Finally, we started to break down the main board. The first impression of the main board was that its metal covers for reducing electromagnetic noise stood out. Especially, the bottom side, which was in contact with the case, was completely covered with a large metal cover.
In the iPhone 4S, metal rails were soldered on the surface of its main board, and metal covers were fitted into them. On the other hand, the metal covers of the iPhone 5 were directly soldered to the sides of its main board as if the board was wrapped with metal shells. Probably, Apple Inc wanted to increase an area on which electronic parts can be mounted.
The shape and size of the iPhone 5's main board were similar to those of the iPhone 4S' main board. However, connectors of the iPhone 4S' were concentrated on the bottom side while those of the iPhone 5 were concentrated on the top side. It is probably because the iPhone 4S is assembled from the top side and the iPhone 5 is assembled from the bottom side.
There were many power amplifiers and filters for mobile communication on the main board because the iPhone 5 supports LTE as a mobile communication method.