The materials used in the flexible circuit of membrane switches are insulating films, adhesives and conductors. The insulating film forms the base layer of the circuit and the adhesive bonds the copper foil to the insulating layer. In a multilayer design, it is bonded to the inner layer. They are also used as protective masks to separate the circuit from dust and moisture, and to reduce stress during the flexing period. Copper foil forms the conductive layer. Membrane switch (flexible circuit) data which switches in some films, take the rigid component is made of aluminum or stainless steel, they can supply the volatility of the size of the components and wires to settle supply physical support, as well as the release of stress. The adhesive bonds the rigid member with the flexible circuit together. There is also a data, sometimes used in flexible circuit, it is the bonding layer film, it is coated on the two sides of the insulating film coated with adhesive. The adhesive layer provides protection of the case and electronic insulation, and can eliminate a layer of film and a multilayer capable of having fewer layers of bonding. There are many kinds of insulating film materials, but the most common ones are poly imide and polyester data.