Continued from [iPad 2 Teardown (2)] Iron Prevents Cracking of Glass
A touch panel was attached to the back side of the iPad 2's front glass as in the case of the first-generation iPad.
The front glass of the iPad was strengthened by attaching a resin frame around its touch panel. On the other hand, the iPad 2 did not have this frame, and its front glass was directly attached to the chassis with a double-sided tape.
When we removed the LCD panel after the front glass, there were a main board covered with a metal cover for blocking electromagnetic waves and three lithium (Li)-polymer rechargeable batteries inside.
We disassembled the LCD panel for just in case. Its specifications are the same as those of the iPad, and it seemed that the number of optical films did not change, either.
While the internal structure of the iPad is almost bilaterally symmetric, that of the iPad 2 is not. To realize the slim body of the iPad 2, Apple reduced the thickness of the Li-polymer rechargeable battery from about 4.2mm to 2.5mm. Because the capacity of the battery was reduced for the slimness, the company increased the number of batteries from two to three to ensure an equivalent or higher capacity.
"To arrange three batteries, Apple probably had no choice other than to use the asymmetric structure," an engineer said.
An asymmetric structure sometimes upsets weight balance, but we did not feel any imbalance when holding the iPad 2. Probably, Apple designed it in consideration of the balance. A resin frame used to protect the batteries of the iPad was not employed for the iPad 2 in the aim of reducing its thickness and weight.
What impressed us most was that many double-sided tapes were used to fix codes and small components inside probably to cope with vibration. The Li-polymer rechargeable batteries were also directly attached to the chassis by using a double-sided tape.
To fix the main board, Apple used both screws and a double-sided tape. The adhesive force of the double-sided tape is so strong that the main board was bent when being removed from the chassis.
However, unlike Chinese makers' iPad look-alikes, which use double-sided tapes in a careless way, the iPad 2 did not look cheap despite the heavy use of double-sided tapes. Its internal structure was well organized, and there seemed to be no wasted space. It was probably designed in consideration of the thickness of the tape, etc.
The main board has a long and thin shape. When the metal cover was removed from the main board, there were the "A5," which stacks a processor and DRAM, Toshiba Corp's flash memory, a power supply control chip with Apple's logo and so forth.
The wireless LAN/Bluetooth function of the iPad 2 was modularized into a small circuit board, which is mounted on the main board via a connector. This is basically the same structure as that of the iPhone and the first-generation iPad.
When an engineer who knows well about electronic parts and sensors looked at the main board, he said, "There is no acceleration sensor and no gyroscope."