The Magic Mouse mainly consists of the top cover, top frame, circuit boards, bottom frame and bottom cover. The white resin top cover, which seems to be made of polycarbonate, is 2.45mm in thickness and equipped with an electrode of the touch sensor (flexible substrate). The area of the flexible substrate is about 80% that of the mouse.
The frame that supports the top cover serves as part of the hinge mechanism so that the entire chassis can be used as a click button. The flexible substrate is sandwiched between the top cover and the top frame, which are attached together by double-sided tape.
The other part of the hinge mechanism is the bottom frame that is also used as a battery case. The bottom cover and the bottom frame are fixed together by double-sided tape, too.
A U-shaped circuit board is screwed on the bottom frame, and the electrodes for the battery case are soldered on the circuit board. But Omron Corp's microswitch, which works as a click switch, is provided as another circuit board so that the U-shaped circuit board is not damaged by clicking.
The circuit board for the click switch has a spring terminal and touches the aluminum-alloy bottom cover.
"Apple intends to prevent the sensitivity of the touch sensor from lowering by connecting a palm to ground," said an engineer who is well-versed in touch panels.
The aluminum bottom cover is held by the thumb and medical finger. So, it is possible that the bottom cover is made of aluminum not only for design consideration.
The white resin top cover, which seems to be made of polycarbonate, is 2.45mm in thickness and equipped with an electrode of the touch sensor (flexible substrate) on its back. The area of the flexible substrate is about 80% that of the mouse. (Click to enlarge)
The frame that supports the top cover has bearings for the hinge mechanism. The holes of the front bearings (right) are oval shaped so that shafts can move up and down. And the holes of the rear bearings (left) are round shaped. One of the bearing broke while the mouse was being disassembled. (Click to enlarge)
The shafts for the hinge mechanism can be found in the bottom frame that has a battery case. (Click to enlarge)
The click switch and the circuit board. The L-shaped metal bar seen in the center works as a spring that lifts up the chassis. (Click to enlarge)
The click switch is provided as a separate board and firmly fixed by screws. (Click to enlarge)
The click switch has a spring terminal on its back so that a palm is grounded via the aluminum bottom cover. (Click to enlarge)