The front side of the U-shaped circuit board is occupied by components related to the laser sensor for tracking and a separate circuit board for the click switch. Though the power switch of the Magic Mouse is a slide switch, a sheet metal part is slid to push down the micro switch attached to the back side of the circuit board for power supply.
On the back side of the circuit board, there are a connector for the touch-sensor electrode (flexible printed circuit board) and some IC chips. The largest chip is Broadcom Corp's "BCM2042," a Bluetooth chip for mouse and keyboard, measuring 8.0 x 9.1mm2.
Located next to the BCM2042 is Silicon Storage Technology (SST) Inc's 2-Mbit serial flash memory (an 8-contact chip). When we carefully examined the circuit board, we found that a Bluetooth antenna is patterned on an edge of it.
The connector on the front side of the circuit board has 28 contacts and is about 14mm in width. Probably, it is a product with a contact pitch of 0.5mm. The IC chip placed next to the connector measures 4.5 x 4.5mm. Judged from its position and pattern, the chip seems to be a touch panel controller.
However, we could not determine the manufacturer of the chip, whose product number is "343S0487." The number does not match "BCM5974," the product number of Broadcom's touch panel controller used for the iPhone 3GS, which detects finger movements like the Magic Mouse, and the MacBook. It is possible that Apple developed a new dedicated chip for the Magic Mouse.