LED Mass-Transfer Apparatus Using KGD Data for Selective Release
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Solution Overview
Problem
Current micro-LED manufacturing methods, such as pick and place, face limitations in throughput, accuracy, and yield due to their reliance on physical stamping, which is 'blind' to the functionality of LED devices, leading to high error rates and the need for costly post-transfer repair in mass-producing displays like 4K UHD TVs.
Innovation Solution
The development of a mass-transfer apparatus and method using KGD data to selectively transfer only functional LED devices, employing an energy beam like a laser to release LEDs based on die/location matching criteria, allowing for high-speed and accurate placement with the option to fill missing locations, thereby improving throughput and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical pick and place methods are used to transfer LED devices, then manufacturing throughput can be increased, but transfer accuracy and yield deteriorate due to blind transfer without functionality verification
Solution Approach 1:
The patent performs LED device functionality testing and generates KGD data files before the mass-transfer process. This preliminary action identifies functional devices and creates a mapping between source substrate locations and target substrate locations, ensuring that only known good devices are transferred to the correct positions, thereby resolving the contradiction between high throughput and transfer accuracy.
2Productivity
If physical stamp pick and place methods are used, then mass production capability is improved, but error rates increase due to inability to verify LED functionality during transfer
Solution Approach 1:
The patent implements a feedback mechanism where KGD test data from previously tested LED devices is used to control the mass-transfer process. The system reads the KGD data file, determines which devices are functional, and uses this information to guide the transfer process, ensuring that only functional devices are placed on the target substrate. This feedback loop eliminates blind transfer and significantly improves transfer yield while maintaining mass production capability.
3Speed
If blind mass transfer of LED devices is performed, then manufacturing speed is increased, but post-transfer repair requirements and costs increase
Solution Approach 1:
The patent performs the functionality verification and location mapping actions before the mass-transfer process begins. By generating KGD data files that identify functional devices and their correct target positions in advance, the system ensures that the high-speed transfer process places only good devices in the correct locations, eliminating the need for post-transfer repair operations and reducing associated costs.
4Manufacturing precision
If selective transfer of KGD devices is implemented, then transfer precision is improved, but device complexity of the transfer apparatus increases
Solution Approach 1:
The patent replaces complex mechanical selection mechanisms with a data-driven approach. Instead of using mechanical sensors or actuators to identify and select individual functional LED devices during transfer, the system uses pre-acquired KGD electrical test data stored in files to control the transfer process. This substitution of mechanical selection with information-based control achieves high transfer precision while avoiding the complexity of real-time device-by-device mechanical identification systems.
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 enables the high-volume, error-free assembly of micro-LED displays by ensuring only functional LEDs are transferred, significantly increasing manufacturing line efficiency and reducing the need for post-transfer repairs, capable of populating over 100-250 million LEDs per hour.
Implementation Method 1
A beam induced release method is utilized to release selected LED devices from a source substrate with a source areal density to a target substrate with a often different target areal density
Data Source
AI summary
Embodiments relate to mass-transfer methods useful for fabricating products containing Light Emitting Diode (LED) structures. LED arrays are transferred from a source substrate to a target substrate by an in-process functional test Known-Good Die (KGD) driven mass-transfer of a plurality of LED devices in a high-speed flexible manner. Certain preferred embodiments using beam-addressed release (BAR) mass-transfer approaches are able to utilize a Known Good Die (KGD) data file of the source substrate in a manner that avoids additional steps, rework and yield losses.