液晶顯示面板(LCD)是目前手機最主要的元件，面板的功能在於顯示，讓手機資訊明確傳達給使用者，在目前多功能手機的世代，是最重要的溝通界面。目前的LCD主體是由玻璃基板所組成，內部有金屬線路、絕緣層、彩色濾光片(Color filter)、液晶(Liquid Crystal)等重要元件，另外加上有偏光片、驅動IC、背光模組、鐵框等元件組成LCD模組(LCM)。由於手機面板在市場上的產品生命週期，遠比液晶電視用面板來的短，為了吸引客戶，手機的設計必需多樣且多變，故朝向輕、薄、小等方向設計，這也導致LCD玻璃要愈做愈薄，例如從早期的1.1mm厚度到現今主流的0.3mm及0.2mm厚度。因手機在使用上經常會不小心掉落或因為太薄放在口袋時壓到而造成破裂，故從0.4mm厚度的產品開始，客戶會開始要求玻璃的強度品質。由於上述原因手機變得薄、小且形狀特殊，導致在手機機構設計上有許多的限制，尤其在機構保護LCD的能力上變得很薄弱，不僅於此，LCD的厚度被要求的更薄，而螢幕尺寸設計愈來愈大，從早期1.5”~1.8”到現今2”~3.5”，造成薄化的LCD產品在強度上面臨極大的挑戰。
本研究以某中小型TFT LCD面板廠為例，在市場景氣面臨巨變的環境之下，個案公司運用六標準差DMAIC的方法，企圖改善LCD彎曲強度，從傾聽客戶聲音並結合公司策略開始，進行各項實驗以及應用統計方法分析，找出重要影響因子並進行優化與控制，最後，監控指標的改善成效以及評估整體的效益。

Liquid Crystal Display, LCD, is the major component of a mobile phone and serves to display information to end users for operation instructions. It is the most important interface in the age of multi-functional mobile phone. It is mainly made of glass with other components, such as layout of metal, insulating layer, color filter, and liquid crystal. LCD module, LCM, consists of LCD, polarize, IC driver, back light module, housing, etc. Because the product life of mobile LCD is shorter than that of TV LCD, the design of mobile phone has been innovated with more variety in order to attract more users. New mobiles are lighter, thinner, and smaller.
LCD thickness has been thinned out from 1.1 mm to the current 0.2 mm and 0.3 mm. Thin glass LCD of mobile phone breaks easily when dropped and bent due to incautious usage. Therefore, mobile phone manufacturers begin to demand more LCD strength for 0.4 mm LCD. There are a number of limits in machinery design because mobile becomes smaller and thinner, whose design would inevitably weaken LCD protection. Besides, LCD screen has become bigger in the present design, with screen sizes from 1.5” ~ 1/8” to the current 2”~3.5” . In view of these factors, thin LCD product designs confronts huge challenges in LCD strength.
This case study discusses how a small and medium-sized TFT LCD manufacturer sought to improve LCD bending strength by applying Six Sigma when facing economic recession. They started from redefining company strategies, listening to customers, determining critical quality, making experiments, applying statistical analysis, finding main effect factors to optimization by response surface method. Finally, controlling critical quality and confirming benefit of total cost.

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