Dispensing System Edge Detection for Circuit Board Alignment
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Solution Overview
Problem
Existing dispensing systems for viscous materials on circuit boards face inaccuracies when the dispensing area is not well-defined relative to fiducials, leading to suboptimal dispensing operations.
Innovation Solution
A method that locates and uses the edges of the substrate to orient the dispensing unit, allowing for accurate dispensing of lines or dots along or between edges without relying on fiducials, using a vision system to adjust the dispensing location and account for edge geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fiducials are used to align the circuit board with the dispensing unit, then the alignment process is well-defined, but the dispensing accuracy deteriorates when the dispensing area is not well referenced with respect to the fiducials
Solution Approach 1:
The patent extracts the alignment reference from fiducials (internal markers) to the edge of the substrate itself. By using the substrate edge as the primary reference feature, the system eliminates the intermediate fiducial marking step and directly references dispensing locations to the physical boundary of the workpiece, thereby improving accuracy when the dispensing area is not well-defined relative to traditional fiducials
Solution Approach 2:
The vision system acts as an intermediary between the substrate edge and the dispensing unit. It captures images of the substrate edge, determines the precise location and orientation of the edge, and uses this information to calculate and adjust the dispensing unit's positioning, thereby mediating the alignment process to achieve higher accuracy
2Adaptability or versatility
If the dispensing area is not referenced with respect to fiducials, then the dispensing operation can be performed, but the accuracy of the dispense operation deteriorates significantly
Solution Approach 1:
The system dynamically adjusts the dispensing unit's position and orientation based on real-time vision system measurements of the substrate edge. Rather than relying on pre-defined static fiducial locations, the system adapts to the actual physical boundaries of each substrate, allowing accurate dispensing even when the dispensing area extends beyond traditional fiducial references
Solution Approach 2:
The patent replaces the mechanical fiducial marking and measurement system with an optical vision system. The vision system captures images of the substrate edge and uses image processing to determine precise geometric features, substituting mechanical reference markers with optical field-based measurements for more flexible and accurate positioning
Data Source
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AI summary
A dispensing system for depositing material on an electronic substrate includes a frame, a dispensing unit gantry movably coupled to the frame, a dispensing unit coupled to the dispensing unit gantry, a vision system gantry coupled to the frame, and a vision system coupled to the vision system gantry. A controller is configured to manipulate the vision system with the vision gantry system to move to the position defined by a feature, to acquire an image of at least a portion of a feature, to search for an edge of interest along a center of the image, and to return a value indicating an offset of zero (0), which is interpreted as the location that is exactly as expected, and an offset that reflects where the edge of interest intersected that axis location.