Micro LED Element Transfer Using a Flattened Cover Adhesive Layer

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Solution Overview

Problem

Existing methods for transferring thin micro LED elements face challenges such as damage from vacuum chucks and electrostatic chucks, and difficulties in achieving high yield due to inadequate adhesive forces between the carrier film and the target substrate.

Innovation Solution

An element transferring method involving a carrier film with a cover adhesive layer, where the second surface of the element is covered and the cover adhesive layer is pressed flat to match the terminal height, allowing stable transfer to a target substrate with improved adhesive forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If vacuum chuck is used to transfer large and thick elements, then transfer capability is improved, but thin elements (20 μm or less) are damaged due to pressure

Engineering Contradiction:

Improvetransfer capabilityVSAvoidelement damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental transfer mechanism from mechanical vacuum pressure to thermal expansion-driven transfer. By controlling the temperature of the carrier film, the element is transferred without experiencing damaging pressure forces, thus enabling transfer of thin elements (20 μm or less) while maintaining high transfer capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical vacuum chuck system with a thermal field-based transfer system. Instead of using mechanical pressure to adhere and transfer elements, the invention uses controlled thermal expansion of the carrier film to achieve transfer, eliminating the harmful mechanical pressure that damages thin elements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If electrostatic chuck technology is used for element transfer, then transfer capability is improved, but thin elements vulnerable to static electricity are damaged and large area transfer is difficult

Engineering Contradiction:

Improvetransfer capabilityVSAvoidstatic electricity damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electrostatic field-based transfer system with a thermal field-based system. By using controlled thermal expansion of the carrier film, the invention eliminates static electricity-related damage while achieving effective transfer capability, including large area transfer that was difficult with electrostatic chucks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If van der Waals adhesive force of polymer stamp is used for thin film element transfer, then transfer capability for thin elements is improved, but adhesive force management becomes difficult resulting in deteriorated transfer yield

Engineering Contradiction:

Improvetransfer capability for thin elementsVSAvoidtransfer yield

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the transfer mechanism from adhesive force-based to thermal expansion-based. By controlling the temperature of the carrier film, the element is transferred without relying on adhesive force management, thus achieving both high transfer capability for thin elements and high transfer yield without the reliability issues of adhesive force control.

Inventive Principle:

Principle #35Parameter changes

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 enhances the yield of element transfer by ensuring stable adhesion to the target substrate and preventing the element from being separated from the substrate during carrier film separation, thereby improving the overall manufacturing process efficiency.

Implementation Method 1

the carrier film is pressed so that the surface of the cover adhesive layer is flat at the same height as the terminal

Methodology Applied

Scientific EffectPressure: Pressure Increase

Implementation Method 2

the adhesive force between the carrier film and the element must be managed to be greater than the adhesive force between the source substrate and the element

Methodology Applied

Scientific EffectAdhesive force: Adhesive

Implementation Method 3

the cover adhesive layer may be formed into a second gel state having a second hardness degree greater than a first hardness degree by being pre-baked after a cover adhesive material of a first gel state having the first hardness degree is prepared

Methodology Applied

Scientific EffectPhase transition: Phase Change

Data Source

PatentUS12315742B2Element transferring method and electronic panel manufacturing method using the same

Publication Date: 2025.05.27 CENT FOR ADVANCED META MATERIALS

AI summary

An embodiment of the present invention provides an element transferring method that may increase a yield of transferring an element, and an electronic panel manufacturing method using the same. The element transferring method includes: preparing a carrier film in which a first surface of an element on which a terminal is formed is adhered to an adhesive surface; providing a cover adhesive layer on the adhesive surface so that the second surface of the element that is opposite to the first surface and where the terminal is not formed is covered; transferring the element to the target substrate by adhering the cover adhesive layer to the target substrate while the second surface is facing the target substrate; and separating the carrier film from the element, wherein in transferring the element, the carrier film is pressed so that the surface of the cover adhesive layer is flat at the same height as the terminal.