Micro LED Transfer Device Using Dual-Wavelength Laser Bonding
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Solution Overview
Problem
Current micro LED transfer processes face inefficiencies in precise positioning and bonding, leading to non-uniform output characteristics and increased manufacturing time due to limitations in existing alignment and bonding methods.
Innovation Solution
A micro LED transfer device and method utilizing a relay substrate with a mask, first and second lasers of different wavelengths, and a processor to control the transfer process, ensuring precise alignment and bonding of micro LEDs on a target substrate, using a coupling layer and adhesive layer to achieve uniform output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a micro LED is transferred to a target substrate using conventional methods, then the micro LED can be positioned on the substrate, but the positioning precision and bonding uniformity are insufficient leading to non-uniform output characteristics
Solution Approach 1:
The patent introduces a relay substrate as an intermediary carrier between the wafer and the target substrate. The micro LEDs are first transferred to the relay substrate where they can be precisely positioned using a mask alignment system, then subsequently transferred to the target substrate. This two-stage transfer process with relay substrate as mediator enables both high positioning precision and efficient mass transfer.
Solution Approach 2:
The transfer process is segmented into multiple stages: (1) transferring micro LEDs from wafer to relay substrate with precise mask alignment, (2) positioning micro LEDs on relay substrate at predetermined intervals, and (3) transferring from relay substrate to target substrate. This segmentation allows each stage to be optimized independently for precision and efficiency.
2Reliability
If conventional bonding methods are used to attach micro LEDs to the target substrate, then bonding can be achieved, but the process time is increased and output characteristics are non-uniform
Solution Approach 1:
The patent employs laser irradiation to change the physical state of the coupling layer material, transforming it from a solid adhesive layer to a molten state that enables precise bonding. By controlling laser parameters (wavelength, power, duration), the bonding process achieves both high quality and uniformity while reducing process time compared to conventional thermal or mechanical bonding methods.
Solution Approach 2:
The patent replaces conventional mechanical or thermal bonding methods with laser-based bonding. The laser irradiation system substitutes for traditional heating elements or pressure applying mechanisms, enabling more precise and faster bonding control through optical energy delivery.
3Productivity
If multiple micro LEDs are transferred simultaneously to improve efficiency, then transfer speed increases, but alignment precision and positioning accuracy deteriorate
Solution Approach 1:
The relay substrate serves as an intermediary that enables simultaneous transfer of multiple micro LEDs while maintaining precision. The mask alignment system on the relay substrate provides reference markers that allow multiple LEDs to be positioned accurately at predetermined intervals during a single transfer operation, then the entire array can be transferred to the target substrate together.
Solution Approach 2:
The micro LEDs are preliminarily positioned on the relay substrate with precise alignment using the mask system before the final transfer to the target substrate. This preliminary positioning establishes accurate relative positions among multiple LEDs, which are then maintained during the subsequent transfer process, enabling both high speed and high precision.
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 enhances transfer efficiency, reduces manufacturing time, and ensures uniform output characteristics across micro LED arrays, improving the brightness and color consistency of micro LED displays.
Implementation Method 1
a first laser configured to irradiate a first laser light having a first wavelength to the mask
Implementation Method 2
a second laser configured to irradiate a second laser light having a second wavelength different from the first wavelength to the mask
Data Source
AI summary
A micro light emitting diode (LED) transfer device includes a transfer part configured to transfer a relay substrate having at least one micro LED; a mask having openings corresponding to a position of the at least one micro LED; a first laser configured to irradiate a first laser light having a first wavelength to the mask; a second laser configured to irradiate a second laser light having a second wavelength different from the first wavelength to the mask; and a processor configured to: control the at least one micro LED to contact a coupling layer of a target substrate, and based on the coupling layer contacting the at least one micro LED, control the first laser to irradiate the first laser light toward the at least one micro LED, and subsequently control the second laser to irradiate the second laser light toward the at least one micro LED.