Laser-Patterned Anisotropic Conductive Film for Micro-LED Transfer
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Solution Overview
Problem
Existing methods for manufacturing mini-LED and micro-LED displays using anisotropic conductive films (ACF) face challenges in achieving excellent light transmissive properties and productivity due to adhesive resin and conductive particles obstructing light transmission and poor transferability of individualized pieces, leading to increased repair times.
Innovation Solution
A method involving laser irradiation of anisotropic conductive films on a base material to form individualized pieces with specific thickness and viscosity ranges, allowing precise placement and attachment of light-emitting elements, thereby improving workability and tact time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACF is entirely pasted to the element mounting surface, then connection reliability is improved, but light transmissive properties deteriorate due to adhesive resin and conductive particles blocking light
Solution Approach 1:
The ACF is divided into individualized pieces that are selectively placed only at the mounting positions of light-emitting elements, rather than being applied as a continuous film across the entire substrate. This segmentation allows light to pass through areas without ACF while maintaining reliable electrical and mechanical connections at element locations.
Solution Approach 2:
The ACF is applied locally only where needed - directly below light-emitting elements - rather than uniformly across the entire mounting surface. This localized application ensures connection reliability at critical points while preserving light transmission in non-critical areas.
2Illumination intensity
If ACF is attached only directly below LEDs, then light transmissive properties are improved, but transferability of individualized pieces deteriorates due to poor shape
Solution Approach 1:
The thickness of the ACF is precisely controlled within the range of 0.9 to 8 times the particle diameter of conductive particles, and the melt viscosity is adjusted to 2,000-800,000 Pa·s at 30°C. These parameter optimizations ensure that individualized pieces maintain excellent transferability and workability during the mounting process while preserving light transmission properties.
3Illumination intensity
If ACF is attached only directly below LEDs, then light transmissive properties are improved, but productivity deteriorates due to increased repair man-hours
Solution Approach 1:
By segmenting the ACF into individualized pieces with optimized dimensions and properties, each piece can be precisely placed and reliably transferred to mounting positions. This reduces placement errors and facilitates easier repair or replacement of individual elements, thereby improving overall productivity despite the selective application approach.
4Illumination intensity
If thickness of ACF is reduced, then light transmissive properties are improved, but workability of individualized pieces deteriorates
Solution Approach 1:
The ACF thickness is optimized to a specific range (0.9-8 times the particle diameter) that balances light transmission with mechanical workability. This thickness ensures sufficient structural integrity for handling and transfer operations while remaining thin enough to allow adequate light passage through the connection film.
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 method enables excellent workability and productivity by ensuring light transmissive properties and efficient transfer of individualized pieces, reducing repair times and enhancing display manufacturing efficiency.
Implementation Method 1
irradiating a laser light from a base material side to an anisotropic conductive film formed on a base material to remove the anisotropic conductive film in the irradiated area
Data Source
AI summary
A method for manufacturing an individualized-piece-film that can obtain excellent workability of individualized pieces, an individualized-piece-film, and a display device. The method irradiates a laser light from a base material side to an anisotropic conductive film formed on a base material to remove the anisotropic conductive film in the irradiated area (removal portion), thereby forming individualized pieces of a predetermined shape. The thickness of the anisotropic conductive film is 1 μm or more and 10 μm or less, the melt viscosity of the anisotropic conductive film at 30° C. is 2,000 Pa*s or more and 800,000 Pa*s or less, and 90% or more of the conductive particles in the anisotropic conductive film are present at an average of the center positions of the conductive particles in the thickness direction of the anisotropic conductive film.