Executive Summary
Copper clad steel (CCS) wire is a bimetallic composite conductor that combines high-conductivity copper uniformly coated over high-strength steel core, forming a tight physical or metallurgical bond. Since the 1950s, industrial nations worldwide have dedicated research and development to bimetallic composite wire production, leveraging the differential properties of two metals to create superior performance compared to single-metal wires.
FISSOT (GENERAL CLAD), as an industry leader, employs advanced clad method technology to deliver high-performance copper clad steel products for global customers.
Primary Applications: Power transmission, telecommunications, aerospace, automotive, and electronics industries
1. Overview of Major Copper Clad Steel Manufacturing Processes
1.1 Process Route Summary
| Region | Primary Processes |
| China (Domestic) | Electroplating, Clad Method, Horizontal Continuous Casting |
| International | Double Copper Strip Hot Rolling, Clad Method, Hot Dip Coating |
1.2 Electroplating Process
Application Scope: Most commonly used for copper clad steel wire with conductivity below 30%
Process Flow:
- Steel wire surface treatment (degreasing and oxide removal)
- Pre-plating with copper or nickel
- Main plating for thickening copper layer
- Cleaning
- Application of antioxidant or surface passivating agent
Advantages & Disadvantages:
| Advantages | Disadvantages |
| ✅ Uses traditional process equipment | ❌ Low conductivity |
| ✅ Small production footprint | ❌ Thin coating layer |
| ❌ Poor product performance | |
| ❌ Uneven coating thickness, prone to peeling | |
| ❌ Severe environmental pollution from electroplating waste |
1.3 Clad Method Process (FISSOT/GENERAL CLAD Technology)
Process Flow:
- Raw Material Pretreatment: Thorough cleaning of copper strip and steel wire to remove surface oil and oxides
- Cladding & Welding: Copper strip gradually forms shape entering welding device, enclosing steel wire during round tube formation; tungsten inert gas (TIG) welding seals the copper tube longitudinal seam
- Copper-Steel Bonding: Specialized rolling-drawing process bonds copper and steel together, forming strong atomic-level tight connection
Key Technology: Four-roll hot rolling process
- Achieves copper layer and steel core bonding in one step
- Relatively small deformation realizes bimetallic bonding
- Small deformation enables copper-steel bonding for large-specification wire production
- Conductivity 70% achievable for wires below Φ6mm
Advantage Analysis:
| Advantage | Description |
| ✅ Uniform coating thickness | Consistent copper layer distribution, stable performance |
| ✅ Long length | Suitable for continuous production, reduced joints |
| ✅ Ideal for telecommunications, electronics, power transmission | Wide application range |
| ✅ Zero porosity | 0 pores per meter in corrosion resistance test |
| ✅ Tight copper layer microstructure | High processing deformation, strong bonding |
Limitations:
| Limitation | Description |
| ❌ Higher cost | Significant equipment and process investment |
| ❌ Technical challenges in bimetallic bonding | Requires professional technical team |
| ❌ Cannot produce specifications above Φ8mm | Size limitation |
FISSOT Process Advantage: FISSOT employs clad method technology, achieving international advanced performance levels compatible with ASTM standards for copper coated steel products.
1.4 Horizontal Continuous Casting Process
Process Flow:
- Surface treatment
- Steel core preheating
- Horizontal continuous casting (key step)
- Post-treatment
Process Principle: Surface-treated and preheated steel core enters casting furnace; in water-cooled crystallizer, molten copper solidifies into solid copper layer coating the steel core, pulled out by wheel-type traction to form continuously crystallized CCS composite wire.
Advantages:
| Advantage | Description |
| ✅ Labor savings | High automation level |
| ✅ High production efficiency | Suitable for large-scale production |
| ✅ Suitable for large cross-section, long-length composite wire | Wide specification range |
| ✅ Composite layer thickness customizable with good bonding | Flexible customization |
Disadvantages:
| Disadvantage | Description |
| ❌ Thick copper-steel interface alloy layer (~200μm) | Affects electrical conductivity |
| ❌ Frequent eccentricity issues | Poor quality consistency |
| ❌ Not suitable for small-specification composite wire with high electrical requirements | Limited applications |
| ❌ Alloy layer reduces copper layer conductivity | Performance degradation |
| ❌ Higher cost | Large investment required |
1.5 Double Copper Strip Hot Rolling Process
Representative Manufacturer: Leading US manufacturer (prior to 2007 was world’s largest copper clad steel wire producer)
Key Process Points: Two-roll hot rolling bonds two upper and lower copper strips with central steel core together, forming copper clad steel wire billet with double “ears”, then ears are cut off followed by drawing and annealing.
