Is it necessary to clear immigration on international connection through Shanghai Pudong airport?

I will be flying from Chicago to Singapore via Shanghai in Sept 2012. My flights are booked as a single itnerary through Orbitz. I will fly American airlines to Shanghai and then Singapore airlines to Singapore. There is only a 2.5hr layover scheduled for Shanghai. Will i need to clear customs (twice--'entering' and then 'leaving')? What is the process? Is there a transit/transfer area where I will need to check in? Where is this located? I've read on some travel websites (trip advisor & lonely planet) that the airport lacks clear signs for English speaking travelers, so I want to know what to expect and what to do before i arrive. thx