Membrane switch/membrane keypad,  is built from PET/PC and PSA. PCB can also be used as the base for a switch. It can be tactile or non-tactile, depending on the design. Tactile one provides a physical "click" when the user pushes it. Non-tactile one has longer lives, but lack physical feedback to the user. Rubber keypad can be added to the top of it as well. Membrane switches are used in many areas, like medical, gaming, aviation, boating, equipment, appliances, printers and public information panels etc. Membrane switches have many advantages over other switches. They are thin and compact, have a low cost, are versatile and durable, user friendly and are moisture and dirt resistant. Additionally, they come in many visually-pleasing styles and colors suitable for any need. 

Membrane Switch Keypad General specifications
Vmax *0V (DC)
Imax **0mA
Contact Resistance: *0ohm - **0ohm
Insulation Resistance: **0m (at **0V)
Dielectric Withstand: **0Vrms (****0Hz)
Contact Bounce: Less than 5ms
Operating Temperature: **5 C ~ + *5C
Allowable Humidity: *5%
Advantages
High reliability
Long life
Low cost
Dust proof
Water proof
Rust proof Easy installation Design flexibility.