Fault Region Localization: Product and Process Improvement Based on Field Performance and Manufacturing Measurements

Customer feedback in the form of warranty/field performance is an important direct indicator of quality and robustness of a product. Linking warranty information to manufacturing measurements can identify key design and process variables that are related to warranty failures. Warranty data have been traditionally used in reliability studies to determine failure distributions and warranty cost. This paper proposes a novel fault region localization methodology to link warranty failures to manufacturing measurements (hence, to design and process parameters) for diagnosing warranty failures and to perform tolerance revaluation. The methodology consists of identifying relations between warranty failures and design/process variables using rough sets-based analysis on training data consisting of warranty information and manufacturing measurements. The methodology expands the rough set-based analysis by introducing parameters for inclusion of noise and uncertainty of warranty data classes. Based on the identified parameters related to the failure, a revaluation of the original tolerances can be performed to improve product robustness. The proposed methodology is illustrated using case studies of two warranty failures from the electronics industry. Note to Practitioners-Warranty failures are indicative of the performance and robustness of the product. Warranty failures, especially those that occur early (e.g., within six months after sale), can be caused by interactions between various design and process characteristics of the individual components of the product. Due to the large number of components and the interactions between them, it is difficult to identify all of these relations during design. Furthermore, it is difficult to replicate actual product usage in the field during the design stage. The methodology proposed in this paper integrates a product´s warranty failure information with that of measurement data collected during manufacturing, to identify relevant des- - ign and process variables related to the failures. It also identifies the warranty fault region within the original design tolerance window for the parameters. This can help in avoiding warranty failure(s) through design changes and/or tolerance revaluation. The methodology was applied in the electronics and semiconductor industries