| Products are finished after all of the processes.The quality of finished products depends on every process.Product quality system is far from perfect during research and development of new products.At present,the manufacture mode is generally roll-to-roll.The yield of every process is evaluated by random inspection,while the yield of finished products by full inspection,leading to a large gap between the yield of every process and the yield of finished products.It is,therefore,important to perfrom quality analysis and control during research and development of new products in order to provide a solid foundation to establish quality system for mass production.In this work,the quality issues associated with projected capacitive touch sensors were systematically studied through quality analyses of the existing processes,mitigation suggestions for the improvements and effect confirmations of the executive frameworks.The evaluations for the current status in quality of finished products were performed by combining the analysis results from the yield of every process with those from the yield of finished products.The main research contents and conclusions are summarized as follows:(1)Through analyzing the current status of every process yield,the factors that caused the serious failures of the four key processes,namely,atmospheric lamination dry film,exposore,development and etching,were examined.Accordingly,the corresponding improvement schemes were suggested.Based upon the failure mode of abnormal patterns output after exposore,the input/output and failure modes were discussed along with the experimental optimizations.The best matching project for the light cover film and dry film for filament patterns under 70 milli Joule per square centimeter(mJ/cm2)was conducted.In order to overcome poor adhesion between the dry film and plastic film caused by the atmospheric lamination process,the best matching solution for the dry film and production parameters was found through design of experiment(DOE).In view of the problems involved in development process,the concentration estimation experiments were carried out.The best matching solution for obtaining the liquid concentration and production parameters was determined.For etching process,the standardized measures for solving the residual copper induced abnormal quality were made.All of these steps improved the quality of finished products.(2)Through analyzing the present situation for the yield of finished products,the causes and mitigations linked to open-circuit and short-circuit were studied.The materials scratching and peeling were the main causes of open-circuit and short-circuit.The effects of materials scratching on the properties of finished products were clarified and the suitable standards to accept metal film scratching were determined based on the understandings whether the main causes came from raw materials or manufacture processes.In an effort to resolve the materials peeling problem,the cross-cutting tests were conducted in the nine-rectangle-grid point locations by considering possible adhesion differences existed in different areas within the same roll of metal film raw materials.The influences of metal films adhesion on the shapes and properties of circuits,and the influences of current setting parameters on the adhesion of metal films were simultaneously investigated.(3)Through confirming the quality improvement and effect evaluation,whether the objectives in quality improvement of finised products had been reached was examined.According to the technical requirements for the fabrication technology of projected capacitive touch sensors,the factors that caused abnormal product quality were analyzed by applying 5 Why and fishbone diagram methods.Utilizing the define-measure-analyze-improve-control(DMAIC)tool,the improvement action was taken.The abnormal quality processes were taken place by employing 8D(i.e.,8-steps problem solving).In order to optimize the experimental parameters,the process failure mode effects analysis(PFMEA)mode and DOE were used to form the total planning template,and through a series of improvement actions the quality related problems involved during different stages of every process were solved.Finally,a set of standardized processes were established,which effectively enhanced the quality of finished products. |
