Similar with metal dome array, there’re three major parts for Polyester dome (Polydome):
Mylar: made of PET (Polyester), on top of Polydome, normal color is transparent/clear, so that you can see the conductive ink and Spacer. Normal thickness is 0.10mm and 0.125mm.
Conductive ink: under the embossed half circle area of Mylar, made of silver and carbon ink. The lower resistance of conductive ink is, more percentage of silver will be used and vice versa. Thickness of Silver: 0.004-0.006mm; Carbon: 0.005-0.006mm.
Spacer: also made of PET (Polyester), on bottom of Polydome, normal color is white, or transparent/clear.
Normal thickness is 0.15mm, 0.20mm.
And there’re extra two layers:
Rubber glue: On top of Mylar, and normal color is green, 0.125mm. It can be adhered to silicon/rubber keypad, membrane switch overlay firmly.
Glue on bottom: In fact, that extra glue was already with Spacer if customer want to stick Polydome on circuit board, so that you can’t separate that glue from Spacer.
Based on different combination of materials, there’re also three basic types of structures of Polyester dome for different assembly purpose, which is similar to metal dome array . Here are stack up and pictures details:
Normal Polyester dome (Polydome) stack up: There’s no glue either on top or bottom layer, so it needs to be fixed on the product by screws, registration pillar of keypad/ keyboard/PCB.
Click to download polyester dome structure (polydome stack up)
Customized structure of polyester dome (Polydome) is welcoming, such as add EMI/ESD reducing layer on top of polydome, different combination of different material. Please contact us today to send your requests for different stack up of polyester dome (Polydome)