GE has a new 20kW hybrid laser arc welding (HLAW) system that's a lot more advanced than the welding methods we have now. Comparatively speaking, the new GE laser wields enough power to weld one-inch thick steel in a single pass. Current welding technologies need up to a half dozen passes.
Digitimes of Taiwan has their own guesses on who's making the iPhone. Seeing as Digitimes knows just about all the Taiwanese manufacturers, we'll say their guesses are pretty good.