Buyers who source bare copper wire for motors, transformers, electronics or cable production know that a datasheet is only the starting point. You also need a stable diameter, a clean surface, and a supplier who can explain exactly what ships in each batch.
This guide covers what international buyers usually check before they send an inquiry: material grades, sizes, temper, electrical properties, customization, quality control and cost factors. The data follows our product page, so you can compare it directly with your own drawings.
Junrun is a bare copper wire manufacturer in Zhangjiagang, Suzhou, Jiangsu Province, China. We supply T2 copper wire and oxygen-free copper wire in round form from 0.08mm to 4.0mm, plus copper flat wire, strip and foil.
What Is Bare Copper Wire? Definition and Key Features
Bare copper wire is an uninsulated copper conductor. It has no enamel, PVC or other coating, so the wire is 100% copper by volume and by weight. Manufacturers produce it by drawing high-purity copper through dies and annealing it to the required hardness.
Junrun’s wire is a single or multi-strand solid round bare copper wire. The surface is smooth and free of oxidation and burrs. The material is uniform and the conductivity is stable.
Key features buyers look for
- High purity with excellent electrical and thermal conductivity
- Low resistance and low energy loss
- Good toughness and plasticity, so the wire bends and welds easily
- Good resistance to oxidation and corrosion, with high tensile strength
- No insulation layer, which suits direct winding, jumper wires and precision wiring
Because there is no insulation, bare copper wire often serves as a base conductor. Customers use it directly, or they tin, enamel or insulate it in later steps.
T2 Copper vs Oxygen-Free Copper Wire: Which Should You Choose?
Both materials deliver high conductivity. The difference lies in oxygen content, purity level and cost. Junrun supplies oxygen-free copper grades TU0, TU1 and TU2, red copper grades such as T1 and T2, and high-purity electrolytic copper.
When to choose T2 copper wire
T2 copper wire is a practical choice for general electrical wiring, transformer leads, winding and many industrial uses. It offers strong conductivity at a lower material cost, so it suits projects where price and volume matter.
When to choose oxygen-free copper wire
Oxygen-free copper wire has lower oxygen content. Buyers often select it for fine wire, repeated bending, welding or brazing, precision instruments and electronic parts where consistency matters most.
Quick selection guide
- Standard wiring, winding or cost-sensitive orders: start with T2 copper.
- Fine diameters, precision electronics or demanding welding: consider oxygen-free copper.
- Not sure? Send your application, target diameter and conductivity requirement. We will recommend a grade.
Bare Copper Wire Specifications: 0.08mm to 4.0mm
The table below summarizes our standard bare copper wire data. Ultra-fine sizes such as 0.2mm and 0.5mm are available for precision uses. Flat products cover a wide range of widths and thicknesses.
| Parameter | Bare Copper Wire Specification |
| Material | Oxygen-free copper (TU0, TU1, TU2); red copper (T1, T2); high-purity electrolytic copper |
| Product forms | Solid round wire (single or multi-strand); flat wire, strip and foil |
| Round wire diameter | 0.08mm – 4.0mm |
| Diameter tolerance | ±0.005mm |
| Flat wire thickness | From 0.005mm; tolerance ±0.001–0.01mm |
| Flat wire width | 0.1–600mm; tolerance ±0.02–0.1mm |
| Temper | Soft and hard states |
| Density | 8.89 g/cm³ |
| Copper content | 100% by volume and by weight |
| Resistivity | ≤0.017241 Ω·mm²/m |
| Conductivity | ≥100% IACS |
| Surface | Smooth, free of oxidation and burrs |
Final tolerance depends on the diameter and temper you order. Please share your drawing or target size, and we will confirm the exact specification before quotation.
Soft Annealed vs Hard Drawn Bare Copper Wire
Temper changes how the wire behaves in your process. Junrun supplies bare copper wire in both soft and hard states.
Soft annealed copper wire
Annealing softens the copper. Soft annealed wire bends easily, stretches more before it breaks, and welds or solders well. Buyers use it for winding, jumper wires, harness work and fine wiring.
