LED Pixel Mounting Pad Stack for Laser Chip Repair
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Solution Overview
Problem
The challenge in LED display devices is the low yield rate due to connection failures between LED chips and the circuit substrate, leading to pixel defects.
Innovation Solution
A display device design with a first and second mounting pad configuration, where the second pad serves as a spare, and a laser-based repair method to replace defective LED chips by removing the first pad and insulating layer, allowing a new chip to be mounted on the second pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If a spare mounting pad is added for repair purposes, then defective chips can be replaced, but the device structure becomes more complex
Solution Approach 1:
The patent resolves the complexity issue by utilizing the vertical dimension (z-axis) rather than adding horizontal space. The second mounting pad is positioned to overlap with the first mounting pad in plan view, effectively using the third dimension to accommodate the spare pad. This vertical stacking approach allows repair functionality without increasing the lateral footprint or apparent structural complexity from a top-down perspective.
Solution Approach 2:
The second mounting pad serves multiple functions: it acts as a spare for replacing defective LED chips, maintains electrical connection continuity, and preserves the original pixel structure. The overlapping configuration allows the same spatial region to serve both as the primary mounting location and as a backup, maximizing the utility of the existing structure.
2Difficulty of detecting and measuring
If laser processing is used to remove defective components, then precise repair is enabled, but additional processing steps increase manufacturing complexity
Solution Approach 1:
The patent replaces mechanical removal methods (such as physical cutting or chemical etching) with laser processing. The laser provides non-contact, precise removal of the LED chip, mounting pad, and insulating layer without requiring mechanical tooling or complex chemical processes. This substitution simplifies the repair equipment requirements while maintaining high precision in component removal.
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 enhances the yield rate by enabling efficient replacement of defective LED chips, maintaining high-definition display capabilities without additional space requirements.
Implementation Method 1
irradiating a first laser light to a first LED chip determined to be defective in a pixel and removing the first LED chip, irradiating a second laser light to a first mounting pad connected to the first LED chip in the pixel and removing the first mounting pad, irradiating a third laser light to an insulating layer overlapping the first mounting pad and removing the insulating layer
Data Source
AI summary
A display device includes a first LED chip arranged in a pixel, a first mounting pad arranged in the pixel and connected to the first LED chip, a second mounting pad arranged in the pixel, overlapping the first mounting pad in a plan view and electrically connected to the second mounting pad, and an insulating layer between the first mounting pad and the second mounting pad.