Copper Machining and Fabrication in Janesville, WI — C101, C110, and Tellurium Copper

C101 — oxygen-free high-conductivity copper — is the premium electrical conductor grade, with conductivity at 101 percent IACS and oxygen content below 0.001 percent. The ultra-low oxygen specification prevents hydrogen embrittlement during soldering and brazing operations, making C101 the required grade for applications where the copper will be joined by heat and the joint must maintain both electrical and mechanical integrity. Bus bars, transformer leads, vacuum electronic components, and high-frequency electrical conductors in the industrial equipment sector commonly specify C101 when joint reliability is critical. C110 — electrolytic tough pitch (ETP) copper — is 99.9 percent minimum copper with a conductivity of 100 percent IACS, the most widely available and cost-effective copper grade for general electrical applications. It is not oxygen-free, so hydrogen embrittlement during high-temperature joining is a risk in reducing atmospheres; for applications that will never see reducing-atmosphere brazing or welding, C110 is electrically equivalent to C101 at lower cost. Electrical terminal blocks, current-carrying brackets, heat sink plates, and distribution hardware commonly run in C110 in Janesville's industrial equipment supply chain. Tellurium copper — C14500, commonly called free-machining copper — adds 0.4 to 0.7 percent tellurium to achieve a machinability rating of approximately 90 (compared to 20 for pure C110), while retaining 90 to 93 percent IACS conductivity. For copper parts with complex turned features, cross-holes, and internal threads — electrical connector bodies, valve components, and precision fluid fittings — tellurium copper dramatically reduces cycle time and improves surface finish compared to machining C110. The conductivity trade-off is minor for most applications, and Janesville precision machining shops default to tellurium copper for any copper part with significant machining content.

Copper sheet and plate forming is straightforward compared to stainless — the material's elongation of 35 to 45 percent allows aggressive bending and deep drawing without cracking. Bus bar bending, formed heat sink fins, and terminal mounting brackets in C110 are common outputs from Janesville fabrication shops equipped with press brakes and punch-and-die tooling. Copper's work-hardening rate is lower than stainless, so formed parts retain more ductility after forming and can be re-bent without intermediate anneal on most geometries. Silver brazing is the preferred joining method for copper assembly work in Janesville's electrical and fluid-system sector — BAg-series filler metals at 35 to 72 percent silver content produce joints with 25,000 to 55,000 psi tensile strength and excellent electrical conductivity across the joint. Torch brazing, induction brazing, and furnace brazing are all available regionally. TIG welding of copper requires preheat to 400 to 500 degrees Fahrenheit for sections above 0.060 inch thickness because copper's thermal conductivity pulls heat away from the weld puddle faster than the arc can supply it, preventing fusion without preheat. Tin plating, silver plating, and nickel plating of copper components are the most common surface treatments in Janesville's electrical component supply chain. Tin plating (ASTM B545, 0.0003 to 0.001 inch thickness) prevents surface oxidation and improves solderability for electrical connections. Silver plating (ASTM B700) is specified for high-temperature electrical contacts where tin's melting point of 450 degrees Fahrenheit would be marginal. Nickel underplate beneath tin or silver extends corrosion resistance and prevents diffusion of the plating into the copper substrate over time.