Laser-Patterned Connection Film Mask for Micro-LED Transfer
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Solution Overview
Problem
Existing methods for manufacturing mini-LED and micro-LED displays face challenges in achieving excellent light transmissive properties and productivity due to the application of connection films like ACF, which can obstruct light transmission and increase repair time when defects occur.
Innovation Solution
A method involving a mask with a light-shielding portion of a predetermined shape is used to form individualized pieces of curable resin film, allowing laser light to pass around the periphery, and a laser lift-off process is employed to create these pieces on a transparent substrate, followed by transfer and mounting on a wiring substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACF is entirely pasted to the element mounting surface of the substrate, then the connection between LEDs and substrate is ensured, but the adhesive resin and conductive particles remain between adjacent LEDs, blocking light transmission and reducing light transmissive properties
Solution Approach 1:
The connection film is divided into individualized pieces that are attached only at specific locations (directly below each LED), rather than covering the entire substrate surface. This segmentation allows light to pass through the spaces between individualized pieces while maintaining reliable electrical connection at each LED location.
Solution Approach 2:
The adhesive resin and conductive particles are localized only at the positions where LEDs are mounted (directly below each LED), rather than being distributed across the entire substrate. This local concentration ensures reliable connection where needed while leaving other areas transparent for light transmission.
2Illumination intensity
If ACF is attached only directly below the LEDs, then light transmissive properties are obtained, but it is difficult to attach connection films precisely at these locations, deteriorating transferability and increasing tact time
Solution Approach 1:
Individualized pieces of the connection film are prepared in advance on a temporary carrier substrate in precise arrays before transfer. This preliminary arrangement ensures that during the transfer process, each individualized piece is already positioned correctly for attachment below its corresponding LED, improving both precision and efficiency.
Solution Approach 2:
A carrier substrate is used as an intermediary to hold and organize individualized pieces of the connection film in precise arrays before transfer to the final substrate. This intermediary structure enables easy handling and precise positioning during the transfer process, improving both transferability and placement accuracy.
3Ease of operation
If the individualized pieces have poor shape, then the transferability to substrate or LED deteriorates, but achieving excellent shape requires complex mask design and manufacturing
Solution Approach 1:
The individualized pieces are designed with rounded corners or curved shapes rather than sharp angles. This curvature prevents stress concentration at corners during handling and transfer, improving transferability and reducing the likelihood of damage or deformation during the manufacturing process.
Solution Approach 2:
The individualized pieces are designed with asymmetric shapes that optimize both handling characteristics and functional performance. The asymmetric design allows for easy identification of orientation during transfer while maintaining excellent adhesion properties, simplifying the overall manufacturing process despite the complex requirements.
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 enhances the workability and transferability of individualized pieces, improving tact time and reducing defects in the manufacturing process of display devices.
Implementation Method 1
irradiating a curable resin film formed on a base material with laser light from the base material side to remove the curable resin film in the irradiated area
Implementation Method 2
A mask having a light-shielding portion of a predetermined shape that blocks laser light within an opening that allows laser light to pass through
Data Source
AI summary
A mask and a method for manufacturing the mask with excellent processability and transferability of individualized pieces, as well as a method for manufacturing a display device and a display device. By using a mask having a predetermined shape of a light-shielding portion that blocks laser light within an opening that transmits laser light, laser light is irradiated from the base material side to the curable resin film formed on the base material to remove the curable resin film in the irradiated portion, thereby forming individualized pieces of a predetermined shape composed of a curable resin film with a reaction rate of 25% or less on the base material. This allows for excellent workability and transferability of the individualized pieces, thereby improving tact time.