China-based Foxconn, which manufacturers products for Apple and other companies, says part of the problem with a shortage of iPhone 5, is that it’s so darn complicated to assembly.

“The iPhone 5 is the most difficult device that Foxconn has ever assembled.  To make it light and thin, the design is very complicated,” an unnamed official told “The Wall Street Journal” ( “It takes time to learn how to make this new device. Practice makes perfect. Our productivity has been improving day by day.”

The executive said Hon Hai has taken steps to improve its productivity and address scratches on the metal casings of some new iPhones that were shipped. Hon Hai has recently implemented a new quality check procedure to reduce the chance of damages.  However, the official told the “WSJ” that the iPhone 5 uses a new coating material that makes it more susceptible to scratching.