Integrated process capability analysis with an application in backlight module

Backlight application specializes in supplying light, with notable examples including liquid crystal display (LCD), hand-phone LCD, and PDA LCD. The integrated process capability and integrated process yield for cold cathode fluorescent lamp backlight are unknown. Process capability analysis is a highly effective means of assessing the process ability of backlight that meets specifications. A larger process capability index (PCI) implies a higher process yield, and lower expected process loss. Chen et al. [Int. J. Product. Res. 39 (2001) 4077], applied indices Cpu, Cpl, and Cpk to evaluate the integrated process capability for a multi-process product with smaller-the-better, larger-the-better, and nominal-the-best specifications, respectively. However, Cpk suffers from the weakness of being unable to reflect the specific process yield. This study selects index Cps to replace Cpk. Meanwhile, an integrated PCI for the entire backlight module is proposed, and the relationship between the PCI and process yield is described. A multi-process capability analysis chart, which reasonably accurately indicates the status of process capability for the backlight module, is designed for practical applications.