Multi-Angle Colored Light Board Inspection for Solder Joints
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Solution Overview
Problem
Existing board inspection methods for solder joints are prone to errors due to interference from surrounding conditions and non-typical shapes, leading to inaccurate assessments.
Innovation Solution
A board inspection method using multiple colored lights at different inclination angles to capture a color image, which is then verified with pre-measured height information to determine the quality of solder joints, ensuring accurate judgments regardless of surrounding conditions or non-standard shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single color light is used for inspection, then the inspection process is simple, but inspection errors occur due to interference from surrounding conditions and non-typical shapes
Solution Approach 1:
The inspection process is segmented into multiple stages: first inspection using color distribution from multi-color lighting, and second inspection using height information from 3D measurement. This segmentation allows each stage to focus on specific defect types, improving overall reliability while maintaining manageable complexity through systematic division of the inspection task.
Solution Approach 2:
The inspection transitions from two-dimensional color image analysis to three-dimensional height information analysis. By adding the height dimension through 3D measurement, the system can verify defects that appear suspicious in 2D color images, significantly improving inspection accuracy for non-typical shapes and reducing false positives.
2Measurement precision
If multiple colored lights at different inclination angles are used, then inspection accuracy improves, but device complexity increases
Solution Approach 1:
The multi-color lighting system serves multiple functions: it illuminates the inspection area for color distribution analysis, creates shadows for height perception, and provides verification data for defect validation. This multi-functionality reduces the need for separate inspection systems, managing overall device complexity while achieving high measurement precision.
Solution Approach 2:
Height information is measured in advance before the final inspection decision is made. This preliminary 3D measurement creates a reference database of solder joint heights that is used to verify defects identified in the color image inspection, improving precision while organizing the complexity into sequential, manageable steps.
3Productivity
If only color distribution is used for inspection, then the inspection process is fast, but inspection errors occur when solder joints have non-typical shapes
Solution Approach 1:
The inspection is segmented into a fast initial screening phase using color distribution and a verification phase using height information. This segmentation maintains high productivity through rapid color-based screening while improving reliability by applying 3D verification specifically to suspicious cases, reducing false positives without significantly slowing overall throughput.
Solution Approach 2:
Height information is measured preliminarily and stored for later verification. This allows the inspection system to quickly evaluate color distribution first, then use pre-measured height data to verify defects, maintaining fast inspection speed while ensuring reliable defect detection for non-typical solder joint shapes.
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 reduces inspection errors caused by external interference and non-typical solder joint shapes, enabling more precise defect detection in printed circuit boards.
Implementation Method 1
an inspection area including a solder joint of a component mounted on a board is provided with a first light having a first color, a second light having a second color different from the first color and a third light having a third color different from the first and second colors at a first inclination angle with respect to the board
Data Source
AI summary
In order to inspect a board, first, an inspection area including a solder joint is provided with a first light having a first color, a second light having a second color and a third light having a third color at a first inclination angle, a second inclination angle smaller than the first inclination angle and a third inclination angle smaller than the second inclination angle with respect to the board, respectively. Then, a color image of the inspection area is acquired according to the first light, the second light and the third light provided to the inspection area. Thereafter, it is inspected whether the solder joint is good or bad by using a color distribution in the color image. Then, the inspection result is verified by using pre-measured height information of the solder joint. Thus, an inspection error may be prevented.