Laser Lift Transfer of μ-LED Components With Controlled Adhesion
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Solution Overview
Problem
The transfer of small optoelectronic components, such as μ-LEDs, is challenging due to difficulties in controlling adhesive forces, leading to incomplete or faulty transfers, where components may adhere to stamp pads or not be placed correctly.
Innovation Solution
A method using a light-conducting lifting element with a light emitting surface that creates a strong connection with the component by local melting of a transfer material with laser pulses, allowing for precise separation and repositioning of the component, ensuring accurate transfer to a target area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional stamp pad is used to transfer small optoelectronic components, then the transfer process can be performed, but the adhesive forces cannot be controlled, leading to incomplete or faulty transfers
Solution Approach 1:
The patent replaces the conventional mechanical stamp pad system with a laser-based system. A laser beam is focused onto the transfer material to locally melt it, creating a controlled adhesive bond between the lifting element and the component. This substitution of mechanical adhesive control with optical/thermal control enables precise manipulation of small components without the variability of conventional stamp pads.
Solution Approach 2:
The patent changes the physical state of the transfer material by controlling its temperature through laser heating. The transfer material is selectively melted (phase change from solid to liquid) to create adhesive bonds, then allowed to solidify to maintain the bond. This dynamic parameter change (temperature control) enables reliable transfer of small components with precise positioning.
2Productivity
If the adhesive force between stamp and component is increased to ensure complete transfer, then more components can be transferred, but the components may not be placed correctly or may be damaged
Solution Approach 1:
The patent applies adhesive force locally rather than uniformly across the entire component surface. The laser beam is focused to a specific spot on the transfer material, melting only the localized area needed for bonding. This local quality approach allows the lifting element to grip the component securely while maintaining precise placement control, as the adhesive bond is created only where needed.
Solution Approach 2:
The patent uses periodic laser pulsing to control the adhesive process. The laser is activated in controlled pulses to melt the transfer material, then deactivated to allow solidification. This periodic action enables precise control over when adhesive bonds are formed and released, ensuring both complete transfer and accurate placement without component damage.
3Reliability
If a light-conducting lifting element with laser melting is used, then precise and reliable transfer is achieved, but the device complexity increases
Solution Approach 1:
The light-conducting lifting element serves multiple functions: it provides mechanical support for lifting the component, conducts the laser beam to the transfer material, and acts as the deposition tool. This multi-functionality reduces the need for separate systems for heating, positioning, and transferring, thereby managing device complexity while achieving reliable transfer.
Solution Approach 2:
The transfer material acts as an intermediary between the lifting element and the component. It is deposited on the lifting element, melted by the laser to create a controlled adhesive bond, and then solidifies to maintain the connection during transfer. This intermediary material simplifies the interaction between the lifting element and component, enabling reliable transfer without complex mechanical coupling mechanisms.
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 method enables secure, error-free transfer of small optoelectronic components by creating a strong and controlled connection with the lifting element, allowing for selective placement and reducing residue on the transfer area, suitable for manufacturing displays and other applications.
Implementation Method 1
A first laser light pulse is generated, which passes through the light emitting surface. The laser light pulse has an energy input that causes a local melting of a transfer material
Implementation Method 2
The laser light pulse has an energy input that causes a local melting of a transfer material, which is arranged between the light emitting surface and the transfer area
Implementation Method 3
a light-conducting lifting element is provided, which has a light emitting surface. This is positioned opposite the transfer area of the at least one component. A first laser light pulse is then generated, which passes through the light emitting surface
Data Source
AI summary
In an embodiment a method includes providing at least one component attached to a first carrier via a support holder, positioning a light-conducting lifting element with a light emitting surface opposite the transfer area, generating a first laser light pulse through the light emitting surface, locally melting a transfer material between the light emitting surface and the transfer area caused by the first laser light pulse, connecting the light emitting surface to the transfer area with the melted transfer material, lifting the at least one component so as to separate the component from the support holder, positioning the at least one component above a deposition area, generating a second laser light pulse through the light emitting surface so that the transfer material is melted again and moving the lifting element away from the transfer area before the transfer material solidifies and so that the component remains on the deposition area.