LED Transfer via Laser-Weakened Adhesive and Ciliary Units
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Solution Overview
Problem
Conventional LED transfer methods face challenges such as uniformity issues during bonding interface changes, physical damage to thin LED structures, and difficulties in separating LEDs from support substrates, leading to reduced reliability and efficiency in transferring micro LED structures.
Innovation Solution
The method involves bonding p-n junction LED structures to a temporary substrate using metal bonding layers, which are then separated when the adhesive strength is weakened by light of a specific wavelength, allowing for easy transfer and maintaining adhesive strength through ciliary units with van der Waals or capillary attractive forces, enabling selective transfer of quality LED structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED structures are transferred using conventional methods, then transfer process can be completed, but uniformity issues occur during bonding interface changes and physical damage happens to thin LED structures
Solution Approach 1:
A temporary substrate is introduced as an intermediary carrier to bond LED structures during transfer. The temporary substrate provides a stable bonding interface that prevents direct contact between the LED structures and the final substrate, eliminating uniformity issues and physical damage during the transfer process. The temporary substrate can be easily separated from the LED structures after transfer using laser irradiation.
Solution Approach 2:
The conventional mechanical bonding and separation process is replaced by optical field irradiation (laser) to weaken adhesive strength and separate LED structures from the temporary substrate. This substitution of mechanical action with optical energy enables precise, contactless separation that avoids physical damage to thin LED structures while maintaining high transfer uniformity.
2Productivity
If LED structures are transferred using conventional methods, then transfer can be performed, but physical damage occurs to thin LED structures
Solution Approach 1:
Mechanical separation forces are replaced by optical field irradiation (laser) that selectively weakens the adhesive bonding between LED structures and the temporary substrate. This non-contact optical method enables high-speed transfer while completely avoiding mechanical stress and physical damage to the thin LED structures, maintaining both productivity and structural integrity.
Solution Approach 2:
The adhesive strength between LED structures and the temporary substrate is dynamically controlled by changing the energy state through laser irradiation. The laser energy changes the bonding parameters locally, allowing the adhesive strength to be weakened on demand for separation while maintaining strong bonding during the transfer process, thus preserving LED structure integrity throughout.
3Ease of operation
If LED structures are transferred using conventional methods, then transfer process can be completed, but difficulties occur in separating LEDs from support substrates
Solution Approach 1:
Difficult mechanical separation processes are replaced by optical field irradiation that selectively weakens adhesive strength. The laser irradiation method provides precise, controllable separation by delivering energy only to the adhesive layer between LED structures and the temporary substrate, making separation easy to perform while maintaining high transfer reliability through consistent, uniform energy distribution.
Solution Approach 2:
The adhesive bonding state is transitioned from a strong bonded phase to a weakened separation phase through laser irradiation. The optical energy induces a phase change or state transition in the adhesive material, enabling easy separation of LED structures from the temporary substrate while maintaining reliable transfer through controlled energy input that prevents damage during the transition.
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 reliable and efficient transfer of LED structures onto another substrate, maintaining adhesive strength during repetitive processes and enabling selective removal of faulty structures, thereby improving the reliability and flexibility of LED applications.
Implementation Method 1
causing a phase change of an adhesive layer for at least one of the micro LED structures
Implementation Method 2
inducing a phase change of an interface from solid to liquid by heating the interface
Implementation Method 3
maintain adhesive strength with the LED structures by having van der Waals attractive force or capillary attractive force with surfaces of the LED structures
Implementation Method 4
maintain adhesive strength with the LED structures by having van der Waals attractive force or capillary attractive force with surfaces of the LED structures
Data Source
AI summary
The present invention is intended to provide a light-emitting diode (LED) structure which can be easily transferred onto another substrate, a transfer assembly whose adhesive strength with LED structures can be maintained in spite of repetitive transfer processes, LED structures and a transfer assembly for selectively transferring the LED structures, and a transfer method using the same.