Hard drawn copper wire
Hard drawn wire keeps the strength gained during drawing. It resists stretching and holds its shape. This helps in straight conductors and in applications that need higher tensile strength.
How to choose the temper
- Choose soft wire if it must bend, coil or weld during assembly.
- Choose hard wire if it must hold its shape or carry mechanical load.
- Tell us your forming process, and we will confirm the right temper.
Why Choose Junrun as Your Bare Copper Wire Manufacturer?
Choosing a supplier means more than comparing unit prices. Here is what we offer international buyers.
- Focused manufacturing: We develop and produce copper, copper clad aluminum, copper clad steel and composite conductors. Bare copper wire is one of our six product series.
- Integrated workflow: Drawing, annealing and take-up run in one manufacturing workflow, which supports consistent output.
- Inspection control: We manage batch stability, surface appearance and outgoing inspection.
- Specification matching: Our team matches material, diameter, surface and structure to your application.
- One source for related products: Besides bare copper, we supply tinned wire, enameled wire, CCA wire and PV solar ribbon.
If weight matters in your project, review our Copper-Clad Aluminum Series. It combines a copper outer layer with a lightweight aluminum core.
Electrical Properties: Conductivity ≥100% IACS and Low Resistivity
Electrical performance is the main reason buyers choose copper. Our product data lists resistivity of ≤0.017241 Ω·mm²/m and conductivity of ≥100% IACS.
IACS stands for International Annealed Copper Standard. A value of 100% IACS is the reference level for pure annealed copper, equal to 0.017241 Ω·mm²/m at 20°C. Lower resistivity means less heat and less power loss in the conductor.
What to check before you order
- Confirm the test temperature used for resistivity values.
- Ask whether the value applies to soft or hard wire. Hard drawn wire can show slightly lower conductivity than annealed wire.
- Request test data on your sample before you place a bulk order.
- Consider thermal conductivity if your part must dissipate heat.
Round Bare Copper Wire and Flat Copper Strip Options
Round bare copper wire
Round wire is the standard choice for winding, wiring and cable conductors. Diameters range from 0.08mm to 4.0mm, with a diameter tolerance of ±0.005mm.
Flat copper wire, strip and foil
Copper flat wire, strip and foil is made from high-purity copper by rolling and drawing. It has rounded corners, a uniform cross-section and high dimensional accuracy. You can order it in soft or hard state.
The flat shape gives a larger surface area for heat dissipation, and it bends and forms well. Typical uses include transformers, reactors, switchgear, busbars, motor windings, new energy equipment and lithium battery connecting pieces.
Need a coated surface?
If your process needs better solderability or corrosion resistance, ask about tinned bare copper wire. It uses bare round copper wire as the base, with a bright, uniform pure tin layer.
Common Applications of Bare Copper Wire
Buyers use bare copper wire wherever a clean, conductive and formable base conductor is needed. Common applications include:
- Electronics: circuit board wires, jumper wires and internal wiring of electrical appliances
- Electrical equipment: motor winding, transformers and general industrial equipment
- Precision instruments: precision wiring that needs stable conductivity
- Communication: communication cable conductors and network cabling
- New energy: conductor connections in energy equipment
- Workshop and DIY winding: coils, small motors and custom wound parts
If your application is not on this list, send us the details. We will check whether our wire fits your process.
Bare Copper Wire for Motor Winding, Transformers and Electronics
Motor winding and transformers
Motor and transformer makers need wire that winds evenly and keeps stable resistance. Soft annealed bare copper wire forms tight coils. Copper flat wire suits layered winding because its thickness tolerance is small. If you need insulated winding wire, see our Enameled Wire Product Series.
Electronics and precision instruments
Fine diameters such as 0.2mm and 0.5mm suit circuit board leads, jumper wires and precision wiring. A tight diameter tolerance of ±0.005mm supports consistent assembly.
Communication and network cable
Communication cable conductors and data cable projects need stable conductivity and a clean surface. Tell us your cable structure, and we will recommend the grade, diameter and temper.
Custom Sizes, Packaging and Spool Options
Many buyers need more than a catalog size. Junrun offers custom size, surface and packaging support for winding, harness and downstream processing.
