Micro-LED Flip-Chip Electrode Structure for Connection Inspection
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Solution Overview
Problem
In micro-LED display manufacturing, ensuring a secure electrical connection between micro-LED electrodes and substrate electrodes is challenging, particularly in flip-chip mounting methods, where direct contact and heating are used, and effective inspection methods for connection quality are lacking.
Innovation Solution
The use of n-side and p-side pad electrodes with protruding portions that contact the substrate electrodes, allowing for indentation observation to assess electrical connection quality, combined with a method of pressing and crimping these electrodes to secure the connection and inspecting the resulting indentations for adequate contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flip-chip mounting method with direct contact and heating is used, then electrical connection between micro-LED electrodes and substrate electrodes is achieved, but it is difficult to confirm whether the connection is sufficiently secured
Solution Approach 1:
The patent uses optical microscopy to detect indentation marks formed on the substrate electrode surface by the protruding portions of the pad electrodes during crimping. The visual appearance change (indentation formation) provides direct evidence of sufficient electrical connection without requiring complex electrical testing, thus resolving the inspection difficulty while maintaining connection reliability
Solution Approach 2:
The patent replaces complex electrical connection verification systems with a simple mechanical indentation observation method. By designing pad electrodes with protruding portions that create visible indentation marks on the substrate electrode during crimping, the system substitutes sophisticated electrical measurement equipment with basic optical inspection, achieving both reliable connection and easy detection
2Difficulty of detecting and measuring
If protruding portions are added to pad electrodes to enable indentation observation, then connection quality can be visually inspected, but electrode structure becomes more complex
Solution Approach 1:
The pad electrode is segmented into two functional parts: a flat base portion for electrical contact and a protruding portion for creating the indentation mark. This segmentation allows the electrode to perform dual functions - electrical connection and quality indication - without requiring entirely new components, thus adding inspection capability while minimizing structural complexity
Solution Approach 2:
The protruding portion of the pad electrode serves multiple functions: it ensures proper alignment during mounting, creates the indentation mark for quality inspection, and maintains electrical contact during crimping. This multi-functionality approach adds inspection capability without requiring separate alignment features or marking mechanisms, thereby limiting the increase in device complexity
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 ensures reliable electrical connections between micro-LED chips and substrate electrodes, facilitating effective quality evaluation through visible indentation inspection, thereby enhancing the manufacturing process and display device performance.
Implementation Method 1
fixed by heating and crimping in the presence of a resin such as NCF (Non Conductive Film)
Data Source
AI summary
A display device includes a substrate, a first electrode and a second electrode on the substrate, and an LED chip disposed on the first electrode and the second electrode and having an n-side pad electrode and a p-side pad electrode. The n-side pad electrode has a first protruding portion, the first protruding portion protruding toward the substrate and in contact with the first electrode, and the p-side pad electrode has a second protruding portion, the second protruding portion protruding toward the substrate and in contact with the second electrode.