Profitable and more income are a company target for running a business.For a technology company, yield rate of a technology is essential for profitable or not. Higher yield rate will result in a greater gross margin for each selling of products. To have a high yield rate, sometimes, it is not straight forward at all. To find a yiled killer, sometimes it will take tremendoud efforts for searching and identification. Here, we present a case study for a yield rate improved for about ten times after the novel method is designed and then applied to the mass production process for further detailed.