What are Silver Flex Membrane Switches?
Silver Flex membrane switches are the most common construction for flexible, custom membrane keypads. It is also the most popular membrane switch construction due to its affordability, especially when compared to bulky, costly electromechanical switch assemblies. Silver flex membranes switches feature very thin flexible layers of material, of which some layers utilize screen printed silver and carbon conductive inks, and are separated by an adhesive layer.
A metal dome copper flex membrane switch contains metal domes, or contacts, mounted to a copper flex substrate. The entire electronic module is encased inside a membrane switch assembly. Metal dome membrane switches are used when designers and electronic engineers desire a tactile response for users. This tactile response is achieved when users press the metal dome membrane switch, compressing the metal dome to the substrate conductor, and resulting in a snapping sound. The tactile response happens nearly simultaneously with the moment of contact.
Various actuation forces are possible, depending on the construction of the metal domes themselves. One advantage of using metal dome membrane switches is that they allow for designers and electronic engineers to choose the metal dome that will result in the actuation force that best suits the application.
Copper flex membrane switches are constructed using either polyester or polyimide as the base material. Copper flex membrane switches are produced by laminating a very thin sheet of copper to the flexible film substrate that is then chemically etched, leaving copper traces. Two disadvantages of copper flex membrane switches is that the process requires chemicals that are not environmentally friendly, and the process is less cost effective than the screen printing process involved in producing silver flex membrane switches.
Types of Copper Flex Membrane Switches
Copper membrane switches may be constructed in one of four ways:
Single-sided: conductive traces etched on one side of the film substrate
Double-sided: conductive traces etched on both sides of the film substrate
Multi-layer: numerous layers with conductive traces are stacked and laminated
Rigid-flex: a copper flex switch combined with a rigid membrane switch that is laminated