Micro LED Photoluminescence Inspection With Dual-Wavelength Filtering
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Solution Overview
Problem
Existing inspection methods for micro LEDs, such as electroluminescence (EL), face challenges in efficiently detecting multiple LEDs due to reduced spacing between pads, leading to decreased detection efficiency and increased time and cost, as probe cards struggle to handle miniaturized LEDs.
Innovation Solution
An inspection device utilizing photoluminescence (PL) with a conversion device and filters to acquire images of multiple wavelengths, employing a secondary filter to remove short- and long-wavelength ranges, and a processing module to assess defects, using a beam splitter and multiple sensing elements to enhance detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probe card method is used for EL measurement, then electrical signals can be provided to LEDs to stimulate light emission, but detection efficiency decreases and inspection time increases when LED size is miniaturized
Solution Approach 1:
The patent replaces the mechanical probe card system with an optical inspection system using photoluminescence imaging. Instead of using physical probes to stimulate and detect light from individual LEDs, the system uses optical beams to illuminate multiple LEDs simultaneously and captures their photoluminescence signals using sensors, thereby eliminating the mechanical limitations of probe cards when dealing with miniaturized LEDs.
Solution Approach 2:
The patent transitions from one-dimensional sequential probing (one LED at a time using probe cards) to two-dimensional parallel imaging (multiple LEDs simultaneously using optical beams). By using optical imaging technology, the system can capture photoluminescence signals from multiple LEDs across a panel at the same time, dramatically improving detection efficiency.
2Quantity of substance
If probe spacing is reduced to detect more micro LEDs, then detection coverage increases, but structural limitations prevent further reduction in probe spacing
Solution Approach 1:
The patent replaces the mechanical probe card structure with an optical imaging system. Instead of relying on physical probes that have structural limitations on spacing, the system uses optical beams that can be focused and positioned with much finer precision, allowing detection of multiple micro LEDs without increasing device complexity.
Solution Approach 2:
The patent changes the fundamental parameter of detection from mechanical contact (probe spacing) to optical non-contact measurement (beam spacing). This parameter change allows the system to detect multiple LEDs at positions that would be impossible for mechanical probes, as optical beams can be positioned and focused with much greater precision and flexibility.
3Ease of operation
If EL measurement method is used, then electrical signals can stimulate light emission, but non-contact inspection capability is lost
Solution Approach 1:
The patent replaces the electrical contact-based EL measurement method with an optical non-contact inspection method. Instead of using probe cards to provide electrical signals and detect light, the system uses optical beams to illuminate the LEDs and optical sensors to capture their photoluminescence signals, enabling non-contact inspection while maintaining or improving detection capability.
Solution Approach 2:
The patent introduces optical beams and optical sensors as intermediaries between the inspection system and the LEDs. Instead of direct electrical contact, the system uses optical energy to stimulate the LEDs to emit photoluminescence signals, which are then captured by optical sensors. This intermediary approach enables non-contact inspection while maintaining detection capability.
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
The device enables non-contact inspection of micro LED panels, improving detection efficiency and reducing inspection time and costs by capturing detailed photoluminescence images with enhanced clarity and sensitivity.
Implementation Method 1
The light source emits a plurality of light beams to form a mixed light beam... to enable photoluminescence of the object and generating an inspection light beam
Implementation Method 2
The shortwave filter filters out the shortwaves of the first split light beam... The longwave filter filters out the longwaves of the second split light beam
Data Source
AI summary
The present invention provides an inspection device. A light source emits a mixed light beam to an object to enable photoluminescence of the object and generating an inspection light beam. After the inspection light beam passes through one of a plurality of filters, it is emitted to a beam splitter. A part of the inspection light beam is emitted to a shortwave filter while the other part is emitted to a longwave filter. The shortwave filter filters out the shortwaves of the first split light beam and the filtered first split light beam is emitted to a first sensing element. The longwave filter filters out the longwaves of the second split light beam and the filtered second split light beam is emitted to a second sensing element. The filter conversion module uses a conversion structure to alter the plurality of filters.