The manager of semiconductor production line desires to know if the manufacturing procedure of silicon wafer is stable or not. As a quality engineer, you gathered one sample measurement from each of randomly chosen three products every day, and you collected data for 25 days in a row. You are needed to answer the following questions:
1. If you want to make control charts, what kind of control charts would you plan to choose? Discuss the reasoning behind your answer.
2. Are there any assumptions before using control charts? You don't have to test for these assumptions as part of this question.
3. Assume the assumptions are met, develop the control chart using the original data. Is the process in control? Discuss your findings.
4. What should you recommend the manager do next?
5. If the manager feels that any measurement over 60 or below 10 is not tolerable. What is the C
p and Cpk for this process? What is the DPMO level associated with this process?
6. Explain "common causes" and "special causes" and give at least one example for each. In this case, based on the control chart you developed, explain/identify the trends that can be associated with "common cause" and "special cause" variations.