Buyers who source bare copper flat wire, strip, and foil usually ask the same questions. Which grade fits the job? What thickness and width can the factory really deliver? Will the size stay consistent from one batch to the next?
Junrun is a conductor manufacturer in Zhangjiagang, Jiangsu Province. We run an oxygen-free copper plant and have more than 10 years of focus on conductor products. This guide explains what bare copper flat wire, strip and foil are, which specifications we offer, how to choose a grade and temper, and what to prepare before you ask for a quote. You can also browse our full Bare Copper Series for round wire and related products.
What Is Bare Copper Flat Wire, Strip & Foil?
Bare copper flat wire, strip and foil are flat copper conductors with no insulation and no coating. The surface is plain copper. That makes them easy to wind, bend, weld, stamp and connect in electrical and industrial products.
Our flat products are made from high-purity copper by rolling and drawing. The surface is flat and smooth, the cross-section is uniform, and the corners are rounded. You can order them in soft or hard temper.
Flat wire, strip and foil: how they differ
Industry boundaries vary between factories, so always confirm the exact thickness and width on your drawing. In general:
- Bare copper flat wire: a rectangular conductor with rounded corners, mostly used for coil and transformer winding.
- Copper strip: a wider flat conductor, used for busbars, connectors and stamped parts.
- Copper foil: a very thin flat conductor, used for shielding, battery connections and precision conductive parts.
Bare Copper Flat Wire Specifications: Thickness 0.005mm and Width 0.1-600mm
The table below summarizes the main specifications of our bare copper flat wire, strip and foil. Exact thickness-and-width combinations depend on the product, so please send your drawing for confirmation.
| Parameter | Bare copper flat wire, strip & foil |
| Oxygen-free copper grades | TU0, TU1, TU2 |
| Red copper grades | T1, C101, C102, high-purity electrolytic copper |
| Thickness | From 0.005 mm; tolerance ±0.001 to 0.01 mm |
| Width | 0.1 mm to 600 mm |
| Width tolerance | ±0.02 to 0.1 mm |
| Temper | Soft or hard |
| Edge shape | Flat, with rounded corners |
| Density | 8.89 g/cm³ |
| Resistivity | ≤ 0.017241 Ω·mm²/m |
| Conductivity | ≥ 100% IACS |
| Surface | Bare copper, flat and smooth |
Treat this table as a starting point. If your project needs a tighter tolerance or a special size, tell us early. We will check whether it is workable before you commit.
Oxygen-Free and Red Copper Grades: TU0, TU1, TU2, T1 & C101/C102
Grade selection affects conductivity, forming behavior and cost. We supply two groups of material for flat conductors:
- Oxygen-free copper (TU0, TU1, TU2): very high purity with low oxygen content. A good choice for high-conductivity parts, precision winding and welded joints.
- Red copper (T1, C101, C102) and high-purity electrolytic copper: widely used for general electrical conductors, busbars, connectors and stamped parts.
Grade names follow both Chinese naming (TU, T) and international naming (C101, C102). If your project follows a specific standard, send us the standard and the grade code so we can confirm the right match.
How to choose a grade
- Start from the electrical requirement, such as conductivity and operating temperature.
- Check how the part will be joined. Welded or brazed parts may need higher-purity material.
- Compare grade against budget. Higher purity usually costs more, so avoid over-specifying.
- Ask for a sample in the grade you plan to buy before you place a larger order.
Soft vs Hard Temper Copper Strip: Which One Should You Choose?
Temper describes how hard or soft the copper is after processing. It changes how the strip behaves on your production line, so choose it based on your forming method.
- Soft temper (annealed): easier to bend, wind and form. It suits coil winding, tight bends and parts that need good plasticity.
- Hard temper: keeps its shape and offers higher tensile strength. It suits rigid connections, stamped parts and flat conductors that must resist deformation.
If you are not sure, share the bend radius, the forming or winding method and the end use. We can then suggest a temper and send samples for a trial.
