Certain Implementation of the PCI(subscript S)C(subscript pm) and C(subscript pp)

製程能力指標C(下標 pm)及C(下標 pp)之應用

盧昆宏(Kuen-Horng Lu) ； 邱千惠(Chien-Hui Chiou)

《臺大管理論叢》 10卷2期 (2000/06) Pp. 205-226

摘要

製程能力指標是製程參數（製程期望值、標準差）及規格之一項沒有單位的函數，它可說是衡量製程是否合乎品質水準的一種簡單易懂的語言；它經常被用來判定產品在特定公差下是否合乎品質水準(Boyles, 1991)。然而，不少人僅透過樣本算出製程能力指標值就來判定製程能力，Montgomery(1985)等不少學者即指出如此進行判定製程是不適當的。因此，本文係針對C(下標 pm)指標的應用，於單製程時建構一C(下標 pm)的推薦最小值的判定程序；及於多重製程時提出以C(下標 pp)的多重製程績效分析圖的圖解法來分別判定多重製程是否合乎品質能力。透過本文所提之方法確實可以簡易且正確地判定出製程之品質能力。最後，透過半導體製程的兩個實際例子來說明C(下標 pm)判定程序及C(下標 pp)圖解法之應用。

關鍵字

製程能力指標 ； 推薦最小值 ； 多重製程績效分析圖 ； C(下標 pm)及C(下標 pp)指標

並列摘要

A process capability index (PCI) is a unitless function of the process parameters (μ, σ) and the process specifications (LSL, T, USL) designed to provide a common, easily understood language for quantifying the performance of a process (Boyles, 1991). It is used to determine whether a production process is capable of producing items within a specified tolerance. However, most people using the PCI simply consider the value of the index calculated from the given sample to make a conclusion on whether the given process is capable or not. Several authors (Montgomery (1985), Chou et al (1990) and Cheng (1992)) have pointed out that it is not an appropriate approach. Based on the application of Cpm index, this paper presents approaches for evaluating the quality capability of both the single process and multiple process in order to correctly and easily evaluate the quality performance of the process. Hence, this study constructs a testing procedure for RMV of Cpm to help judge whether a single process is capable or not, and proposes a graphic approach which uses the Cpp index for evaluating the quality performance of multiple processes. Finally, two numerical examples which illustrates the usage of the indices are provided.

並列關鍵字

Process Capability Index ； Recommended Minimum Value ； Multiprocess Performance Analysis Chart ； C(subscript pm) and C(subscript pp)