From a distance, it’s probably not possible to tell if a piece of foam is conductive or not. Typically, conductive foam is like standard foam but with one essential and crucial difference: conductive foam is constructed with carbon mixed into the polymer. By introducing carbon into the foam, it adds incredibly high conductivity levels. This type of foam is ideal for many electrical engineers because the material allows a current to pass through the structure and away from components. In most cases, once carbon is added to make the material conductive, the foam has permanent conductive performance.
Conductive foam is an ESD-safe material with a surface resistivity of fewer than 103 ohms/sq. The material is also used because it offers less than 104 ohms/CMS volume resistivity. The conductive foam gives users a quicker transfer of static charges to a grounded source and adjacent conductive materials.
Faraday Bag
Polyethylene foam and carbon make up conductive foam, like a Faraday bag or cage. This type of EMI-resistant phone prevents the need for silver conductive bags, which significantly reduces the cost of manufacturing. It is crucial to remember that although conductive foam has many benefits, there are some drawbacks. Conductive foam can drain batteries when their contacts have paths within the foam.
Conductive foam is best implemented when the properties of a Faraday cage and conductor are essential. An example of this would be when shunting a component to a ground.