Key Advantages of Bare Copper Flat Wire Over Round Wire
Round copper wire is simple and common. Flat conductors solve problems that round wire cannot handle well:
- Better heat dissipation. The flat structure gives a larger surface area for heat to escape, which helps in compact, high-current designs.
- Efficient use of space. Flat conductors stack neatly, so windings and cable layouts can use space more effectively.
- Good bending and forming. The conductor holds its shape and resists warping during processing.
- Stable conductivity. Pure copper gives low resistance and low energy loss.
- Resistance to temperature and aging. The material performs well across high and low temperatures.
- Small thickness tolerance. This supports precise overlay winding and neat cabling layouts.
If weight is a major concern in your design, you can also compare our Copper-clad aluminum (CCA) flat wire, strip, and foil. CCA has lower conductivity than pure copper, so it fits selected designs only. We can help you compare both options against your requirements.
High Conductivity Copper Strip: ≥100% IACS and Low Resistivity
Conductivity is one of the first things electrical buyers check. Our bare copper flat wire, strip and foil reach a conductivity of 100% IACS or higher, with resistivity of 0.017241 Ω·mm²/m or lower.
In practical terms, low resistivity means less power loss and less heat build-up in the conductor. This matters in transformers, switchgear, battery connections and any design where efficiency and temperature rise are important.
When you compare suppliers, ask how conductivity is verified and in what form the results are provided. You can include this request in your inquiry.
Bare Copper Flat Wire for Transformer and Reactor Windings
Transformers and reactors are among the main uses for bare copper flat wire. Winding makers often buy the bare conductor and apply their own insulation later, so consistent size and surface quality matter.
Our flat wire has rounded corners, a smooth surface and a uniform cross-section. Rounded corners help protect the insulation layer applied in later steps. Soft temper makes winding easier, especially on tight coils.
For winding projects, please send the thickness, width, tolerance, temper and spool or coil requirements. These details let us match the product to your winding process.
Copper Strip for Busbars and High & Low Voltage Switchgear
Copper strip is widely used for busbars and internal connections in high and low voltage switchgear. These parts carry high current, so low resistance and a clean, flat surface are important.
We supply bare copper strip with widths up to 600 mm. For fixed busbar connections, hard temper is common. For parts that need bending during assembly, soft temper may be a better fit. Send us the current rating, the bending requirement and the drawing, and we will suggest a suitable option.
Copper Foil and Strip for Lithium Battery Connectors and New Energy Equipment
New energy equipment needs thin, flat conductors that weld cleanly and keep stable dimensions. Copper foil and strip are used for lithium battery connecting pieces and other new energy components.
For these parts, thickness accuracy and surface condition affect weld quality and production yield. We recommend testing a sample on your own welding or stamping line before bulk purchase. Tell us the grade, thickness, width and joining method, and we can prepare samples for your validation.
Copper Foil for Electromagnetic Shielding and Precision Conductive Parts
Thin copper foil is also used for shielding materials and precision metal conductive parts. In shielding applications, the foil forms a continuous conductive layer around cables or components. In precision parts, it is formed or stamped into small conductive elements.
Consistent thickness and a clean surface help both uses. If you need a specific foil thickness, width or temper, share your drawing and the application. We will confirm what we can supply.
Custom Sizes and Rounded-Corner Flat Wire: What Can We Customize?
Junrun supports OEM and ODM orders. Materials, sizes, structures and packaging can be adjusted to your drawings and specifications. For bare copper flat wire, strip and foil, typical customization items include:
- Copper grade (oxygen-free or red copper)
- Thickness and width, within the ranges above
- Soft or hard temper
- Rounded-corner flat wire structure
- Spool, coil and packing format
- Quantity and delivery schedule
What to include in your inquiry
A complete inquiry saves time on both sides. Please share:
- Grade or standard required
- Thickness, width and tolerance
- Temper (soft or hard)
- Application and processing method
- Estimated quantity and packing preference
- Drawing or sample photo, if available
Tight Thickness Tolerance for Precision Winding and Cabling Layouts
Thickness variation causes real production problems. In winding, small differences add up across many layers and change the coil size. In cabling and stacked assemblies, uneven thickness affects fit and appearance.
