Meanwhile, the area of the main board in the iPhone 3G is about 1.5 times larger than the combined area of the two main boards in the 2G. When the main boards are compared in each circuit block, the mounting area of the newly-introduced RF processing circuit that supports 3G was increased by about 1.6 times.
The increased space was offset by the downsizing and modularization of the parts. For example, the transceiver circuits for wireless LAN and Bluetooth were replaced by a module manufactured by Murata Manufacturing Co Ltd, reducing the mounting area by about 60%.
In addition, the 3D acceleration sensor of STMicroelectronics, a joint venture of Italian and French companies, and the USB power supply control/charging control IC of Linear Technology Corp were downsized without changing their functions to reduce the mounting areas.
Furthermore, the outside dimensions of the application processor equipped with the ARM core, which carries the Apple logo and is supplied by Samsung Electronics Co Ltd, was downsized from 14 x 14mm to 13 x 13mm.
"They seem to have used the parts from the same suppliers to reduce costs and shorten the time required for the verification process," the engineer said.
Many modifications found on chassis covers
Many modifications were made to the designs that determine the appearance of the product. As mentioned earlier, the iPhone 3G uses a resin back cover for the chassis so as to provide flexibility for the layout of the antennas, while the iPhone 2G used metallic back cover. The use of a resin back cover seems to have contributed to a reduction in cost as well as the flexibility of the antenna layout.
However, the back cover of the iPhone 3G is reinforced by a metallic frame, and there is a trace of cutting work applied after molding. Cutting work increases manufacturing cost. But "external distortion of the chassis can be minimized by applying cutting work, compared with a product that is simply press-molded," said an engineer from a Japanese device manufacturer. This cutting work is probably showing the Apple's commitment to the external appearance.
In contrast, Apple seems to have put a priority on cost reduction when making modifications to the front cover (display area) of the chassis. In the display area of the iPhone 3G, the front cover, the touch panel and the LCD panel are separately mounted.
In the iPhone 2G, the chassis cover, the LCD panel and the touch panel were adhered together with resin. By laminating the parts, reflections of outside light and the backlight are reduced, and the display performance is improved compared with the method in which a layer of air is created between the LCD panel and the touch panel.
"But the panel bonding process that uses resin has a problem with the yield," the engineer said. "In this aspect, even the appearance-oriented Apple seems to have placed priority on cost."