Key assembly

A key assembly configured for being disposed in an electronic device, comprising:

• a switch component, disposed in a case of the electronic device;
• and
• a flexible button, having a pressing portion, a shaft portion, at least a water-resistant portion and an actuating portion, wherein the flexible button is made of rubber, the pressing portion, the shaft portion, and the actuating portion are an integrally formed structure, the pressing portion is exposed from the case, the shaft portion connects the pressing portion and the actuating portion and passes through a through hole of the case, the water-resistant portion is connected to the shaft portion and covers the through hole, the actuating portion is disposed in the case and aligned to the switch component, and the flexible button further comprises a first cavity located in the pressing portion, a first communicating channel located in the shaft portion, and a second cavity located in the actuating portion, the communicating channel communicates the first cavity with the second cavity, and wherein when a force is applied to the pressing portion, the pressing portion is compressively deformed and a size of the first cavity is reduced,
• after air in the first cavity is squeezed, the air flows into the second cavity via the communicating channel so that the actuating portion is expansively deformed and the second cavity is expanded from a first volume to a second volume larger than the first volume so as to actuate the switch component.