Copper Machining and Fabrication in Stockton, CA — C101, C110, and Tellurium Copper

C101 (Oxygen-Free Electronic Copper, OFE) carries 99.99% Cu minimum with oxygen content below 5 ppm, yielding electrical conductivity at 101% IACS — the reference standard for conductivity measurement. Its oxygen-free chemistry prevents hydrogen embrittlement during high-temperature brazing and annealing operations, making it the required grade for electronics and vacuum applications. In Stockton-area applications, C101 appears in precision bus bar components for power conversion equipment, high-frequency coils for induction heating systems used in food processing, and specialty electrical connectors for solar and storage system integration. C110 (Electrolytic Tough Pitch Copper) at 99.9% Cu minimum and 0.02-0.04% oxygen is the volume grade for electrical conductors and heat transfer applications. Its conductivity at 97% IACS is marginally below C101 but adequate for virtually all power distribution applications, and its availability in rod, plate, and sheet from regional distributors makes it the practical first-choice specification for bus bars, heat exchanger tubes, and grounding systems. C110 is the grade running through Stockton's utility infrastructure and equipment manufacturing supply chains. Tellurium copper (C145, Cu-0.5%Te) trades a small conductivity penalty — 93% IACS — for a machining rating of 90% (versus approximately 20% for C110), making it the standard choice for high-volume turned parts: electrical contacts, terminals, connectors, and any precision-machined component where C110's gumminess creates surface finish and tolerance holding problems. The tellurium addition breaks chips cleanly and allows the cutting speeds and feeds typical of brass on CNC turning centers. Stockton shops running tellurium copper on Swiss-type and standard CNC lathes achieve tolerances of ±0.0005" on connector contact diameters routinely.

Copper's thermal conductivity at 231 BTU/(hr·ft·°F) — roughly four times that of steel and eight times that of stainless — makes it irreplaceable in heat exchanger applications where compact size or rapid thermal response is the design driver. In Stockton's food processing sector, copper appears in jacketed vessel heating coils, pasteurization heat exchanger tube sheets, and induction heating susceptors. OFHC C101 copper is specified where the component will be brazed — its oxygen-free chemistry prevents internal steam blisters that form when oxygen-bearing coppers are heated to brazing temperature in hydrogen-containing atmospheres. Cooling plates and cold plates for power electronics — increasingly common in solar inverters, motor drives, and battery management systems assembled in the Stockton industrial corridor — are machined from C110 plate with deep drilled or broached internal channels. The thermal conductivity advantage over aluminum (231 versus 137 BTU/(hr·ft·°F)) justifies copper's higher cost and weight in applications where the cooling plate footprint is constrained. Shops running these parts use standard carbide tooling at reduced speeds relative to aluminum — 250-350 SFM on roughing versus 1000+ for aluminum — with flood coolant to manage heat buildup in the workpiece. Agricultural refrigeration and cold storage facilities in the Stockton area — which store everything from tomatoes and asparagus to dairy products — use copper refrigerant piping and evaporator coils as the standard system design. Fabrication shops serve this segment with custom copper tube assemblies, elbows, and manifold components brazed with BCuP-5 (phosphor-silver) filler for ACR (Air Conditioning and Refrigeration) service.