This time follow me to see the whole thickness of our metal dome array products. We have two types of the metal dome arrays: Single layer & Double layers. Please see the following structure:
1.For the Single layer structure: the whole thickness is equal to the thickness of the Mylar & metal dome. Normally the thickness of Mylar is 0.05mm.
2. For the Double layers structure: the whole thickness is the same as the Single layer structure. You can see from the picture, it is the double layers, but the spacer is parallel to the metal dome. So that you can ignore its thickness. Normally the thickness of the spacer is 0.075mm.
If there is enough space between your PCB & cover layer by the side of your button, It means over the thickness of the Mylar & Spacer (0.05+0.075=0.125mm), we recommend you to use the most popular double layers structure. Because there have ventilation between the domes, when you press the domes, the air can ran out easily. So it will be better with click feeling.
I think you are fully understand the advantage & disadvantage of the two structures now. For more information, please feel free to contact Best Technology.