Copper Alloy Knowledge and FAQ銅合金技術知識與常見問答

C1020 is oxygen-free copper (OF), with at least 99.96% copper. C1100 is tough pitch copper (ETP), with at least 99.90% copper.

Both are copper-zinc alloys. C2600 has 68.5–71.5% copper. C2680 has 64.0–68.0% copper. Under CNS 11073, the required tensile strength is the same for both. C2680 is often used for deep-drawn parts such as snap fasteners (copper buttons) and camera parts. C2600 is used for items such as terminals and connectors.

Both are phosphor bronze. C5191 has 5.5–7.0% tin (CNS 9503). C5210 has 7.0–9.0% tin (CNS 3114, for springs). In full hard (H) temper, the required tensile strength is 590–685 N/mm² for C5191 and 590–705 N/mm² for C5210. C5210 also has a required spring limit value (the highest stress a spring can take and still return to its original shape).

C7521 and C7701 are copper-nickel-zinc alloys. They contain 16.5–19.5% nickel. Copper is 62.0–66.0% in C7521 and 54.0–58.0% in C7701. The name "nickel silver" (also called "German silver") comes from its silver-white color. They do not contain silver. They are used for coins, medical devices, musical instruments, and electrical materials.

CNS 3114 (for springs) covers C1720 beryllium copper, C5210 phosphor bronze, and C7701 nickel silver. It also sets spring limit values (the highest stress a spring can take and still return to its original shape). The best choice depends on your needs for strength, conductivity, and forming.

We usually carry C1020, C1100, C1720, C2680, C5191, and C7521. If the grade you need is not listed, please contact us.

C1100 matches UNS C11000 and EN Cu-ETP (CW004A). C1020 matches UNS C10200 and EN Cu-OF (CW008A). C2680 matches UNS C26800 and EN CuZn33 (CW506L). C5191 matches UNS C51900 and EN CuSn6 (CW452K). C1940 matches UNS C19400 and EN CuFe2P (CW107C). These are close equivalents, not exact matches. If you must meet a specific standard, please use the grade that standard names.

O means fully recrystallized or annealed. It has the lowest tensile strength. 1/4H (quarter hard), 1/2H (half hard), 3/4H (three-quarter hard), and H (full hard) are made harder by cold working, and strength goes up at each step. EH (Extra Hard), SH (Spring Hard), and ESH (Extra Spring Hard) are harder tempers with even higher strength.

A harder temper means higher strength. If you need to bend the metal, a harder temper needs a larger inside bend radius.

This follows CNS 11073 (the Taiwan national standard). For C1020 and C1100 in annealed (O) temper, thickness over 0.50 mm, conductivity is at least 100% IACS (International Annealed Copper Standard). For quarter hard (1/4H) and half hard (1/2H), thickness up to 2.0 mm, it is at least 97%. For full hard (H), thickness up to 2.0 mm, it is at least 96%.

IACS stands for International Annealed Copper Standard. It is a standard scale for how well a metal carries electricity. In 1913, the International Electrotechnical Commission (IEC) set the conductivity of standard annealed copper at 20°C as 100% IACS. That value is 58.0 MS/m (a resistivity of about 1.7241 µΩ·cm). The conductivity of other metals and alloys is compared with it and shown as a percentage. A higher number means better conductivity. For example, 50% IACS means the metal carries electricity half as well as standard annealed copper.

The 100% IACS mark was set using the standard annealed copper of 1913. Since then, copper refining has improved. Commercial pure copper is now purer and has fewer impurities, so its conductivity is slightly higher than that old baseline. For example, oxygen-free copper can often reach about 101% IACS. So IACS is a reference point, not an upper limit on conductivity.

Some copper alloys sold by Sursun Metals may contain lead. Our SGS test reports show that our copper alloys meet the RoHS (Restriction of Hazardous Substances) limit for lead. For exact composition, please see the mill test certificate (MTC) or a third-party test report. Under CNS, lead is 0.05% or less for C2600 and C2680. It is 0.03% or less for C1940, C7521, and C7701. It is 0.02% or less for C5191 and C5210. CNS sets no upper lead limit for C1020, C1100, C1921, and C1720. We do not add lead on purpose to C1921 and C1940.

Copper surfaces may oxidize and turn dark when they touch oxygen, moisture, sulfur-containing gases, or sweat from hands. A green patina (verdigris) may even form. We suggest you store copper in a dry place, avoid touching it with bare hands, and use anti-tarnish paper or sealed packaging.