SMT Re-Classification Engine for False Defect Reduction
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Solution Overview
Problem
Existing surface mount technology (SMT) systems face challenges in accurately determining the correct positioning of components on boards, leading to false defect calls and increased re-inspection at review stations.
Innovation Solution
A system comprising an optical inspection device, a review station, and a re-classification engine that uses machine learning algorithms, including ArcFace and GAN, to accurately classify components and reduce false defect calls by generating models for each class and determining class membership using feature extractors and classifiers, even when initial models are not available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical inspection methods are used to inspect component positioning, then inspection coverage is maintained, but false defect calls increase and measurement precision deteriorates
Solution Approach 1:
A re-classification engine is introduced as an intermediary system between the optical inspection device and the review station. This engine receives inspection data, applies machine learning models to re-evaluate component positioning, and provides corrected classification results. The intermediary resolves the contradiction by filtering out false defects through intelligent algorithms while maintaining inspection coverage, thereby improving measurement precision and reducing false defect calls simultaneously.
Solution Approach 2:
The patent replaces traditional mechanical/optical inspection methods with machine learning-based classification systems. Instead of relying solely on optical measurement thresholds that prone to false calls, the system uses neural networks and deep learning models to analyze component positioning. This substitution of mechanical inspection with intelligent algorithms enables more precise measurement while reducing false defect calls, directly addressing the technical contradiction.
2Reliability
If all inspected boards are sent to review station for manual re-inspection, then false defects are caught, but productivity decreases and loss of time increases
Solution Approach 1:
The re-classification engine implements a feedback mechanism that continuously learns from inspection results and refines its classification models. By analyzing confirmed defects and false calls, the system adjusts its decision boundaries and improves its accuracy over time. This feedback loop enables the system to maintain high reliability in defect detection while confidently reducing the number of false positives sent for manual review, thereby improving productivity.
Solution Approach 2:
The re-classification engine performs preliminary action by pre-screening and re-evaluating inspection results before they reach the review station. Using machine learning models, it preliminarily filters out false defects and only sends uncertain or confirmed cases for manual inspection. This preliminary processing reduces the workload at the review station, maintains high detection accuracy for real defects, and significantly improves overall processing throughput.
3Measurement precision
If models are generated for all classes, then classification accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the classification task into separate models for different component classes. Instead of using a single complex model to handle all classes, the system maintains dedicated models for each component type (e.g., resistors, capacitors, integrated circuits). This segmentation improves classification accuracy for each class while managing complexity through modular architecture, where each model can be independently trained and optimized for its specific component type.
Solution Approach 2:
The system implements dynamics by making model selection adaptive based on the specific class being inspected. The re-classification engine dynamically loads and switches between different class-specific models depending on the inspection data being processed. This dynamic model selection allows the system to maintain high accuracy for all classes while managing complexity through on-demand model loading and flexible architecture, rather than maintaining all models simultaneously in memory.
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 system reduces false defect calls and re-inspection rates by precisely determining component positioning, enhancing the accuracy of component classification and reducing unnecessary re-inspection.
Implementation Method 1
obtain data about a component by receiving reflected light of light radiated on the component
Data Source
AI summary
A system comprises: an optical inspection device configured to obtain first data, inspect whether or not the first data corresponds to a first class, and transmit an inspection result to a review station; the review station configured to transmit a re-inspection request for the inspection result to a re-classification engine; and the re-classification engine configured to: obtain the first data, determine whether or not a model for the first class is stored in one or more memories, upon a determination that the model for the first class is stored in the one or more memories, determine whether or not the first data corresponds to the first class using the model, upon a determination that the model for the first class is not stored in the one or more memories, determine whether or not the first data corresponds to the first class using second data corresponding to the first class.


