Root-cause analysis for integrated systems has become increasingly challenging due to their growing complexity. To tackle these challenges, machine learning (ML) has been applied to enhance root-cause analysis. Nonetheless, ML-based root-cause analysis usually requires abundant training data with root causes labeled by human experts, which are difficult or even impossible to obtain. To overcome this drawback, a semi-supervised co-training method is proposed for root-cause analysis in this article, which only requires a small portion of labeled data. First, a random forest is trained with labeled data. Next, we propose a co-training technique to learn from unlabeled data with semi-supervised learning, which pre-labels a subset of these data automatically and then retrains each decision tree in the random forest. In addition, a robust framework is proposed to avoid over-fitting. We further apply initialization by clustering and feature selection to improve the diagnostic performance. With two case studies from industry, the proposed approach shows superior performance against other state-of-the-art methods by saving up to 67% of labeling efforts.

The growing complexity of integrated systems makes root-cause analysis increasingly difficult. To address this challenge, advances in machine learning (ML) have been leveraged in recent years to design ML-based techniques for root-cause analysis. However, most of these methods require root-cause labels for defective samples obtained based on the analysis by human experts. In this article, we propose a multialgorithm two-stage clustering method with transfer learning for unsupervised root-cause analysis. First, a two-stage clustering method is proposed by applying multiple clustering methods to accommodate both numerical and categorical data and leveraging Silhouette score for model selection. Next, a double-bootstrapping method is proposed for data selection, transferring valuable information from a source product to a target product with insufficient data. In the first bootstrapping step, a random forest model is built to select effective source data. In the second bootstrapping step, clustering ensemble is applied to two-stage clustering to further improve the accuracy for root-cause analysis. Two case studies based on network products demonstrate the superior performance of the proposed approach compared to other state-of-the-art methods.

The increasing complexity of integrated systems has exacerbated the challenges associated with system diagnosis. To tackle these challenges, intelligent root-cause-analysis facilitated by machine learning has been proposed in recent years. However, most of these methods rely on a large amount of data with root-cause labels, which are often either not available or difficult to obtain. In this paper, we propose a semi-supervised root-cause-analysis method with co-training, where only a small set of labeled data is required. Using random forest as the learning kernel, a co-training technique is proposed to leverage the unlabeled data by automatically pre-labeling a subset of them and retraining each decision tree. In addition, several novel techniques are proposed to avoid over-fitting and determine hyper-parameters. Two case studies based on industrial designs demonstrate that the proposed approach significantly outperforms state-of-the-art methods by saving up to 43% of labeling efforts by human experts.

The increasing complexity and high cost of integrated systems have placed immense pressure on root-cause analysis and diagnosis. In light of artificial intelligence and machine learning, a large amount of intelligent root-cause analysis methods have been proposed. However, most of them need historical test data with root-cause labels from repair history, which are often difficult and expensive to obtain. We propose a two-stage unsupervised root-cause-analysis method in which no repair history is needed. In the first stage, a decision-tree model is trained with system test information to cluster the data in a coarse-grained manner. In the second stage, frequent-pattern mining is applied to extract frequent patterns in each decision-tree node to precisely cluster the data so that each cluster represents only a small number of root causes. The proposed method can accommodate both numerical and categorical test items. A combination of the L-method, cross validation, and Silhouette score enables us to automatically determine all hyperparameters. Two industry case studies with system test data demonstrate that the proposed approach significantly outperforms the state-of-the-art unsupervised root-cause-analysis method.

The increasing complexity of integrated systems has exacerbated the problems associated with root-cause analysis. Leveraging advances artificial intelligence, a large amount of intelligent root-cause-analysis methods have been proposed in recent years. However, most of these methods rely on root-cause labels from repair history for defective samples, which are often expensive to obtain. In this paper, we propose an unsupervised root-cause-analysis method that utilizes transfer learning. A two-stage clustering method is first developed by exploiting model selection based on the concept of Silhouette score. Next, a data-selection method based on ensemble learning is proposed to transfer valuable information from a source product to improve the root-cause-analysis accuracy on the target product with insufficient data. Two case studies based on industry designs demonstrate that the proposed approach significantly outperforms other state-of-the-art unsupervised root-cause-analysis methods.

The growing complexity of circuit boards makes manufacturing test increasingly expensive. In order to reduce test cost, a number of test selection methods have been proposed in the literature. However, only few of these methods can be applied to black-box test-cost reduction. In this article, we propose a novel black-box test selection method based on Bayesian networks (BNs), which extract the strong relationship among tests. First, the problem of reducing the black-box test cost is formulated as a constrained optimization problem. Next, multiple structure learning and transfer learning algorithms are implemented to construct BN models. Based on these BN models, we propose an iterative test selection method with a new metric, Bayesian index, for test-cost reduction. In addition, averaging strategies are applied to enhance the reduction performance. Finally, a robust model selection framework is proposed to select the optimal BN model for test-cost reduction. Two case studies with production test data demonstrate that when no prior information is provided, our proposed approach effectively reduces the test cost by up to 14.7%, compared to the state-of-the-art greedy algorithm. Moreover, our proposed approach further reduces the test cost by up to 7.1% when prior information is provided from similar products.

