The work includes pushing thin wires through holes only slightly larger in diameter than the wire itself, she said. Other tasks include laying Kapton tape, a type of industrial tape, in narrow crevices along the sides of components. While the work is easy for humans, robots are ill-suited for the task, the analyst said.
Other robotics experts took a similar view, saying cheap labor is still a better option for many device makers. Salaries at Foxconn's factory in Zhengzhou start at 1800 yuan (US$284) per month, and workers interviewed there have said the assembly line jobs require little training. Foxconn has expressed an interest in expanding into Indonesia, where labor costs could be even lower.
Robots are widely to manufacture automobiles, and are also used to build larger electronics products and for semiconductor manufacturing. But the "end effector" on robotic arms -- basically the robot's hand -- is often a simple, two-position device that lacks the dexterity of a human hand, which limits the use of robots in complex parts assembly.
"It's relatively easy for you [a human] to put a cable in a socket. You'll be able to fit it in every time," said Mikael Hedelind, a researcher at ABB, a major vendor of industrial robots. "But let's say you close your eyes and do the same thing, that's going to be much more difficult. (Robots) are very limited in visual sensing."
That's not to say robots can't do the job, according to Hedelind. He believes the technology needed for robots to build iPhones is available now, but says high costs and the way the robots would need to be programmed for each task can make their use impractical.
Apple may also play a role in the decision. Some products are designed as the outset for automatic assembly, he said. "How difficult it would be depends on the design of the phone." The rate at which product designs are refreshed also plays a role, since frequent changes mean robots must be reprogrammed more often.
Despite the challenges, Foxconn's investment in robots is likely to push the industry towards greater automation. George Zhang, senior principal scientist with ABB, said its plan to deploy a million robots is both aggressive and ambitious. He thinks Foxconn will eventually replace human workers for much of its electronic assembly.
Besides working tirelessly, robots are immune to many harsh environments where exposure to chemicals and noise can be harmful to people.