MEXICO CITY — Former Univision exec producer Joshua Mintz has joined Azteca America as director of programming. U.S. venture of Mexico’s No. 2 net TV Azteca is bulking up its U.S. executive ranks.Mintz reports to Azteca America CEO Adrian Steckel and will be based in Los Angeles at flagship L.A. station KAZA-TV. Azteca America aims to open corporate offices in Los Angeles this year. Mintz has 20 years of experience, including a stint as a programming director at Mexico’s top net Televisa and, until 2005, as executive producer at Univision, where his productions included “Selena Vive!” one of the highest rated Spanish-language TV specials.