The OFE-OK® production follows the same technology as the OF-OK® production, but only the highest quality ingots are selected for this grade, and with this exceptionally strict quality control. Thus, absolutely quality material with a higher electrical conductivity and a very low level of impurities is guaranteed. The total content of impurities (including Ag) is not less than 40 ppm (0.0040%). To ensure the full resistance to hydrogen embrittlement, the maximum oxygen content in OFE-OK® is limited to 3 ppm (0.0003%). Usually the oxygen content in OFE-OK® is much lower. The content of chemical elements of volatiles in a vacuum at high temperatures, i.e. impurities harmful when used in electronic industry, very low.

CHEMICAL COMPOSITION, %

Cu	P	S	Zn	Cd	O	Hg	Bi	Pb	Se
99.99	0.0001	0.005	0.0001	0.0001	0.0002	0.0001	0.0001	0.0002	0.0001

Weldability of copper

High thermal and electrical conductivity of copper makes it difficult to weld (point and roller). This is especially true for massive products. Fine parts can be welded with tungsten electrodes. Parts with a thickness of more than 2 mm can be welded with a neutral acetylene-oxygen flame. A reliable method of joining copper products is soldering with soft and hard solders.

Mechanical Properties

	Soft Condition	Semi-Solid Condition	Solid Condition
Hardness According to Vickers, HV	35 – 65	70 – 95	85 – 115
The tensile strength, MPa	200 – 220	250 – 350	260 – 400
0.2% Yield strength, MPa	35-65	180-280	220-380
Elongation, %	40	12	5