Growth-Substrate Micro-LED Testing Before Display Bonding
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Solution Overview
Problem
Existing display devices using micro LEDs face challenges in identifying defective light emitting elements before they are separated from the growth substrate and bonded, which can lead to reduced display quality due to undetected defects.
Innovation Solution
A lighting test method and system that includes forming an electric field between a probe card and a conductive plate on the growth substrate, using a probe card with protruding pins to contact electrode portions of light emitting elements, and an optical test unit to image and identify defective elements, allowing for their removal before transport and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light emitting elements are simultaneously formed on a growth substrate, then productivity is improved, but the probability of defects increases
Solution Approach 1:
The patent applies preliminary action by performing a lighting test on the light emitting elements while they are still on the growth substrate, before separation and bonding processes. This allows defective elements to be identified and removed early in the manufacturing process, preventing them from compromising final display quality while maintaining the efficiency benefits of batch processing
2Ease of manufacture
If lighting test is performed after separation and bonding, then manufacturing process is simpler, but defective elements cannot be removed before integration
Solution Approach 1:
The patent performs the lighting test preliminarily while light emitting elements are still on the growth substrate, before separation and bonding operations. This early detection allows defective elements to be removed before integration into the final display device, ensuring high manufacturing precision without significantly complicating the overall process
Solution Approach 2:
The patent introduces a growth substrate as an intermediary platform that enables simultaneous formation and testing of multiple light emitting elements. The substrate serves as a temporary holding structure that allows batch processing and testing before individual elements are separated and bonded to their final positions
3Productivity
If defective elements are not removed before bonding, then production speed is maintained, but display quality deteriorates
Solution Approach 1:
The patent implements preliminary action by conducting lighting tests on the growth substrate before the separation and bonding processes. This allows defective light emitting elements to be identified and removed early, ensuring that only functional elements proceed to bonding, thereby maintaining both production efficiency and display quality
Solution Approach 2:
The patent employs feedback by using the lighting test to detect and identify defective light emitting elements. The test provides real-time information about element functionality, allowing the system to feedback and remove defective elements before they are bonded, thus maintaining high display quality without significantly reducing production speed
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
Enables the detection and removal of defective light emitting elements on the growth substrate, ensuring higher display quality by eliminating non-functional elements before integration into the display device.
Implementation Method 1
forming an electric field between a probe card electrically contacting the electrode portion on the plurality of light emitting elements, and a conductive plate facing the second semiconductor layer below the growth substrate
Implementation Method 2
obtaining an image by imaging the plurality of light emitting elements with an optical test unit; and checking whether light is emitted in areas corresponding to the plurality of light emitting elements, in the image
Data Source
AI summary
An embodiment provides a lighting test method of light emitting elements that include a second semiconductor layer, an active layer, a first semiconductor layer, and an electrode portion sequentially stacked each other on a growth substrate and spaced apart from each other. The lighting test method includes forming an electric field between a probe card electrically contacting the electrode portion on the light emitting elements, and a conductive plate facing the second semiconductor layer below the growth substrate; and testing whether the light emitting elements are lighted.