Fluidic MicroLED Mass Transfer With Trap-Site Keel Alignment
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Solution Overview
Problem
The current microLED display assembly processes, such as pick-and-place and mass transfer, are inefficient and costly due to their serial nature, high defect rates, and limitations in achieving arbitrary display resolutions, leading to high production costs and low yields.
Innovation Solution
The use of fluidic assembly techniques to prepare and transfer microLEDs onto a carrier substrate, allowing for flexible pitch expansion and improved assembly methods that enable the use of a simple, reusable transfer stamp with a non-conductive keel or bio-molecule securing mechanism, facilitating the bonding of microLEDs to a display substrate with high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pick-and-place method is used to assemble microLEDs, then each microLED can be individually positioned, but the assembly process becomes painfully slow and productivity is low
Solution Approach 1:
The patent merges multiple individual microLED assembly operations into a single parallel mass transfer operation. By using a stamp with multiple trap sites that can simultaneously pick up and place numerous microLEDs, the system combines serial precision positioning with parallel execution, thereby maintaining positioning accuracy while dramatically increasing assembly throughput.
Solution Approach 2:
The patent implements preliminary action by pre-arranging microLEDs in a carrier array before transfer. The microLEDs are organized in a predetermined pattern on the carrier substrate, allowing the stamp to pick them up en masse in the correct configuration. This pre-organization eliminates the need for individual positioning during the assembly process, maintaining precision while enabling parallel operation.
2Productivity
If conventional mass transfer method is used, then assembly speed increases, but defect rates increase and manufacturing precision decreases
Solution Approach 1:
The patent introduces an intermediary carrier substrate that serves as a buffer between the microLED source and the final display substrate. The carrier holds microLEDs in precise positions with high-density arrays, acting as a mediator that enables accurate transfer. This intermediary structure allows the stamp to transfer microLEDs in parallel while maintaining positioning accuracy through the pre-configured carrier array.
Solution Approach 2:
The patent replaces traditional mechanical pick-and-place mechanisms with a fluidic or adhesive-based mass transfer system. Instead of individually manipulating each microLED with mechanical grippers, the system uses a stamp with trap sites that can simultaneously capture and release multiple microLEDs through controlled adhesive forces or fluidic pressure, thereby achieving both high speed and high precision.
3Ease of manufacture
If microLEDs are assembled in fixed pitch patterns, then manufacturing is simplified, but adaptability to different display resolutions is limited
Solution Approach 1:
The patent implements dynamics by making the pitch configuration adjustable rather than fixed. The carrier substrate and stamp are designed to accommodate variable pitch patterns, allowing the system to dynamically reconfigure the microLED array layout according to different display resolution requirements. This enables the same manufacturing system to produce multiple display types without retooling, achieving both simplicity and versatility.
Solution Approach 2:
The patent creates a universal assembly system that can handle multiple display resolutions and configurations through a single carrier-substrate-stamp platform. The carrier is designed with adaptable pitch patterns that can be reconfigured for different pixel densities, making the manufacturing system multi-functional. This universal approach eliminates the need for dedicated tooling for each resolution, simplifying manufacturing while maximizing adaptability.
4Manufacturing precision
If high density microLED arrays are assembled, then display resolution improves, but the complexity of assembly processes increases
Solution Approach 1:
The patent applies segmentation by dividing the high-density microLED array assembly into modular components: a carrier substrate that holds the microLEDs in a high-density pattern, a stamp with corresponding trap sites, and a transfer mechanism. This segmentation allows the complex task of assembling high-density arrays to be broken down into manageable, repeatable operations, reducing overall process complexity while achieving high resolution.
Data Source
AI summary
A microLED mass transfer stamping system includes a stamp substrate with an array of trap sites, each configured with a columnar-shaped recess to temporarily secure a keel extended from a bottom surface of a microLED. In the case of surface mount microLEDs, the keel is electrically nonconductive. In the case of vertical microLEDs, the keel is an electrically conductive second electrode. The stamping system also includes a fluidic assembly carrier substrate with an array of wells having a pitch separating adjacent wells that matches the pitch separating the stamp substrate trap sites. A display substrate includes an array of microLED pads with the same pitch as the trap sites. The stamp substrate top surface is pressed against the display substrate, with each trap site interfacing a corresponding microLED site, and the microLEDs are transferred. Fluidic assembly stamp substrates are also presented for use with microLEDs having keels or axial leads.