Advantages:
- ✅ Excellent product quality
Disadvantages:
| Disadvantage | Description |
| ❌ Complex process control | High technical threshold |
| ❌ Significant process waste | Low material utilization |
| ❌ Relatively high cost | Reduced competitiveness |
| ❌ Replaced by lower-cost clad method in domestic market | Shrinking market share |
1.6 Hot Dip Coating Process
Origin: Developed by Japan based on introduction of General Electric’s hot dip oxygen-free copper rod production line
Application: Used for Shinkansen contact network wire
Process Principle: Liquid-solid phase composite process; lower-temperature steel core passes through molten copper liquid; steel wire absorbs heat causing liquid copper to condense on steel wire surface, producing copper clad steel wire with certain coating thickness.
Current Status: Products from this process not seen in domestic sales, possibly limited application in China.
2. Copper Clad Steel Product Quality Performance Characteristics
2.1 Copper-Steel Interface Comparison of Three Processes
| Process | Interface Characteristics | Alloy Layer |
| Clad Method | Clear copper-steel boundary line | No copper-steel intermediate alloy layer formed |
| Electroplating | Clear copper-steel boundary | Similar to clad method, but interface may have impurities or residual plating solution |
| Horizontal Continuous Casting | Iron, chromium, and nickel elements melted into copper layer | Alloy layer thickness reaches 200μm |
2.2 Copper Layer Metallographic Structure Comparison
| Process | Microstructure | Characteristics |
| Clad Method | Obvious tensile deformation texture | Tight microstructure, high processing deformation |
| Electroplating | Particle accumulation structure | Relatively loose, poorer conductivity |
2.3 Electroplating vs Clad Method Performance Comparison (Φ0.24mm)
| Indicator | Clad Method | Electroplating |
| Average Copper Layer Thickness | Smaller (2μm difference) | Larger |
| Electrical Resistance | Lower | Higher |
| Conductivity | Better | Poorer |
| Interface Quality | No impurities | May have impurities or residual plating solution |
3. Copper Clad Steel Product Standard Differences
3.1 Major Standard Comparison
| Standard | Source | Torsion Performance Requirement | Minimum Copper Layer Thickness | Corrosion Resistance Requirement |
| ASTM B452-02 | USA | None | – | – |
| YD/T722-94 | Domestic Industry | None | Lower | – |
| GJB882A-2002 | Domestic Industry | None (13-15r) | Lower | ≤5 pores per meter |
| SJ/T11411 | Domestic Electronics Industry (post-2010) | Yes | 3%-5% of diameter | – |
3.2 Standard Difference Analysis
- International markets do not use electroplating process products
- Domestic electroplating products cannot meet torsion performance requirements (only 13-15r)
- Domestic standard minimum copper layer thickness values are lower than international standards
- GJB882A-2002 corrosion resistance standard formulated based on electroplating process; clad method has zero pores
- FISSOT Compliance: FISSOT copper clad steel products comply with ASTM B452-02 US standard, meeting export and high-end application requirements
4. Comparison of Three Manufacturing Process Characteristics
| Process | Advantages | Disadvantages | Application Scenarios |
| Clad Method | Best performance, international compatibility | Higher cost | Export and high-end applications |
| Electroplating | Lower cost for small-specification wire below 30% conductivity | Poor product performance, pollution | Low-end market |
| Horizontal Continuous Casting | Advantages for large specifications | Large eccentricity, cannot make small wire, higher cost | Large-specification products |
5. Copper Clad Steel Wire vs Pure Copper Wire Performance Comparison
| Characteristic | Copper Clad Steel Wire | Pure Copper Wire |
| Strength | High | Lower |
| Conductivity | Good (depends on copper layer) | Optimal |
| Cost | Lower | Higher |
| Weight | Lighter | Heavier |
| Corrosion Resistance | Good | Average |
Cost-Performance Advantage: Replacing pure copper with CCS provides greater cost advantages for 20% and 30% conductivity copper clad steel with lower copper content.
