What are the key factors in locating new high-tech plants? Good schools? Temperate climate? Union attitudes? University of California (Berkeley) researchers, in a recent study for the National Science Foundation, say high-tech firms serving defense-type industries first seek locations near a major university - then good transportation and installations, such as industrial parks. Space-oriented manufacturers are usually located adjacent to or near each other. Manufacturers involved with semiconductors, computers, optics, and high-tech components tend to cluster together. But other types of companies - paint, chemicals, fertilizers - tend to be widely dispersed.