Two supply chain sources said display panel production suffered a setback after the backlight that helps illuminate the screen had to be revised, putting screen assembly on hold for part of June and July. One said Apple, aiming for the thinnest phone possible, initially wanted to cut back to a single layer of backlight film, instead of the standard two layers, for the 4.7-inch screen, which went into mass production ahead of the 5.5-inch version.
Apparently, the initial design was not bright enough and the backlight had to be redesigned to fit in the extra layer. The output issue has been resolved and suppliers are reportedly working 'flat-out' to make up for the lost time. Japan Display, Sharp, and LG Display are all supplying screens for the next generation iPhone.
Apple is expected to unveil the iPhone 6 at a media event on September 9th. Please follow iClarified on Twitter, Facebook, Google+, or RSS for updates.