Welding or brazing C10100 Oxygen-Free Electronic copper is notoriously difficult, not because the metal is "unweldable," but because its extreme purity is its own worst enemy. With a thermal conductivity of ~391 W/m-K, the heat vanishes as fast as you can apply it.
If your process isn't calibrated for 99.99% purity, you risk turning an expensive piece of OFE copper into a contaminated, brittle mess. Here is how to maintain 101% IACS conductivity and vacuum integrity during the joining process.
Why is C10100 the preferred grade for high-vacuum brazing?
The main reason engineers insist on C10100 for brazed assemblies is the < 5 ppm oxygen content. In standard copper, oxygen reacts with hydrogen in the brazing atmosphere to form steam (H2O), causing "Hydrogen Embrittlement."
Because our C10100 Seamless Tube & Pipe is certified under ASTM B170 Grade 1, it can withstand prolonged heating in reducing atmospheres without internal cracking. This is critical for manufacturing leak-free cooling manifolds and MRI components.
What are the best welding methods for C10100 copper?
Due to the rapid heat dissipation of OFE copper, traditional welding requires specialized approaches:
Gas Tungsten Arc Welding (TIG/GTAW): The most common choice. Use Helium or Helium-Argon mixes as a shielding gas. Helium provides a hotter arc than pure Argon, which is necessary to overcome the thermal "heatsink" effect of large C10100 plates.
Electron Beam Welding (EBW): The gold standard for vacuum electronics. Since EBW happens in a vacuum, it preserves the 99.99% purity of the base metal and creates narrow, deep-penetrating welds with zero oxidation.
Laser Welding: Increasingly used for C10100 Bare Wire and thin foils, though back-reflection can be an issue due to copper's high reflectivity.
Which filler metals should you use to maintain 101% IACS?
When brazing, the filler metal is the "weak link." To maintain high electrical performance in C10100 Round, Square & Flat Bar applications, you must choose carefully:
Silver-Based Fillers (B-Ag series): High-silver content alloys offer the best balance of flow and conductivity.
Avoid Phosphorus: Never use self-fluxing Copper-Phosphorus (Cu-P) fillers for vacuum electronics. The phosphorus can outgas and contaminate the vacuum chamber, ruining the "Electronic Grade" status of your C10100.
How do you prevent contamination during the C10100 joining process?
Contamination is the silent killer of conductivity. Even fingerprints can introduce enough carbon to cause surface defects during heating.
Pre-Weld Cleaning: Use an abrasive-free degreaser followed by a brief etch in a 10-20% Nitric Acid (HNO3) solution. Rinse with deionized water.
Atmosphere Control: If you are not using a vacuum furnace, ensure your shielding gas has a purity of 99.999% to prevent surface oxidation of the C10100 Plate, Sheet.
Does C10100 require preheating before welding?
Yes. For sections thicker than 3mm, preheating to 200°C - 400°C is often necessary. Without preheating, the "cold start" of the weld will lack fusion because the C10100 base metal sucks the heat away before the puddle can form.
At GNEE METAL, we provide Custom CNC Machined Parts that are pre-beveled and cleaned for immediate welding, saving your workshop hours of prep time.
For more details on how these metallurgical properties are verified, refer to our guide on ASTM F68 and ASTM B170 Grade 1 specifications.
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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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