Micro-LED Pick-Up Head Alignment With Touchdown Force Feedback
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Solution Overview
Problem
Traditional display manufacturing techniques fail to accurately detect and compensate for spatial offsets between light emitters and electrical interconnects, leading to electrical failures in micro-LED displays used in VR, AR, and MR devices.
Innovation Solution
A display assembly system incorporating a fine positioning tool with a pick-up head and touchdown sensor that measures pressure and angular forces to ensure precise alignment and bonding of micro-LEDs to a backplane, utilizing a combination of piezoelectric sensing and laser interferometry for high accuracy, and a coarse positioning tool for broader movements, along with a 'Lights-On-Test' unit for verifying electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional display manufacturing techniques are used to place light-emitting structures on backplane, then the manufacturing process is simple, but spatial offsets between light emitters and electrical interconnects cannot be detected or compensated, resulting in electrical failures
Solution Approach 1:
The system performs preliminary detection of spatial offsets between light emitters and electrical interconnects using vision systems before the bonding process. This allows the system to pre-calculate and pre-position the pick-up head to compensate for detected misalignments, ensuring accurate electrical connections before actual bonding occurs.
Solution Approach 2:
The system implements real-time feedback loops where vision systems continuously monitor the positions of light-emitting structures and electrical interconnects. The detected spatial offset information is fed back to the fine positioning tool to dynamically adjust the placement position, ensuring accurate alignment despite manufacturing variations.
2Manufacturing precision
If fine positioning tool with multiple sensing systems is used to detect and compensate spatial offsets, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system merges multiple sensing technologies (piezoelectric sensors for force detection, laser interferometry for position measurement, and vision systems for spatial offset detection) into an integrated fine positioning tool. This consolidation allows simultaneous multi-parameter measurement and compensation without requiring separate complex systems for each function.
Solution Approach 2:
The fine positioning tool is designed as a multi-functional device that can perform detection, measurement, and compensation functions simultaneously. The pick-up head incorporates multiple sensors that work together to detect spatial offsets, measure positions, and adjust alignment in a single integrated operation, reducing the need for multiple separate devices.
3Manufacturing precision
If iterative adjustments are made during bonding process to maintain precision, then bonding accuracy is improved, but manufacturing time increases
Solution Approach 1:
The system performs preliminary detection and compensation of spatial offsets before the bonding process begins. By pre-positioning the light-emitting structures with accurate alignment based on vision system data, the need for iterative adjustments during bonding is minimized, allowing the bonding process to proceed efficiently with fewer cycles.
Solution Approach 2:
The system replaces iterative mechanical adjustment during bonding with a single-pass precise positioning approach. The fine positioning tool uses sensor feedback to achieve accurate alignment in one operation, eliminating the need for repeated mechanical adjustments and improving bonding throughput while maintaining precision.
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 system ensures accurate placement and bonding of micro-LEDs, reducing electrical failures by providing real-time feedback for iterative adjustments and maintaining precision during the bonding process, even at high temperatures, thus enhancing the reliability of micro-LED displays.
Implementation Method 1
a fine positioning tool 105...utilizing a combination of piezoelectric sensing and laser interferometry for high accuracy
Implementation Method 2
utilizing a combination of piezoelectric sensing and laser interferometry for high accuracy
Data Source
Figure 1
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Figure 3A~3B
AI summary
Embodiments herein address these and other issues by providing a display assembly system with a pick-up tool having 6 degrees of freedom (6DOF) coupled with a pick-up head having an at least partially transparent adhesive element to which light-emitting structures may be adhered for picking and placement during the display manufacture process. Embodiments further include a touchdown sensor coupled with the pick-up tool and pick-up head that allow sensing of a force applied to the pick-up head in an upward direction.