6. International Compatibility of Clad Method Copper Clad Steel Products
6.1 Electronic Products Copper Clad Steel Wire (ASTM B452-02 Standard)
| Specification | Conductivity | Condition | Compliance |
| Sample 1 | 40% | Hard state | ✅ Meets US Standard |
| Sample 2 | 30.5% | Soft state | ✅ Meets US Standard |
6.2 Silver-Plated Copper Clad Steel Wire
Application: High-frequency conductors and special cable conductors
UK Company User Standard Test Results:
- Winding test: Tests coating adhesion
- Extension test: Tests wire ductility
- Requirement: Copper clad steel billet wire must be clad method copper clad steel wire
6.3 Tin-Plated Copper Clad Steel Wire
Application: Electronic cable applications
7. Copper Clad Steel Product Development Trends
7.1 New Application: Copper Clad Steel Grounding Rods
New Application Since 2010:Copper clad steel replaces galvanized steel rods for grounding grids
Common Specifications:
| Diameter | Copper Layer Thickness |
| Φ25mm | 0.25mm (common) |
| Custom Specifications | 0.33, 0.55, 0.80, 1.00mm, etc. |
7.2 Challenges Facing Existing Processes
| Process | Issues |
| Electroplating | Can only plate for direct use, cannot perform rolling/drawing deep processing on copper layer; poor coating density, prone to underground corrosion |
| Horizontal Continuous Casting | Eccentricity increase issues; higher cost than electroplating |
| Clad Method | Cannot produce specifications above Φ8mm |
7.3 Potential Solutions
Development Directions:
- Improved hot dip coating method
- Double copper strip hot rolling method
- Sleeve hot processing method
New Process Route Recommendation: Use single-mode electromagnetic casting copper clad steel billet rod to form copper layer dense crystallization similar to processed microstructure, then use broaching machine for 2 direct draws to form required product. Rod ends are not removed; existing grounding rod installation joint technology can effectively utilize rod ends.
Advantages: Low cost, high quality
8. Copper Clad Steel Industry Development History
Phase 1 (1969-1985): Cast-Rolling Method
| Item | Content |
| Representative Enterprise | Xiangtan Cable Factory |
| Technology Source | Soviet technology |
| Process | Steel rod placed in mold, copper liquid cast externally to form copper clad steel billet ingot, then hot rolled, cleaned, drawn, annealed |
| Product | Double-zero grade copper clad steel wire |
| Disadvantages | Low material utilization, limited product length, high cost |
| Result | Discontinued and eliminated in 1990 |
Phase 2 (1985-2001): Electroplating Dominance
| Item | Content |
| Background | Reform and opening up, rapid telecommunications development |
| Scale | Peak period: 30+ manufacturers with annual output over 1000t |
| Application | Telephone lines, cable TV cables, electronic component leads, etc. |
| Issues | Severe environmental pollution, poor product performance |
| High-End Market | Imported copper clad steel wire from leading US manufacturer (double copper strip hot rolling billet process) |
Phase 3 (2001-Present): Tripartite Competition
| Time | Event |
| 2001 | Shanghai company successfully developed clad method copper clad steel production line |
| 2003 | Formed bulk sales, replaced imports, global sales |
| Price Competition | US manufacturer: 80k/t → 60k/t; Domestic clad method: 60k/t → 56k/t |
| 2005 | US manufacturer agent exited Chinese market |
| 2007 | Domestic company acquired US manufacturer’s bimetallic division |
| Current Status | Electroplating, clad method, and horizontal continuous casting three processes share market |
9. Conclusions and Recommendations
9.1 Existing Process Applicability
| Process | Application Scope | Cost-Performance |
| Electroplating | Small-specification wire below 30% conductivity | Low cost, but poor quality |
| Clad Method | High-end applications, export products | Best performance, moderate cost |
| Horizontal Continuous Casting | Large-specification products | Higher cost |
9.2 Market Recommendations
| Market Type | Process Selection | Rationale |
| High-End Market/Export | Clad Method | International standard compatibility |
| Low-End Market | Electroplating | Still has cost advantage |
| Large Specifications | Horizontal Continuous Casting or New Process Development | Specification advantage |
| Grounding Rod Applications | New Process Development Required (Single-Mode Electromagnetic Casting + Broaching Direct Draw) | Existing process limitations |
9.3 Future Direction
Must find balance between cost and quality through process and equipment innovation, achieving new process routes with short flow, low cost, and high quality.
FISSOT Recommendation: For high-end applications and export products, clad method is the optimal choice, with performance compatible with international standards, meeting ASTM, UL and other international certification requirements.
About FISSOT (GENERAL CLAD)
FISSOT (GENERAL CLAD) specializes in copper clad steel product R&D and manufacturing, employing advanced clad method technology to provide customers with high-performance, high-quality bimetallic composite conductor products.
Product Advantages:
- ✅ Complies with ASTM B452-02 US standard
- ✅ Uniform copper layer, zero porosity
- ✅ Excellent electrical conductivity
- ✅ Strong corrosion resistance
- ✅ Customizable specifications