High-precision slit copper foil is a key conductive material in transformer winding manufacturing. Compared to ordinary copper foil, high-precision slit copper foil has stricter thickness tolerances, smoother edge quality, and more stable electrical performance, meeting the stringent requirements of high-voltage and ultra-high-voltage transformers for winding materials.
I. Technical Advantages of High-Precision Slit Copper Foil
1.1 What is High-Precision Slit Copper Foil?
High-precision slit copper foil refers to copper foil products processed into specific width dimensions through a precision slit process. Its core characteristics are small width tolerance, good edge quality, and excellent thickness uniformity.
The width tolerance of ordinary slits is generally around ±0.3mm, while high-precision slits can achieve within ±0.05mm. This difference in precision is significant on automated winding lines, directly affecting winding quality and production efficiency.
1.2 Core Differences from Ordinary Copper Foil
Stricter Thickness Tolerances: Ordinary copper foil has a thickness tolerance of ±0.02mm, while high-precision slit copper foil can achieve ±0.01mm or even ±0.005mm.
Smoother Edge Quality: High-precision slitting uses professional slitting equipment, resulting in burr-free and smooth edges, avoiding damage to the insulation layer during winding.
More Stable Electrical Performance: Uniform thickness and smooth edges result in more even current distribution and a lower risk of partial discharge.
Higher Material Utilization: High precision reduces overlap loss and improves material utilization.
1.3 Main Application Areas
- High Voltage Transformer (110kV and above)
- Ultra-High Voltage Transformer (500kV and above)
- Converter Transformer
- Electric Furnace Transformer
- Special Transformer
- High Frequency Transformer
II. Detailed Specifications
2.1 Copper Foil Substrate Requirements
Material: Pure copper C11000 (red copper), copper content ≥ 99.90%
Conductivity: Annealed state IACS ≥ 98%
Thickness Range: 0.05-3.0mm
- Ultra-thin: 0.05-0.1mm
- Thin gauge: 0.1-0.5mm
- Medium: 0.5-1.5mm
- Thick gauge: 1.5-3.0mm
Width Range: 5-1500mm, customizable
2.2 High-Precision Slitting Parameters
| Parameter | Standard Slitting | High-Precision | Ultra-High-Precision |
|---|---|---|---|
| Width Tolerance | ±0.30mm | ±0.05mm | ±0.02mm |
| Thickness Tolerance | ±0.02mm | ±0.01mm | ±0.005mm |
| Edge Burrs | ≤0.05mm | ≤0.02mm | ≤0.01mm |
| Surface Roughness Ra | ≤1.6μm | ≤0.8μm | ≤0.4μm |
2.3 Mechanical Properties
Annealed State (O State):
- Tensile Strength: 200-260MPa
- Elongation: ≥35%
- Hardness: 40-50HV
Semi-Hard State (H04):
- Tensile Strength: 260-320MPa
- Elongation: ≥20%
- Hardness: 50-65HV
Hard State (H06):
- Tensile Strength: ≥320MPa
- Elongation: ≥5%
- Hardness: ≥65HV
Selection Notes: Hard state copper foil has high strength but is more brittle and prone to cracking during winding. The appropriate state should be selected based on the actual winding process.
III. Production Process Flow
3.1 Raw Material Preparation
C11000 electrolytic copper plate is used as raw material, with copper content ≥99.90% and low impurity content to ensure stable electrical performance. Material certificate must be provided.
3.2 Rolling Process
Hot rolling → Cold rolling → Annealing and softening → Slitting and forming.
Key Control Points:
- Rolling force uniformity: Ensure uniform thickness
- Tension control: Prevent copper foil deformation
- Surface quality: Avoid scratches and indentations
3.3 High-Precision Slitting
High-precision slitting is the core process. Using disc shears or flying shears, along with precision guiding system, ensures cutting accuracy.
Control Points:
- Blade sharpness: Dull blade will increase burrs
- Upper and lower blade gap: Adjust to about 1/3 of material thickness
- Tension control: Prevent copper foil warping
3.4 Quality Inspection
Each Batch Inspection Items:
- Thickness, width, length
- Surface quality (visual + instrument inspection)
- Edge quality (burr height)
- Mechanical properties (sampling)
- Conductivity (sampling)
IV. Selection Guide
4.1 Selection by Voltage Level
| Voltage Level | Thickness Range | Width Tolerance | Recommended State |
|---|---|---|---|
| Ultra-high voltage (≥500kV) | 0.1-0.5mm | ±0.02mm | O state |
| High voltage (110-500kV) | 0.1-1.0mm | ±0.05mm | O state/H04 |
| Medium voltage (10-110kV) | 0.2-1.5mm | ±0.05mm | H04 |
| Low voltage (<10kV) | 0.3-3.0mm | ±0.10mm | H04/H06 |
4.2 Selection by Winding Process
Manual Winding: Ordinary high-precision slitting is sufficient.
