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→5.1.2 Pure Copper
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:Softening of Cu-ETP after annealing for 3hrs after 25% cold workingtab5.2"/> 5.2)''. <xr id="tab:tab5.3"/> Tables 5.3. and <xr id="tab:tab5.4"/> 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).