Assuming your son will arrive in Shanghai via Pudong (PVG) airport there are 2 ATMs that I know of there that are relatively easy to use. The first is run by Citi and is immediately after Immigration before you go downstairs to baggage claim. The other (HSBC) is in Baggage Claim area across from the lower numbered carousels. Both work well and both take US based cards- the Citi ATM is my prefrerred ATM (not sure why). You are limited to 2000 RMB ($250) per day I think, if he needs more than that he will need to exchange it the old fashioned way- there is a currency exchange booth in baggage claim as well.

On a side note: the English used on the machines needs some thought as to what the requested task may be. For example "please dip your card"- after traveling 20+hours that always cracks me up.