To speed up your quotation, please send the following details:
- Material grade (T2, TU1, TU2 or other)
- Diameter, or flat wire width and thickness, with target tolerance
- Temper: soft or hard
- Required length or weight per spool or coil
- Preferred packaging and any export packing needs
- Drawing, technical sheet or application description
We will confirm what we can supply and suggest alternatives if a requirement is difficult to produce.
Quality Control and Testing Standards
Stable quality starts with controlled drawing and annealing, and it continues through final inspection. At Junrun, we manage batch stability, surface appearance and outgoing inspection. Our wire should have a smooth surface without oxidation or burrs, and the diameter should stay within the agreed tolerance.
Every market asks for different documents. If you need a specific standard, such as ASTM, IEC or GB/T, please tell us before quotation. We will confirm the test items and reports we can provide.
How to verify a bare copper wire supplier
- Ask for diameter, tolerance, resistivity or conductivity, and surface data.
- Request a sample and test it in your own winding, welding or soldering process.
- Check that the product description, test data and packing list match.
- Confirm what documents come with each shipment.
MOQ, Lead Time and Free Sample Support
Minimum order quantity and lead time depend on the grade, diameter, temper and packaging. Fine wire and custom sizes may need different planning from standard sizes. We confirm both in the quotation, so please share your expected quantity and target delivery date.
We also support sampling. You can request samples for winding, welding, soldering or other process validation. Sample terms depend on the specification and quantity, so please ask our team for details.
For export orders, confirm shipping terms such as FOB or CIF during quotation. Contact Us to start the discussion.
Bare Copper Wire Price: What Affects the Cost?
Copper is the main cost driver, and its market price changes often. For that reason, we quote based on current market conditions and your exact specification. These factors affect the final price:
- Copper price: the daily market price of copper
- Material grade: oxygen-free copper usually costs more than T2 copper
- Diameter: finer wire needs more drawing steps and tighter control
- Temper and tolerance: annealing and tight tolerance add processing
- Packaging: spool type, net weight and export packing
- Order quantity and shipping terms
To compare quotes fairly, give every supplier the same specification and quantity.
Frequently Asked Questions About Bare Copper Wire
What is bare copper wire used for?
Bare copper wire is used for motor and transformer winding, circuit board wiring, jumper wires, electrical equipment, precision instruments and communication cable conductors. Many customers also use it as a base wire for tinning or enameling.
What sizes of bare copper wire does Junrun supply?
Round wire diameters range from 0.08mm to 4.0mm, including ultra-fine sizes such as 0.2mm and 0.5mm. Flat wire, strip and foil are available in widths from 0.1mm to 600mm.
Should I choose T2 copper or oxygen-free copper?
Choose T2 copper wire for general wiring and winding where cost matters. Choose oxygen-free copper wire for fine wire, precision electronics or demanding welding. Our team can advise based on your application.
What is the difference between soft and hard bare copper wire?
Soft wire is annealed, so it bends and welds easily. Hard wire keeps its drawn strength and holds its shape. The right choice depends on your forming and assembly process.
Can Junrun customize bare copper wire?
Yes. We support custom size, surface and packaging. Send us your diameter, tolerance, temper, quantity and application, and we will confirm what we can supply.
What information do I need to request a quotation?
Please send the material grade, diameter or flat wire dimensions, temper, quantity, packaging needs and application. A drawing or technical sheet helps us respond faster.
Request a Quote for Bare Copper Wire Today
Reliable bare copper wire comes from clear specifications, controlled processing and open communication. Whether you need T2 or oxygen-free copper, round wire or flat strip, standard or custom sizes, Junrun can support your project.
Share your specification, application and target quantity, and our team will help with material selection, samples and quotation. Contact Us today to discuss your bare copper wire requirements.
| Junrun – Contact Information Email: sonia@junrun-supercon.com WhatsApp / Phone: +86 198 5123 5350 Address: No. 7, Xionghua Road, Tangqiao Town, Zhangjiagang City, Suzhou City, Jiangsu Province, China Website: www.ccam-wire.com |