[New iPad Teardown (4)] Double-sided Main Board
Continued from [New iPad Teardown (3)] Larger-area, Thicker Battery
Finally, we started to compare the main boards of the iPad 2 and the new iPad. We made an unexpected mistake when removing the main board of the "Wi-Fi" model of the new iPad. When we were pulling the connector located below the main board, it broke into pieces. Judging from the structure of the connector fitted in a socket, the connector seemed to be fitted in the socket from above.
So, for the "Wi-Fi + 4G" model of the new iPad, we carefully pulled the connector upward by inserting a flat-head screwdriver into the gap between the socket and the connector. Though we successfully took out the connector without damaging it, the socket on the main board became shaky probably because of the force applied to it. When we were taking a picture, the socket dropped off from the board.
"Connectors used in recent mobile devices are locked so that they are not dropped off," an engineer of a connector maker said. "If we try to remove them without knowing it, we damage them in many times. I myself do not know much about some of the other companies' connectors."
The main board of the new iPad was slightly smaller than that of the iPad 2. The largest difference between them was that the iPad 2 had a single-sided main board and the new iPad had a double-sided main board. While the iPad 2's main board was firmly attached to the bottom half of the case with a double-sided tape, the new iPad's main board was not so firmly attached.
On the back of the new iPad's main board, there was a chip package that seemed to be a DRAM. In the iPad 2, the "A5" processor and a DRAM are mounted as a PoP (package on package).
The new iPad does not use a PoP probably for dissipating heat from its "A5X" processor. In the new iPad, a metal heat sink is attached to the A5X bare chip, and the heat from the chip is conducted to a metal cover used as a measure against electromagnetic noise via a thermally-conductive sheet.
By tearing down the new iPad, we found that top priority was placed on ensuring a space for its large-capacity battery. Its main board had a smaller size and was placed near a side of the case. And all the functions were realized in small spaces near the rim of the new iPad.
Furthermore, to reduce costs, the thin-wire coaxial cable used for the iPad 2 was replaced with a flat cable for the new iPhone.