 2:
The donor substrate incorporates spatially varying properties: a release layer in the first region that responds to first activation conditions, and a bonding layer in the second region that responds to second activation conditions. This local differentiation enables precise control over when and where microdevices are released and bonded, achieving high placement precision without requiring complex external manipulation.
2Manufacturing precision
If light is used to release or cure the bonding layer, then selective control is achieved, but light leakage to neighbouring microdevices causes interference
Solution Approach 1:
The release layer and bonding layer act as optical intermediaries that are spatially separated and spectrally differentiated. The release layer is designed to respond to first wavelengths while being transparent or insensitive to second wavelengths used for bonding. This intermediary structure allows light to selectively activate only the intended layer without leaking effects to adjacent regions, eliminating cross-interference.
Solution Approach 2:
The optical activation process is segmented into two distinct wavelength regimes: first wavelengths for releasing the release layer and second wavelengths for activating the bonding layer. This spectral segmentation ensures that when light is applied for one function, it does not inadvertently trigger the other function in neighboring microdevices, thereby preventing light leakage interference.
3Manufacturing precision
If higher resolution LED array is used to focus light precisely, then light leakage to neighbouring microdevices is reduced, but device complexity and cost increase
Solution Approach 1:
The patent replaces the need for mechanically complex high-resolution LED arrays with a chemically/biologically based solution: the release layer and bonding layer are designed with specific responses to different wavelengths or conditions. This substitution allows standard LED arrays to achieve selective activation through material design rather than requiring precision engineering of the light source itself, reducing device complexity while maintaining precision.
Solution Approach 2:
The system exploits changes in material parameters (wavelength response, activation thresholds) of the release and bonding layers to achieve selective activation. By tuning the optical or chemical parameters of these layers rather than increasing the resolution of the LED array, the patent achieves precise light focusing and selective control without the complexity and cost of high-resolution LED arrays.
4Productivity
If the release layer is activated to free microdevices, then transfer to receiver substrate is enabled, but bonding to receiver substrate must be precisely controlled
Solution Approach 1:
The transfer process is divided into sequential segments: first, the release layer is activated to free the microdevice from the donor substrate; then, the bonding layer is activated to attach the microdevice to the receiver substrate. This segmentation ensures that release and bonding are independent, controllable steps, allowing high transfer efficiency while maintaining precise bonding control through separate activation triggers.
Solution Approach 2:
The release layer is designed to be activated first as a preliminary action, creating a temporary state where the microdevice is free but not yet bonded. This preliminary release enables subsequent precise positioning and controlled bonding activation, ensuring both high transfer efficiency and precise bonding control by decoupling the release and bonding events in time and space.
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 method enables precise and efficient transfer of microdevices with reduced light leakage and improved bonding, ensuring accurate placement and secure attachment to the receiver substrate, enhancing the reliability of microdevice integration.
Implementation Method 1
The release layer may include a layer converting light to heat causing ablation and pushing the microdevices out of housing toward the receiver substrate
Implementation Method 2
A high resolution display comprising a light emitting device (LED) array may be provided to assist in transferring the microdevices
Implementation Method 3
The LED array can selectively either release a layer by using light or cure a bonding layer
Data Source
AI summary
Embodiments disclose methods of transferring selected microdevices on a receiver substrate. In one embodiment, a high resolution display comprising a light emitting device (LED) array may be provided to assist in transferring the microdevices. The LED array can selectively either release a layer by using light or cure a bonding layer. The pixels in the display can be turned on corresponding to a set of selected microdevices with predefined intensities to release the set of selected microdevices from the donor substrate.