The Adafruit PCB Manufacturing Line is quite impressive. Ladyada (Limore Fried) goes through the entire process start to finish describing what each piece in the line does. Questions from the MIT students at the end are interesting also.
"Ladyada is the hacker @ Adafruit, founded in 2005 by MIT hacker & engineer Limor "Ladyada" Fried. Her goal was to create the best place online for learning electronics and making the best designed products for makers of all ages and skill levels. Adafruit has grown to over 100+ employees in the heart of NYC with a 50,000+ sq ft. factory. Adafruit has expanded offerings to include tools, equipment and electronics that Limor personally selects, tests and approves before going in to the Adafruit store."