Lead Foot Angle Inspection Using Multiview Stereo Vision
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Solution Overview
Problem
Existing stereo vision systems are unable to accurately inspect the lead foot angle of all leads in Quad Flat Packages (QFP) and similar devices, as they are limited by the arrangement of cameras on a single plane, which prevents detection of lead angles that extend parallel to the camera plane, potentially leading to defective products due to bent leads.
Innovation Solution
A three-dimensional vision inspection system using three or five cameras arranged in an L-shape or cross-shape configuration, allowing for the capture of images from multiple orthogonal angles to determine lead foot angles by combining bottom and perspective views to reconstruct three-dimensional coordinates and calculate the acute angle between the lead foot line and a reference plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two or more cameras are arranged on one plane for stereo vision inspection, then the system can determine three-dimensional imaging and analysis of objects, but the system cannot detect lead foot angles of leads that extend parallel to the camera plane
Solution Approach 1:
The patent transitions from a two-dimensional planar camera arrangement to a three-dimensional spatial configuration by positioning at least one camera outside the plane formed by the other cameras. This dimensional change enables the system to capture leads extending in multiple directions, including those parallel to the original camera plane, thereby resolving the measurement limitation while maintaining three-dimensional imaging capability.
2Reliability
If cameras are arranged to inspect leads on all four sides of QFP devices, then complete inspection of all leads is achieved, but the system requires viewing the device at multiple angles which increases system complexity
Solution Approach 1:
The patent creates a universal camera arrangement where three or more cameras positioned in three-dimensional space can simultaneously inspect leads on all four sides of QFP devices. This multi-functional configuration eliminates the need for multiple separate viewing systems, achieving complete lead inspection while actually reducing overall system complexity through consolidation.
3Device complexity
If traditional stereo vision systems with cameras on one plane are used, then the system structure is simple, but the system cannot detect bent leads that extend parallel to the camera plane
Solution Approach 1:
The patent adds a third dimension to the camera arrangement by positioning at least one camera outside the plane of the other cameras. This minimal increase in structural complexity enables comprehensive detection of bent leads in all directions, significantly improving reliability without requiring a proportional increase in system complexity.
Data Source
AI summary
The present invention includes a system and method for three-dimensional imaging and analysis of electronic components. Specifically, it permits rapid and reliable inspection of the lead foot angle in integrated circuit packages. A first image capturing device, a second image capturing device and a third image capturing device are arranged in a “corner shape” or “L-shape.” The first image capturing device forms the corner and obtains an image of the bottom of the component. The perspective viewing angle of the second image capturing device and the perspective viewing angle of the third image capturing device are orthogonal to each other to allow accurate three-dimensional reconstruction of the lead angles and detection of flaws or bends.