C10100 Oxygen-Free Electronic (OFE) copper is a high-purity, soft metal. Its metallurgical structure-99.99% purity and Max 5ppm oxygen-makes it highly ductile but also prone to "smearing" during secondary operations. Achieving the correct surface finish isn't about looks; it controls electrical contact resistance, plating adhesion, and the performance of high-frequency conductors. A poor finish on a 101% IACS bar can lead to localized hotspots that negate the thermal benefits of the alloy.
What are the standard surface finishes for C10100 products?
Most procurement managers assume a "bright" surface equals high quality. In reality, the mechanical state of the surface depends on whether it was cold-rolled, drawn, or secondary-processed. Below are the functional finishes we provide for C10100 Oxygen-Free Electronic copper.
1. Mill Finish (As-Drawn/As-Rolled)
This is the standard state for C10100 Round, Square & Flat Bar. The Ra typically ranges from 1.6µm to 3.2µm. While acceptable for general grounding or busbars, a mill finish often has microscopic scale or drawing oils that must be removed before high-performance use.
2. Machined Finish (CNC)
When we produce Custom CNC Machined C10100 Parts, the Ra is typically 0.8µm to 1.6µm. Because C10100 is "gummy," standard tool speeds can cause a "cloudy" finish. High-rake, polished tools are required to achieve a clean cut without the "smearing" that can hide sub-surface defects-a common issue mentioned in our guide on avoiding C10100 sourcing traps.
3. Electropolished Finish
This chemical process removes the top layer of the copper, eliminating the "disturbed" layer caused by mechanical cutting. It results in a surface with Ra 0.1µm to 0.4µm. It is the preferred finish for components where the lowest possible surface resistance is required for high-frequency signal transmission.
C10100 Surface Finish Reference
| Finish Type | Ra Value (µm) | Ra Value (µin) | Typical Use Case |
| Standard Mill | 1.6 - 3.2 | 63 - 125 | Electrical Busbars |
| Machined (Fine) | 0.8 - 1.6 | 32 - 63 | Heat Sinks / Electrodes |
| Ground / Lapped | 0.4 - 0.8 | 16 - 32 | High-Pressure Seals |
| Electropolished | 0.1 - 0.4 | 4 - 16 | RF Cavities / Accelerators |
Why does the surface finish affect plating and welding?
The oxide layer on C10100 is much thinner than on ETP copper because of the 5ppm oxygen limit. However, a rough surface increases the "actual surface area," which allows oxides to form faster in ambient conditions.
If you are welding thick C10100 Plate and Sheet, a smoother surface allows for better shielding gas coverage and more consistent laser absorption. For plating (Silver, Tin, or Gold), a surface that has been "smeared" by poor machining will trap plating salts, leading to blistering or "measling" of the finish over time. This also complicates weight-based quality checks, as detailed in our C10100 bar weight calculator.
Cleaning Protocols for C10100 Surfaces
| Method | Contaminant Removed | Resulting Surface |
| Solvent Degreasing | Machining oils / Greases | Chemically clean, original Ra |
| Citric Acid Pickling | Surface oxides (CuO) | Bright, active copper |
| Bright Dipping | Heavy scale / Discoloration | Levelled surface, highly reflective |
| Mechanical Buffing | Scratches / Pits | Smooth, but risks embedding abrasives |
FAQ
1. Does a mirror finish improve electrical conductivity?
It does not change the 101% IACS bulk conductivity, but it reduces the AC resistance in high-frequency applications where current flows on the "skin" of the material. A smoother surface reduces the path length for electron flow.
2. Why does my C10100 look "dull" after CNC machining?
This is usually caused by "Built-Up Edge" (BUE) on the cutting tool. Because C10100 is soft, the copper sticks to the tool and "tears" the surface instead of cutting it. Polished carbide or PCD tools are necessary to keep the Ra low.
3. How do you measure the surface of 10100 Seamless Tubes?
We use profilometers to measure the Outside Diameter (OD). For the Inside Diameter (ID) of small tubes, we use borescope inspection and comparison standards to ensure the draw-bench lubricants haven't caused surface pitting.
4. What is the best way to prevent oxidation during shipping?
C10100 is highly reactive. We use VCI (Volatile Corrosion Inhibitor) paper and nitrogen-purged vacuum packaging to ensure the surface remains bright and oxide-free until it reaches your facility.
5. Can I achieve an Ra 0.4µm finish with mechanical grinding?
Yes, but you risk embedding abrasive particles (silicon carbide or aluminum oxide) into the soft copper. For high-purity electronics, we recommend chemical polishing or electropolishing over mechanical grinding to avoid contamination.
6. Does surface finish affect brazing?
A slightly roughened surface (Ra 0.8 to 1.2µm) can actually help the "wetting" of the braze alloy through capillary action. However, the surface must be 100% free of oxides and oils, or the joint will fail.
Discuss Your Project Requirements
GNEE METAL Product Range
| Product Type | Shapes Available | Common Grades | Diameter/Thickness Range | Length/Width Range | Applications |
|---|---|---|---|---|---|
| Copper Tubes | Round, Square, Rectangular, Coiled | C10100, C10200, C11000, C12200, C12000 | OD: 0.5mm - 300mm Wall: 0.1mm - 20mm | Up to 6000mm or custom | HVAC, Plumbing, Heat Exchangers, Refrigeration, Hydraulic Lines |
| Copper Plates & Sheets | Flat Sheets, Perforated, Embossed, Tread Plate | C10100, C11000, C12200, C23000, C26000 | Thickness: 0.1mm - 200mm | Width: Up to 2500mm Length: Up to 6000mm | Electrical Busbars, Roofing, Cladding, Gaskets, Transformers |
| Copper Bars & Rods | Round Bar, Square Bar, Hexagonal Bar, Flat Bar | C10100, C11000, C14500, C17200, C18200 | Diameter: 1mm - 300mm | Length: 1000mm - 4000mm | Machined Components, Electrical Contacts, Busbars, Fasteners |
| Copper Wires | Round Wire, Flat Wire, Square Wire, Stranded, Braided | C11000, C11600, C17200, C17510 | Diameter: 0.05mm - 12mm | Coil weights: 1kg - 500kg | Electrical Wiring, Cables, Springs, Mesh, Welding Wire |
| Copper Strips & Coils | Thin Strip, Foil, Slit Coil, Profile Strip | C11000, C12200, C19400, C26000, C26800 | Thickness: 0.03mm - 5mm | Width: 2mm - 1000mm Coil ID: 300mm - 600mm | Transformers, Radiators, Shielding, Terminals, Connectors |
About Our Factory
We operate a full range of production lines including extrusion presses, cold drawing benches, high-speed rolling mills, slitting lines, and precision CNC machining centers, enabling us to produce copper tubes, plates, bars, wires, and strips entirely in-house. For quality assurance, we maintain a dedicated inspection laboratory equipped with spectral analyzers, universal testing machines, hardness testers, surface roughness testers, and optical measuring instruments. Every batch is tested for chemical composition, mechanical properties, and dimensional accuracy before shipment. Our production capacity reaches 500+ tons per month, and we hold ISO 9001:2015 certification with full traceability from raw material to finished product. Whether you need standard mill stock or custom-processed components, we deliver precision copper products with short lead times and complete material certification.
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