Best thermal conductor. Best electrical conductor. Machinable.

Copper is soft and ductile (HRB 40 vs 95 for brass) with low strength (69 MPa yield). Chips are long and stringy, gumming up tools. Work hardens rapidly, so interrupted cuts or rubbing tools immediately harden the surface and destroy edges. Best technique: sharp positive-rake tools, aggressive feed (not dwelling), flood coolant, and avoiding re-cutting chips. For high-volume copper parts, specify C145 tellurium copper — 2–3× the machinability at 95%+ of the conductivity.

Pure copper cannot be precipitation hardened — its strength comes only from cold work. Alloyed coppers (CuCrZr, beryllium copper) are precipitation-hardenable, achieving 450–1,250 MPa yield after solution treatment and aging. For strength-requiring applications, specify an alloy rather than pure copper.

Copper has 1.7× aluminum's thermal conductivity (391 vs 237 W/m·K), but 3× the density and 3× the cost. For equal thermal performance by weight, aluminum wins decisively — that's why almost all production heat sinks are aluminum. Copper heat sinks are used when: (1) space is highly constrained and weight isn't (server CPUs), (2) heat flux is extreme (rocket engines, fusion reactors), (3) combined with aluminum in hybrid designs (copper base + aluminum fins).

Tin and nickel plating performed in-house. Silver and gold plating through vetted specialty partners. For aerospace-grade plating (gold on RF connectors, palladium barriers), we work with US-origin qualified plating shops on specific projects. All platings documented on the certificate of conformance.

Electrolytic Tough Pitch (ETP, C110) contains ~0.04% oxygen from the refining process. Oxygen-Free Electronic (OFE, C101) is remelted in reducing atmosphere to < 0.001% oxygen. OFE eliminates hydrogen embrittlement in brazing and welding, slightly improves conductivity, and is preferred for vacuum, nuclear, and semiconductor applications. For general electrical and thermal, ETP is adequate and cheaper.