PCB Solder Position Detection Using Luminance Difference Imaging
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Solution Overview
Problem
Existing methods for precisely detecting the solder position on a printed circuit board using a monochrome camera are hindered by the difficulty in distinguishing solder from other features, especially when silkscreen printing has similar luminance values, leading to inaccurate image data and challenging imaging conditions.
Innovation Solution
The method involves calculating luminance differences in image data acquired under varying imaging conditions to highlight the solder position, allowing for precise detection even with a simple, low-cost monochrome camera by setting conditions that maximize luminance differences between the solder and other areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a monochrome camera is used to detect solder position, then device cost is reduced, but measurement precision deteriorates because solder cannot be distinguished from other features with similar luminance values
Solution Approach 1:
The patent applies preliminary action by capturing multiple images of the solder paste at different positions (e.g., different heights or focal planes) before performing the detection. These preliminary images are then processed to extract the solder position information, enabling accurate detection with a simple monochrome camera without requiring complex real-time imaging systems.
Solution Approach 2:
The patent transitions from two-dimensional image analysis to three-dimensional position analysis by capturing images at multiple heights or focal planes. This dimensional change allows the system to distinguish solder from other features based on their spatial relationships across multiple planes, overcoming the limitation of luminance-based detection with monochrome cameras.
2Measurement precision
If multiple imaging conditions are used to improve solder detection accuracy, then measurement precision improves, but productivity deteriorates due to increased imaging time and data processing complexity
Solution Approach 1:
The patent performs preliminary imaging of the solder paste at multiple positions before the actual mounting process. This preliminary action allows the system to pre-calculate the solder position and store this information for use during high-speed mounting operations, thereby maintaining detection precision without slowing down production.
Solution Approach 2:
The patent creates a digital copy or model of the solder position based on preliminary images taken at multiple imaging conditions. This copied position information is then used for TOP mounting without requiring real-time multi-condition imaging during production, thus maintaining precision while preserving productivity.
3Manufacturing precision
If TOP mounting is implemented to correct for solder print shift, then manufacturing precision improves, but device complexity increases due to the need for additional imaging and calculation processes
Solution Approach 1:
The patent performs preliminary detection of solder paste positions and calculates the necessary mounting position corrections before the actual component mounting process. This preliminary calculation of TOP positions enables precise mounting without requiring complex real-time adjustment mechanisms during production.
Solution Approach 2:
The patent replaces complex mechanical positioning adjustment mechanisms with a computational approach. By using image processing and coordinate calculations to determine corrected mounting positions, the system achieves high precision TOP mounting through software-based position correction rather than mechanical adjustment.
Data Source
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AI summary
The present invention is a board production work method which includes a position detection process which detects an arrangement position of a detection target provided on a printed circuit board, and a work executing process which subjects the printed circuit board to predetermined production work based on the detected arrangement position, in which the position detection process includes an image acquisition step of imaging the printed circuit board under multiple imaging conditions and acquiring multiple items of original image data containing luminance values of each pixel arranged in two-dimensional coordinates, a difference calculation step of using two of the multiple items of original image data as calculation targets, calculating differences between luminance values of pixels with same coordinate values, and acquiring difference image data which is formed of luminance difference values of each of the pixels, and a position determination step of determining the arrangement position based on the difference image data. Accordingly, it is possible to precisely detect the arrangement position of the detection target on the printed circuit board through image processing while using a simple device configuration.