Metal Dome, is also known asSnap Domemade of stainless steel, is a important part of switch devices, which serves as a premium switch between the operator and product with the aid of metal dome conductivity. Meanwhile,metal dome provides operators premium tactile feedback due to the long life and stable resilience ( the dome return automatically after pressing). Surface processing includes gold plating, silver plating, and nickel plating, etc. Metal Domeis mainly used in membrane switch on rigid board, like printed circuit board.
Metal Dome- Working Principle
Metal Domeon membrane keypad is on conductive portion (Most are above golden finger of circuit board) of PCB board. Once metal dome is pressed, its center point of will sink in , contacting the circuit on PCB board to form circuit. Then the electricity flows through the wire so that the whole product are able to work normally.
Metal Dome -Category
According to different structures of product,Metal Domecan be divided into four kinds as following:
Single layer structure: This is the originally simplest structure. The metal dome is located beneath Mylar (a layer of adhesive PET), ensuring basic tactility and use with the air vent. Double layer structure: The difference between Double layer structure and Single conductive membrane is that bi-layer structure is equipped with an extra spacer, which is better paste the Mylar, contact circuit board and contribute good hand-touching. Besides, air vent on bi-layer conductive membrane is more effective to prevent PET layer from being scuffed by metal dome’s burrs.
EMI printing: There is a layer silver paste printed above Mylar, and that is ESD (Electrostatic Discharge Control). EMI is mainly used for preventing the target electric appliance from damage caused by static electricity, which is generated from the electrons and their peripheral products. Rubber glue: A layer rubber glue (silicone glue) is printed above Mylar or EMI layer. Therefore, this kind of product can firmly stick on PCB/FPC circuit board.