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C14700 Sulfur Copper — also designated UNS C14700 — is a high-purity copper alloy containing approximately 0.20–0.50% sulfur (S) as its primary alloying element. Unlike conventional oxygen-free copper or tellurium copper variants, C14700 achieves an exceptional balance between electrical conductivity, thermal conductivity, and machinability. Its electrical conductivity typically reaches 96–98% IACS (International Annealed Copper Standard), making it one of the most conductive free-machining copper alloys available on the market today.
The addition of sulfur promotes the formation of fine copper sulfide (Cu₂S) particles uniformly distributed throughout the copper matrix. These microscopic inclusions act as chip-breakers during high-speed CNC machining, dramatically improving tool life and surface finish quality — all without significantly compromising the alloy's conductivity or mechanical strength. This unique combination makes C14700 an ideal candidate for precision-machined electrical components that demand both high electrical performance and manufacturing efficiency.
C14700 Sulfur Copper delivers near-pure-copper conductivity while enabling chip-free, high-speed CNC machining — a critical combination for producing EV charging connectors, terminals, and contact pins at industrial scale with minimal waste and maximum throughput.
Compared to C14500 (Tellurium Copper) and C18200 (Chromium Copper), C14700 offers a more environmentally favorable profile since sulfur is a non-toxic alloying element. This aligns with the increasingly stringent RoHS and REACH compliance requirements across the global EV supply chain, where OEMs and Tier-1 suppliers are actively seeking lead-free, cadmium-free, and hazardous-substance-free materials for charging infrastructure components.
| Property | Value / Range | Significance for EV Charging |
|---|---|---|
| Electrical Conductivity | 96–98% IACS | Minimizes resistive heat generation in connectors under high-current DC fast charging |
| Thermal Conductivity | ~360 W/(m·K) | Efficient heat dissipation in high-power charging terminals (up to 350 kW) |
| Tensile Strength | 240–310 MPa | Sufficient mechanical durability for repeated plug-in/plug-out cycles |
| Hardness (HRB) | 40–65 | Maintains contact surface integrity over 10,000+ mating cycles |
| Machinability Rating | 85% (vs. C36000 = 100%) | Enables high-speed CNC production of complex connector geometries |
| Sulfur Content | 0.20–0.50 wt% | RoHS-compliant, non-toxic alloying element — suitable for global EV markets |
| Density | 8.9 g/cm³ | Consistent with standard copper alloy design parameters |
| Operating Temperature | Up to 300°C | Compatible with high-temperature environments in fast-charging stations |
The global electric vehicle charging infrastructure market is experiencing explosive growth. According to industry analysts, the global EV charging station market was valued at approximately USD 17 billion in 2023 and is projected to surpass USD 100 billion by 2030, registering a compound annual growth rate (CAGR) of over 30%. This unprecedented expansion is being driven by government mandates — including the U.S. Bipartisan Infrastructure Law (allocating $7.5 billion for EV charging), the EU's Alternative Fuels Infrastructure Regulation (AFIR), and China's 14th Five-Year Plan for new energy vehicle infrastructure.
At the heart of every EV charging station — whether a Level 2 AC charger or a 350 kW DC ultra-fast charger — lies a complex network of electrical connectors, terminal blocks, relay contacts, bus bars, and cable assemblies. These components must handle continuous high-current loads (from 32A for Level 2 up to 500A+ for ultra-fast DC systems), endure tens of thousands of mechanical mating cycles, resist corrosion in outdoor environments, and comply with international safety standards including IEC 62196, SAE J1772, CHAdeMO, and the emerging NACS (North American Charging Standard).
This is precisely where the material selection becomes mission-critical. Traditional brass alloys (C36000) offer excellent machinability but sacrifice conductivity (only ~26% IACS). Pure copper (C10100/C11000) provides maximum conductivity but is notoriously difficult to machine at high speeds. C14700 Sulfur Copper bridges this gap, delivering near-pure-copper electrical performance with machinability scores that rival brass — making it the material of choice for precision EV charging components manufactured at industrial scale.
CCS Combo, CHAdeMO, and NACS connector pins require sub-millimeter precision machining with tight dimensional tolerances (±0.005mm). C14700's chip-breaking sulfide inclusions enable single-pass CNC turning at high feed rates, reducing cycle time by up to 40% versus oxygen-free copper while maintaining the conductivity needed for 150–350 kW power delivery.
High-current bus bars in commercial charging stations distribute power from grid input to multiple charging outlets. C14700 bus bar profiles — available as extruded rods, flat bars, and custom cross-sections — provide the current-carrying capacity of pure copper while offering the dimensional accuracy required for automated assembly in charging station manufacturing lines.
Battery management systems (BMS) rely on high-performance relays and contactors to safely connect and disconnect the battery pack. C14700 contact tips and terminal components offer the low contact resistance (<1mΩ) and arc erosion resistance needed for the millions of switching cycles expected over an EV's service life.
Ultra-fast charging cables (350 kW+) require active liquid cooling to prevent overheating. C14700 machined fittings and manifold components within these cooling assemblies leverage the alloy's exceptional thermal conductivity (~360 W/m·K) to maximize heat transfer efficiency, enabling sustained high-power charging without thermal throttling.
Public charging pile (EVSE) assemblies incorporate dozens of precision electrical contacts for power switching, communication interfaces, and safety interlocks. C14700's combination of high conductivity and excellent plating adhesion (for gold, silver, or nickel surface treatments) makes it the preferred substrate for these critical interface components.