Our flat products are made with small thickness tolerance to support precise overlay winding and neat cabling layouts. Our workflow checks material preparation, drawing, surface condition, appearance, dimensional consistency and packaging before delivery.
Tips for choosing a copper flat wire supplier
- Ask for a written tolerance range for thickness and width, not only nominal sizes.
- Request samples and measure them yourself.
- Check that the supplier can repeat the same size across batches.
- Confirm the grade, temper and packing before production starts.
- Tell the supplier early if you need specific test reports or standards, so they can confirm what is available.
How Is Bare Copper Flat Wire Made? Rolling, Drawing and Annealing
Making bare copper flat wire, strip and foil is a controlled, step-by-step process. A simplified flow looks like this:
- Material preparation: high-purity copper is selected according to the grade you order.
- Rolling and drawing: the copper is shaped into the flat cross-section, with the target thickness, width and rounded corners.
- Annealing: soft temper products are annealed to improve flexibility and forming behavior.
- Inspection: dimensions, surface and appearance are checked before packing.
- Packing: products are packed according to your spool, coil and export requirements.
Each step affects the final result. Rolling and drawing control the size and flatness. Annealing controls the temper. Inspection confirms that the product matches your order.
Packaging, MOQ, Samples and Delivery for Copper Flat Wire
We know overseas buyers need clear answers on supply terms. Here is how we usually handle them.
- Packaging: the packing format can be discussed based on product size and end use, including export packing needs.
- MOQ: the minimum order quantity depends on grade, size and temper. Share your target quantity and we will confirm.
- Samples: we support sample preparation so you can test winding, welding, stamping or cabling before a larger order.
- Delivery: production is planned around your order and project schedule. We confirm lead time once the specification and quantity are clear.
Junrun has two production bases, a 15,000 m² factory area and more than 100 sets of equipment. You can learn more about our factory and OEM/ODM support on our About us page.
Frequently Asked Questions About Bare Copper Flat Wire, Strip & Foil
What is the difference between bare copper flat wire, strip and foil?
All three are flat copper conductors without insulation. Flat wire is a rectangular conductor with rounded corners, often used for winding. Strip is wider and used for busbars and connectors. Foil is very thin and used for shielding, battery connections and precision parts. Please confirm exact sizes on your drawing, because the dividing lines vary by factory.
What thickness and width range do you supply?
Our bare copper flat wire, strip and foil start from 0.005 mm thickness, and widths range from 0.1 mm to 600 mm. Tolerances and available combinations depend on the product, so send your drawing for confirmation.
Should I choose soft or hard temper?
Choose soft temper if the conductor must be wound or bent easily. Choose hard temper if it must keep its shape or resist deformation. If you are unsure, tell us your forming method and we will suggest an option and send samples.
Can you customize width, thickness and grade?
Yes. We support OEM and ODM orders. You can customize the copper grade, thickness, width, temper, rounded-corner structure and packaging, based on your drawing and specification.
Can I get samples before placing a bulk order?
Yes. We support sample preparation so you can test the product in your own process. Send your specification and application, and our team will arrange the next steps.
What should I include when I request a quotation?
Include the grade or standard, thickness, width and tolerance, temper, application, estimated quantity and packing preference. A drawing or sample photo helps us respond faster and more accurately.
Conclusion
Choosing the right bare copper flat wire, strip, and foil comes down to a few clear decisions: grade, size and tolerance, temper, and how the product will be processed. A supplier who can match these to your drawing, provide samples and keep dimensions consistent will save you time and cost.
Junrun supports international buyers with custom sizes, soft and hard temper options, OEM/ODM service and sample support. If you are comparing suppliers, send us your specification and application. Our team will review it and reply with product details, a quotation and technical support. Please Contact Sales to start the conversation.