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→High Cu Content Copper Alloys
The purity of technically pure and un-alloyed copper used for electrical applications depends on the type used and ranges between > 99.90 and 99.95
wt%. The copper types are designated mainly by their oxygen content as oxygen containing, oxygen-free, and de-oxidized with phosphorus as
described in DIN EN 1652 (<xr id="tab:MaterialDesignations"/> and <xr id="tab:Composition of Some Pure Copper Types"/><!--5.2-->). (<xr id="tab:Physical Properties of Some Copper Types"/><!--Tables 5.3.--> and <xr id="tab:Mechanical Properties of Some Copper Types"/><!--5.4-->) show the physical and mechanical properties of these copper materials. According to these, Cu-ETP, Cu-OFE and Cu-HCP are the types of copper for which minimum values for the electrical conductivity are guaranteed.
Cu-ETP is less suitable for welding or for brazing in reducing atmosphere because of the oxygen content (danger of hydrogen embrittlement).
<figure id="fig:Influence of small additions on the electrical conductivity of copper">
[[File:Influence of small additions on the electrical conductivity of copper.jpg|right|thumb|Figure 4: Influence of small additions on the electrical conductivity of copper]]
</figure>
CuNi1Co1Si also belongs into this family and has properties similar to the low alloyed CuBe materials.
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<figtable id="tab:Physical Properties of Selected High Cu Content Copper Alloys">
If current carrying capability is the key requirement, mechanical strength may have to be sacrificed as for example in carrier parts for stationary contacts. In this case, depending on the current level, pure copper or low alloyed copper materials such as CuSn0.15, or for economic reasons CuZn30, may be suitable.
For spring contact components, the interdependent relations between electrical conductivity and fatigue strength, or electrical conductivity and relaxation behavior are of main importance. The first case is critical for higher load relay springs. CuAg2 plays an important role for these applications. The latter is critical for components that are exposed to continuing high mechanical stresses like for example in connectors. The spring force must stay close to constant over the expected life time of the parts, even at elevated temperatures from the environment or current carrying. In this case, the relaxation behavior of the copper materials, which may cause a decrease in spring force over time, must be considered. Besides this, easy forming during manufacturing must be possible; this means, that bending operations can also be performed at high mechanical strength values.
The increasing requirements on spring components in connectors, especially for use in automotive applications, such as higher surrounding temperatures, increased reliability and the trend towards miniaturization led to a change of materials from traditionally CuZn30 and CuSn4 to CuNiSi alloys, for example. These CuNiSi alloys and the newer heavy duty copper alloys like CuNi1Co1, are significantly improved with regards to mechanical strength, relaxation behavior and electrical conductivity.
==<!--5.3-->Triple-Layer Carrier Materials==
Manufacturing of triple-layer carrier materials is usually performed by cold rollcladding. The three materials cover each other completely. The advantage of this composite material group is, that the different mechanical and physical properties of the individual components can be combined with each other.
Depending on the intended application, the following layer systems are utilized:
