Creating an entirely new design meant inventing an entirely new technology.

When we envisioned the new iPhone, we landed on a remarkably thin and light design. But it’s nearly impossible to make a device so thin and so light without sacrificing features or performance.

We could have taken the easy way out and designed something more reasonable and less remarkable. But we didn’t. If the technology didn’t exist, we invented it. If a component wasn’t small enough, we re-imagined it. If convention was standing in the way, we left it behind. The result is iPhone 5: the thinnest, lightest, fastest iPhone ever.

iPhone 5 is just 7.6 millimeters thin. To make that happen, Apple engineers had to think small, component by component. They created a nano-SIM card, which is 44 percent smaller than a micro-SIM. They also developed a unique cellular solution for iPhone 5. The conventional approach to building LTE into a world phone uses two chips — one for voice, one for data. On iPhone 5, both are on a single chip. The intelligent, reversible Lightning connector is 80 percent smaller than the 30-pin connector. The 8MP iSight camera has even more features — like panorama and dynamic low-light mode — yet it’s 20 percent smaller. And the new A6 chip is up to 2x faster than the A5 chip but 22 percent smaller. Even with so much inside, iPhone 5 is 20 percent lighter and 18 percent thinner than iPhone 4S.

Source: http://www.apple.com/iphone/design

A 2012 iPhone 5 perspective to consider.