Spring finger contacts: how they work and what they do

A spring finger, also called a spring contact, finger spring or contact spring, is a type of canted coil spring. It transmits strong current in a small space and can also be used as a purely mechanical connection. There are no restrictions on its use: it suits both static and dynamic connections in medium- and high-voltage environments. The size of the spring and the number of independent coil turns make it adaptable to a wide range of electrical contact designs, and to electrical or EMI shielding applications where maximum current-carrying capacity and a large number of contact points are required.

How the spring finger works

Each coil independently compensates for contact and surface variations, which allows wider tolerances between mating parts. Multiple contact points increase conductivity, and because the operating temperature stays relatively low, service life is extended.

Typical applications

Spring finger technology is used in power contact applications across medical electronics and medical devices, aerospace and defense, energy and automotive. Common applications include high- and medium-voltage switchgear, mechatronic equipment, high-voltage electric-chain end parts, solid-insulated poles, high-current connectors, fuse connectors and busbar connectors.

Advantages of spring finger contacts

The spring finger has a simple structure, small size, low material use and low cost. It satisfies the space and size requirements of compact equipment designs, and the small number of components simplifies the design of the connecting device. Contact pressure at each point is modest, which gives the part good wear resistance.

Multi-point contact provides a high degree of contact concentration with almost loss-free contact, ensuring large current-carrying capacity, good conductivity and high electrical and thermal stability. The unique structure provides a wide working range, permits generous tolerances on the contact surfaces, and adapts well to machining and assembly errors, which makes it well suited to large-scale production.