Canted coil spring contacts: ten years of manufacturing

Canted coil spring contacts, also called finger springs, are produced on computer-controlled spring machines and demand precise welding. The wire is formed into a circular spring whose coils are elliptical and inclined. When the ring is compressed, each coil deforms independently, and whatever part of the coil deforms, the spring as a whole reacts so that the load is consistent at every contact point. For connectors, the two ends of the spring are welded together to form a complete ring, and the ring is placed in a recess in the receptacle or plug design to meet the insertion and extraction force required for each standard coil size.

How the connection is held

When the convex groove of the mating part is inserted into the recess, the canted coil spring deforms under continuous spring stress and offers resistance until the coil pairs with the groove. The coil load and groove design then generate a continuous spring stress, so that a corresponding pull-out force is required to separate the two components. A radial canted coil spring therefore plays two key roles in a miniature connection: it snaps the connection in place and reduces the number of components in the system.

Manufacturing capability

Dongguan Spring-in-Spring Electronics Co., Ltd. (SiS) was established in October 2011 and specializes in the design, testing and manufacture of elastic conductive electronic components. The company moved to Chang'an Town, Dongguan in May 2018 and operates a CNC lathe workshop, a finger-spring workshop, an assembly workshop and a laboratory.

In response to the connector industry's demand for high-current connectors, SiS developed a bidirectional coil spring finger (SiS) and a single-turn spring finger that form multiple columnar contact points, up to 300 or more. The contacts meet a service life of more than 100,000 cycles, with a current density and temperature rise close to those of a transmission cable and an insertion force of about 10 N.

Applications

The contacts are used in PCB connectors (board-to-board USC and board-to-wire), cylindrical quick-connect self-locking connectors with plastic and metal shells, and heavy-load male and female connectors. They also serve electric vehicle chargers and high-voltage power battery pack connectors, and are used in advanced high-current energy collectors, energy storage and electrical equipment such as electric vehicles, charging base stations, wind generators, power supplies, high-speed rail and heavy trucks. The company holds a number of national patents and its products have passed international standard testing.