LED Testing Circuit Layout for Small-Electrode Wafer Inspection
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Solution Overview
Problem
Conventional LED testing methods struggle with small-sized LEDs due to the tiny size of their electrodes and the space between them, making it difficult to apply probes effectively.
Innovation Solution
A manufacturing method that involves dividing a substrate into zones, arranging LEDs in groups within these zones, and using a testing circuit to electrically connect and test the LEDs in each group, allowing for the acquisition of photoelectric characteristics and presentation in an image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional probes are used to test small-sized LEDs, then the testing method is simple and direct, but the probes cannot effectively contact the tiny electrodes due to the small size of the LEDs
Solution Approach 1:
The substrate is divided into multiple zones, with each zone containing a group of LEDs. This segmentation allows the testing circuit to handle multiple LEDs simultaneously rather than testing each LED individually with probes, thereby overcoming the difficulty of probe application to tiny electrodes while maintaining measurement precision.
Solution Approach 2:
A testing circuit is introduced as an intermediary between the test system and the LED electrodes. The testing circuit includes signal lines that extend from the edge of the substrate to the LED electrodes, allowing electrical connection without requiring direct probe contact with the tiny electrodes. This intermediary structure enables accurate measurement while avoiding the operational difficulty of probe application.
2Productivity
If individual LED testing is performed, then each LED can be tested separately, but the testing process becomes time-consuming and inefficient
Solution Approach 1:
Multiple LEDs within the same zone are electrically connected in parallel through the testing circuit, allowing them to be tested simultaneously as a group. This merging approach enables the testing system to process multiple LEDs in one operation, dramatically improving productivity and reducing the total testing time compared to individual LED testing.
Solution Approach 2:
The testing circuit is designed to test all LEDs in a zone simultaneously, even though individual LED testing would be sufficient. This partial action (testing groups rather than individuals) exceeds the minimum requirement and achieves significant time savings with acceptable measurement accuracy.
3Productivity
If the substrate is divided into zones with LED groups, then testing efficiency is improved, but the device complexity increases due to the testing circuit structure
Solution Approach 1:
The testing circuit is designed with universal signal lines that can serve multiple functions: providing electrical connection for testing, extending from the substrate edge to the LEDs, and enabling simultaneous testing of multiple LEDs. This multi-functionality reduces the need for separate specialized components, thereby limiting the increase in device complexity while maintaining high productivity.
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 method enables efficient testing of small-sized LEDs by overcoming the challenges of their miniature size, allowing for accurate photoelectric characteristic measurement and identification of defective LEDs.
Implementation Method 1
In a conventional LED testing method such as electroluminescence (EL) testing, probes are applied to the electrodes of the LED to input a testing current to obtain the photoelectric characteristics of the LED
Data Source
AI summary
A manufacturing method for a LED is disclosed. The method includes: providing a substrate with an upper surface; preparing a plurality of LEDs on the upper surface; wherein the upper surface is divided into a plurality of zones, the plurality of LEDs composes a plurality of LED groups, and each of the LED group is disposed in one of the plurality of zones; preparing a testing circuit to electrically connecting the plurality of LEDs in one of the plurality of LED groups; testing the plurality of LEDs in the one of the plurality of LED groups by the testing circuit to obtain photoelectrical characteristics of the plurality of LEDs in the one of the plurality of LED groups; and presenting the photoelectric characteristics in an image.