The iPhone 4 also is unique in the number and variety of small assemblies used in the handset.
"There are a lot of small complex assemblies with flex circuits and things hanging off them and an awful lot of small screws," Carey said. "Some of these parts may self-align, but many of them look like parts requiring fairly meticulous assembly," he said.
"I think it requires a lot of human capital with a lot of people at a lot of tables in what is effectively by-hand assembly," he said. "You have to carefully hand fit these little flex parts because they are not amendable to a lot of automated assembly," he added.
"I have never toured a Foxconn factory [where the iPhone is made], but I have toured a Citizen watch factory, and I think Apple is doing what the watch industry figured out years ago," Carey said. "The human capital it costs to crank out millions of these [handsets] is pretty amazing," he said.
Apple has come under scrutiny for its use of low wage labor at Foxconn where a handful of workers have committed suicide, reportedly due to working conditions. Foxconn is reportedly looking to move operations from increasingly expensive coastal China areas to the China interior where wages may be lower.
Ironically, the by-hand assembly could cost Apple a premium compared to competing handsets that use more automation but are not as slim.
"Nokia phones look more designed for automated assembly and Samsung and HTC handsets may be somewhere in between," said Carey. "Things designed for automated assembly cannot achieve as much miniaturization because the human hand can pack things in the way machines can't," he said.
Subassemblies in the iPhone 4 Source: UBM TechInsights