A circuit board.Sergio Flores/Bloomberg Surging demand for computer chips and related components amid the AI boom has boosted shares of ISU Petasys, a little-known manufacturer of printed circuit boards in South Korea, by 215% so far this year. The stock rise has made the company’s chairman, Kim Sang-beom, South Korea’s newest billionaire. Kim, 64, directly and indirectly owns 17% of ISU Petasys shares. He also has stakes in other ISU Group companies: ISU Specialty Chemical, ISU Chemical and bio...