The increasing complexity and high cost of integrated systems has placed immense pressure on root-cause analysis and diagnosis. In light of artificial intelligent and machine learning, a large amount of intelligent root-cause analysis methods have been proposed. However, most of them need historical test data with root-cause labels from repair history, which are often difficult and expensive to obtain. In this paper, we propose a two-stage unsupervised root-cause analysis method in which no repair history is needed. In the first stage, a decision-tree model is trained with system test information to roughly cluster the data. In the second stage, frequent-pattern mining is applied to extract frequent patterns in each decision-tree node to precisely cluster the data so that each cluster represents only a small number of root causes. In additional, L-method and cross validation are applied to automatically determine the hyper-parameters of our algorithm. Two industry case studies with system test data demonstrate that the proposed approach significantly outperforms the state-of-the-art unsupervised root-cause analysis method.

The ever-increasing complexity of integrated circuits inevitably leads to high test cost. Adaptive testing provides an effective solution for test-cost reduction; this testing framework selects the important test items for each set of chips. However, adaptive testing methods designed for digital circuits are coarse-grained, and they are targeted only at systematic defects. To incorporate fabrication variations and random defects in the testing framework, we propose a fine-grained adaptive testing method based on machine learning. We use the parametric test results from the previous stages of test to train a quality-prediction model for use in subsequent test stages. Next, we partition a given lot of chips into two groups based on their predicted quality. A test-selection method based on statistical learning is applied to the chips with high predicted quality. An ad hoc test-selection method is proposed and applied to the chips with low predicted quality. Experimental results using a large number of fabricated chips and the associated test data show that to achieve the same defect level as in prior work on adaptive testing, the fine-grained adaptive testing method reduces test cost by 90% for low-quality chips and up to 7% for all the chips in a lot.

Tunable analog/RF circuit has emerged as a promising technique to address the significant performance uncertainties caused by process variations. To optimize these tunable circuits after fabrication, most existing post-silicon programming methods are developed by using real-valued performance metrics. However, when measuring a performance of interest on silicon, it is often substantially more expensive to obtain a real-valued measurement than a binary testing outcome (i.e., pass or fail). In this article, we propose a Gaussian Process Classification model to capture the binary performance metrics of tunable analog/RF circuits. Based on these models, post-silicon programming is cast into an optimization problem that can be solved by a novel Bayesian optimization algorithm. Moreover, measurement noises are further incorporated into our proposed post-silicon programming to produce a robust circuit. Two circuit examples demonstrate that the proposed approach can efficiently program tunable circuits with binary performance metrics while other conventional methods are not applicable.

The growing complexity of circuit boards makes manufacturing test increasingly expensive. In order to reduce test cost, a number of test selection methods have been proposed in the literature. However, only few of these methods can be applied to black-box test-cost reduction. The conventional greedy algorithm, which selects the most important tests by considering both strong and weak relationships among tests, suffers from overfitting. In order to overcome overfitting, we propose a novel black-box test selection method based on a Bayesian network model. First, the problem of reducing black-box test cost is formulated as a constrained optimization problem. Next, a score-based algorithm is implemented to construct the Bayesian network for black-box tests. Finally, we propose a Bayesian index with the property of Markov blankets, and then an iterative test selection method is developed based on our proposed Bayesian index. The proposed approach ensures that only the strong relationships among black-box tests are used for test selection so that this approach is more robust to overfitting. Two case studies with production test data demonstrate that the proposed approach effectively reduces test cost by up to 14.7%, compared to a conventional greedy algorithm.

The ever-increasing complexity of integrated circuits inevitably leads to high test cost. Adaptive testing provides an effective solution for test-cost reduction; this testing framework selects the important test items for each set of chips. However, adaptive testing methods designed for digital circuits are coarse-grained, and they are targeted only at systematic defects. In order to incorporate fabrication variations and random defects in the testing framework, we propose a fine-grained adaptive testing method based on machine learning. We use the parametric test results from the previous stages of test to train a quality-prediction model for use in subsequent test stages. Next, we partition a given lot of chips into two groups based on their predicted quality. A test-selection method based on statistical learning is applied to the chips with high predicted quality. An ad hoc test-selection method is proposed and applied to the chips with low predicted quality. Experimental results using a large number of fabricated chips and the associated test data show that to achieve the same defect level as in prior work on adaptive testing, the fine-grained adaptive testing method reduces test cost by 90% for low-quality chips, and up to 7% for all the chips in a lot.