Electric bus and commercial vehicle fleet charging increasingly uses overhead pantograph charging systems delivering 300–600 kW. The sliding contact strips and current collector components in these systems demand materials with both high conductivity and wear resistance — a profile perfectly matched by C14700 sulfur copper alloy.
The CharIN Megawatt Charging System (MCS) standard targets 3.75 MW power delivery for heavy-duty trucks and commercial vehicles. At these power levels, connector and cable materials must handle 3,000A+ continuous current — placing extreme demands on conductivity and thermal management. C14700's near-pure-copper conductivity positions it as a primary candidate for MCS connector component manufacturing.
As EV manufacturers and charging infrastructure OEMs commit to carbon neutrality, material supply chains are being scrutinized for hazardous substances. C14700's sulfur-based alloying system is fully RoHS and REACH compliant, providing a competitive advantage over lead-containing free-machining coppers (C14500, C36000) in markets with strict environmental regulations.
The scale of EV charging rollout — millions of connectors annually — demands materials compatible with fully automated Swiss-type CNC machining centers operating at maximum spindle speeds. C14700's machinability rating of 85% enables lights-out manufacturing with consistent chip formation, reducing machine downtime and scrap rates in high-volume connector production facilities.
Next-generation EV connectors are trending toward smaller form factors with higher current density — requiring materials that maintain structural integrity at reduced cross-sections while preserving conductivity. Advanced C14700 alloy formulations with optimized sulfide particle distribution enable the production of miniaturized contacts with wall thicknesses below 0.3mm without compromising electrical performance.
Post-pandemic supply chain disruptions have accelerated the trend toward regional sourcing of critical materials. Kepai's production facility in Sichuan, China positions it as a strategic supplier for Asia-Pacific EV charging infrastructure projects, while its international certifications enable direct supply to European and North American OEMs seeking qualified alternative sources for copper alloy components.
Vehicle-to-Grid (V2G) technology requires charging infrastructure components to handle bidirectional power flow with minimal energy loss. The ultra-low resistivity of C14700 sulfur copper directly reduces I²R losses in V2G connector assemblies, improving round-trip efficiency and reducing heat generation — critical factors for the long-term reliability of bidirectional charging systems.
Sichuan Kepai New Materials Co., Ltd., established in 2017, is a high-tech enterprise integrating research and development, production, and sales. Currently, the factory covers an area of approximately 9,000 square meters, with an office space of about 1,000 square meters.
The company primarily engages in the production of strategic emerging new materials for the national 13th Five-Year Plan, including special copper alloys such as tellurium copper, high-conductivity oxygen-free copper, silver copper, and dispersion copper, while also focusing on the research and development of high-conductivity, easy-to-machine, high-strength copper alloys.
The products are mainly applied in high-tech fields such as new energy vehicles, 5G technology, laser cutting, and lithium battery relays.
Innovation-driven development, quality wins the market
Technological innovation is the core competitiveness of Sichuan Kepai New Materials Co., Ltd. The company has a research and development and production team composed of senior industry experts who keep pace with international cutting-edge technology trends and continuously explore the unknown boundaries in the field of new copper alloy materials. Through a combination of independent research and development and industry-university-research collaboration, Kepai has made breakthrough progress in several areas, including high-performance tellurium copper, lead copper, and sulfur copper. Many of its technological achievements have reached international advanced levels and have been successfully applied in various industries such as new energy vehicles, precision machining parts, plasma cutting, relays, and energy storage, earning widespread recognition and praise in the market.
Kepai's product line is rich and diverse, covering a comprehensive range of solutions from basic materials to high-end customization. We focus on providing customers with high-performance, high-quality high-end copper alloy products, including but not limited to pure copper, oxygen-free copper, oxygen-free high-conductivity tellurium copper, nickel tellurium copper, tin bronze, beryllium copper, lead bronze, sulfur copper, and chromium zirconium copper. These products play an important role in reducing production costs and enhancing product performance due to their excellent physical and chemical properties and environmental friendliness, creating significant economic and social benefits for customers.
In the face of global market competition, Sichuan Kepai New Materials adheres to the development strategy of "rooted in Sichuan, radiating nationwide, and moving towards the world." By continuously optimizing market layout and improving the sales network, we have established a stable customer base in multiple provinces and cities across the country and have formed long-term cooperative relationships with several internationally renowned enterprises. At the same time, the company actively expands into overseas markets, participates in international competition and cooperation, and strives to promote Kepai's brand influence on the global stage.
We understand that the long-term development of an enterprise is inseparable from an excellent corporate culture. We advocate the corporate spirit of "integrity, innovation, collaboration, and win-win," encouraging employees to explore boldly and innovate courageously, while also emphasizing teamwork and talent cultivation, striving to create a harmonious, open, and inclusive work atmosphere. We believe that only by continuously pursuing excellence and creating value can we win the trust of customers and the respect of society.
Smelting
laying-off
extrusion
drawing
straightening
package
eddy current conductance instrument
Chemical composition test room
Metallographic sample polishing machine
Microcomputer controlled electro-hydraulic servo universal testing machine
Liquid crystal display electronic universal testing machine
Hardness tester
Looking ahead, Sichuan Kepai New Materials Co., Ltd. will continue to uphold its original intention, with even greater enthusiasm and determination, to engage in research and application in the field of new materials, contributing to the development of the new copper alloy materials industry in China and globally. We look forward to working hand in hand with friends from all walks of life to create a brilliant future together!
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