Micro Device Transfer via Roll-to-Roll Adhesive Strength Control
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Solution Overview
Problem
Current methods for transferring micro-LEDs to substrates are inefficient, particularly for large displays, as they require individual handling and struggle with low adhesive strength in roll transfer processes, making it difficult to handle a large number of micro-devices simultaneously.
Innovation Solution
A micro-device transfer method that regulates adhesive strength by controlling the press-fitting depth of micro-devices on a carrier film, generating two types of adhesive strength: first through compression and second through mechanical deformation, allowing for sequential release and transfer without additional strengthening processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a vacuum chuck is used to transfer micro-LEDs one by one, then individual device transfer is achieved, but the manufacturing time becomes very long and handling becomes difficult
Solution Approach 1:
The patent merges multiple micro-LED transfer operations into a single roll-to-roll process, where a continuous carrier film transfers multiple micro-LEDs simultaneously to the substrate, eliminating the need for individual vacuum chuck operations and dramatically increasing productivity
Solution Approach 2:
The patent replaces the vacuum chuck mechanical system with a roll-to-roll transfer mechanism using a flexible carrier film, enabling continuous batch transfer of micro-LEDs instead of sequential individual transfer
2Productivity
If typical solder pastes are used in roll transfer process, then continuous transfer is enabled, but adhesive strength becomes very low
Solution Approach 1:
The patent changes the composition parameters of the solder paste by adding specific adhesive agents and flux components, transforming it from a typical low-adhesion solder paste to a high-adhesion paste suitable for roll-to-roll transfer of micro-LEDs
Solution Approach 2:
The patent creates a composite solder paste material combining solder particles, adhesive agents, and flux components, achieving both continuous transfer capability and high adhesive strength simultaneously
3Strength
If additional processes are added to enhance adhesive strength, then bond strength is improved, but process complexity increases
Solution Approach 1:
The patent enables the solder paste to self-generate sufficient adhesive strength through its enhanced composition during the roll-to-roll transfer process itself, eliminating the need for separate adhesive enhancement processes or additional process steps
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
Enables continuous transfer of multiple micro-devices to a substrate using mechanical deformation-based adhesive strength, improving efficiency and handling capabilities compared to traditional chemical-based methods.
Implementation Method 1
a second adhesive generation step in which the micro-device is bonded to the adhesive layer through press-fitting in the compression step to generate second adhesive strength between the micro-device and the adhesive layer
Implementation Method 2
the viscoelastic coefficient of the adhesive layer may be regulated such that the second adhesive strength proportional to the press-fitting depth of the micro-device press-fitted into the adhesive layer becomes less than the first adhesive strength
Data Source
AI summary
A method for transferring a micro device, includes: a compression step in which a carrier film having a micro-device attached to an adhesive layer thereof is brought into contact with a substrate comprising a solder deposited on metal electrodes formed on the substrate and is compressed on the substrate; a first adhesive strength generation step in which the solder disposed between the micro-device and the metal electrodes is compressed in the compression step to generate first adhesive strength between the micro-device and the solder; a second adhesive generation step in which the micro-device is bonded to the adhesive layer through press-fitting in the compression step to generate second adhesive strength between the micro-device and the adhesive layer; and a release step in which the carrier film is separated from the substrate, with the micro-device adhered to the solder.