Automatic Winding: High-precision slitting required, width tolerance within ±0.05mm.
Precision Winding: Ultra-high precision slitting required, width tolerance within ±0.02mm.
4.3 Selection by Application
High Voltage Transformer: Focus on thickness uniformity and edge quality, select O-state.
Electric Furnace Transformer: Focus on high temperature resistance, select semi-hard state.
High Frequency Transformer: Focus on conductivity and surface quality, select annealed state.
V. Industry Standards and Certifications
5.1 Implemented Standards
- GB/T 5231 – Processed Copper and Copper Alloys: Grades and Chemical Composition
- GB/T 2059 – Copper and Copper Alloy Strips
- IEC 60325 – Copper Foil for Electrical Transformers
- ASTM B372 – General Purpose Copper and Copper Alloy Plates and Strips
5.2 Quality Certification Requirements
Suppliers should possess: ISO 9001, ISO 14001, UL certification, RoHS compliance, and REACH compliance.
VI. Quality Inspection Methods
6.1 Routine Inspection Items
Dimensional Inspection:
- Thickness: Micrometer, accuracy 0.001mm
- Width: Vernier caliper, accuracy 0.02mm
- Length: Steel tape measure
Appearance Inspection:
- Surface defects: Scratches, indentations, oxide spots
- Edge quality: Burr height, warpage
6.2 Performance Inspection
Mechanical Properties: Tensile strength, elongation (universal testing machine), hardness (Vickers hardness tester)
Electrical Properties: Conductivity (eddy current conductivity meter), resistivity (four-probe method)
6.3 Storage and Transportation
Storage Conditions: Dry, ventilated warehouse, relative humidity ≤60%, avoid corrosive media and direct sunlight.
Packaging: Moisture-proof packaging (PE film + desiccant), shockproof filling, clear labeling (specifications, batch, date).
VII. Supplier Selection Recommendations
7.1 Key Evaluation Points
- Slitting Equipment: Professional high-precision slitting equipment
- Testing Capabilities: Complete quality testing system
- Delivery Capabilities: Stock of standard specifications
- Customization: Special specifications according to drawings
- Technical Support: Selection advice and technical services
7.2 Sample Testing
Conduct sample testing before bulk purchase:
- Dimensional inspection: Measure thickness and width within tolerance
- Edge inspection: Observe burrs under magnifying glass or microscope
- Winding test: Check for insulation layer damage
- Electrical test: Verify conductivity meets requirements
After sample tests pass, conduct small-batch trial purchases to confirm stable supply capacity.
7.3 Price and Quality Balance
High-precision slitting production costs include raw materials, process, testing, and packaging. Excessively low prices may indicate quality risks. Choose suppliers with reasonable cost-performance ratio while ensuring quality.
VIII. Common Specifications Reference
8.1 High Voltage Transformer Copper Foil
| Thickness | Width | State | Width Tolerance | Applications |
|---|---|---|---|---|
| 0.1mm | 50-200mm | O state | ±0.03mm | Ultra-high voltage winding |
| 0.2mm | 50-300mm | O state | ±0.05mm | High voltage winding |
| 0.3mm | 50-400mm | O state | ±0.05mm | High voltage winding |
| 0.5mm | 50-500mm | H04 | ±0.05mm | Medium voltage winding |
8.2 Electric Furnace Transformer Copper Foil
| Thickness | Width | State | Width Tolerance | Applications |
|---|---|---|---|---|
| 0.5mm | 100-400mm | H04 | ±0.05mm | Electric furnace transformer |
| 1.0mm | 100-500mm | H04 | ±0.05mm | Electric furnace transformer |
| 1.5mm | 100-600mm | H06 | ±0.08mm | Large electric furnace |
8.3 High Frequency Transformer Copper Foil
| Thickness | Width | State | Width Tolerance | Applications |
|---|---|---|---|---|
| 0.05mm | 10-100mm | O state | ±0.02mm | High frequency transformer |
| 0.1mm | 10-150mm | O state | ±0.03mm | High frequency transformer |
| 0.2mm | 20-200mm | O state | ±0.05mm | Medium frequency transformer |
Conclusion
Our company has 30 years of experience in exporting magnetic wire and metal foil. We specialize in high-precision slit copper foil for transformers with thickness range 0.05-3.0mm and width range 5-1500mm. Customization is available. Standard specifications are in stock with fast lead times. Samples can be shipped worldwide.
For selection support, please contact our technical team.
Contact Information:
Email: office@cnlpzz.com
WhatsApp: 0086-19337889070