Not so much an interface board as a whole new tested design for a LIDAR unit, including a unique patented optics setup and laser driver circuit, according to the complaint. Also testing, manufacturing, and characterization procedures and results and information on suppliers for the parts required. The PCB was just the component whose accidental disclosure lead them to conclude that Uber and Otto were using the stolen design. Since the PCB apparently dictates the position and orientation of the laser diodes and sensors, presumably it would only be useful if they copied the whole thing.