Key device and light guiding membrane switch

A key device, comprising:

• a bottom plate;
• a light guiding membrane switch on the bottom plate, wherein the light guiding membrane switch comprises a lower membrane layer, an upper membrane layer, and a light guiding spacing layer;
• and
• a keycap on the light guiding membrane switch;
• wherein, the upper membrane layer is disposed above the lower membrane layer and farther from the bottom plate than the lower membrane layer, the light guiding spacing layer is disposed between the lower membrane layer and the upper membrane layer, the light guiding spacing layer comprises an upper surface and a lower surface opposite to the upper surface, a reflective layer is securely fastened on the upper surface of the light guiding spacing layer, an adhering layer is adhered between the reflective layer and the upper membrane layer, and a position and a shape of the adhering layer correspond to a position and a shape of the reflective layer.