Louvered Contact Band
The final level of achievable power transmission when using crown spring contact band is dependent upon several parameters. Some of which are dependent upon best practice, the choice of material and quality of workmanship. Whereas others are variable by design and adoptable to application requirements.
The most common metals used are copper(1), aluminum(0.75) or brass(0.6). The numbers in brackets indicate a ball park figure for determining conductivity factors. Based on copper having a factor 1. Nevertheless it is possible to use any conductive material for the connector components. Silver is the most common surface plating for high current applications. Whereas Gold will mainly be used for applications in aggressive environment. Although there are further reasons for gold platings. Such as in applications underlying micromotion between the connector components.
The current loading capability of the crown spring bands themselves is mainly influenced by their physical design. Also by the base material, the material thickness, surface plating and by the number of contact points per defined footprint. For two contact bands with all parameters being the same but with different number of contact points the one with more contact bridges will allow a higher load of power transmission.
This is one reason for Louver_tron 313 crown spring with a contact bridge spacing of 2mm being superior to other known crown spring contacts with a contact bridge spacing of 2.5mm or higher.
Contact Bands themselves are much lower in mass than the metal components in a connector. Therfore their thermal capacity is much lower. They depend upon the heat sinking capability of the metal connector components to quickly dissipate heat which will generate under load. This pertains to the choice of the material for the metal connector components as well as the minimum cross section of these components required to handle the load.
Nominal current rating for electrical contacts are usually quoted in conjunction with allowable temperature rise. A connector made of steel components for example and a max. permissible temperature rise of max. 40°C will reach this temperature limit at a lot lower current load than a connector made of copper components.