In the face of challenges from its Chinese and South Korean rivals, Taiwanese manufacturers of thin-film transistor liquid crystal display (TFTLCD) panels have lost their advantage in the international supply chain. Taiwan’s panel industry is struggling with exorbitant investment costs, economic uncertainty, and numerous competitors. To take the initiative and capture the market, the case manufacturer seeks new technology transfer from an international company. However, manufacturing defects after the introduction of this technology have resulted in a more than 7% defective rate of electrical performance. Therefore, this study applies a systematic methodology that consists of defining, measuring, analyzing, improving, and controlling (DMAIC), to redesign the manufacturing processes, thereby improving yield rates, reducing scrapping costs, improving customer satisfaction, and strengthening competitive advantage. The results show that after the case company followed the DMAIC steps, the manufacturing flaw-small black pits, was identified and resolved. The incidence of defects decreased from 7.14% to 0%. The case study validated that the Six Sigma DMAIC methodology could help companies improve their product yield rate.