Copper plate: "all-rounder in electrical conductivity and corrosion resistance" among metal materials

As one of the earliest metal materials used by humans, copper plates still play an irreplaceable role in modern industry after thousands of years. From ancient currency casting to today's 5G chip packaging, copper plates have built multiple application scenarios in the fields of electronic information, architectural decoration, energy and transportation with their excellent conductivity, corrosion resistance and processing adaptability. From 99.9% pure copper sheets to complex brass plates with added alloy elements, copper plates continue to meet the stringent requirements of high-end manufacturing for material performance through composition design and process innovation.
1. Definition and classification system of copper plates
Definition: Copper plates refer to plate-shaped metal materials with copper as the matrix (copper content ≥ 60%), and their performance is regulated by alloying (adding zinc, tin, aluminum and other elements) and heat treatment. According to GB/T 2040-2017 standard, the thickness of copper plate usually ranges from 0.2-100mm, and the width can reach 3000mm. It has excellent electrical conductivity (electrical conductivity ≥ 90% IACS), thermal conductivity (≥ 370W/m・K) and atmospheric corrosion resistance.
Classification by production process and surface treatment
Production process:
Hot-rolled copper plate: heated to 800-950℃ and rolled, thickness ≥ 2mm, used for structural parts;
Cold-rolled copper plate: rolled at room temperature, thickness 0.2-10mm, high surface accuracy, used for precision parts;
Annealed copper plate: recrystallized annealing after cold rolling, stress elimination, and plasticity recovery;
Composite copper plate: copper and steel/aluminum composite rolling, such as copper-steel composite plate for grounding devices.
Surface treatment:
Passivation treatment: Chromate passivation forms a rainbow film to prevent discoloration;
Tin plating: Tin layer thickness 5-10μm, used for food packaging;
Painting treatment: Fluorocarbon paint coating, used for building curtain walls;
Mirror polishing: Roughness Ra≤0.2μm, used for decorative mirrors.
2. Production process and key technological breakthroughs
Full process process analysis
Smelting and casting:
Pure copper is smelted in a reverberatory furnace or induction furnace, and the impurity content is controlled at ≤0.05%;
Complex alloy copper plates (such as QAl9-4) are smelted in a vacuum induction furnace to reduce the volatilization of alloy elements;
Continuous casting technology: The upper-draw method is used for continuous casting to produce φ8-20mm copper rod billets, and the lower-draw method is used to produce slab billets (thickness ≤200mm). The crystallizer is made of graphite and the cooling water temperature is controlled at 30-50℃.
Rolling and finishing:
Hot rolling stage: the copper ingot is heated to 850-900℃, and rolled to a thickness of 5-20mm on a four-roll reversible rolling mill, with a pass reduction rate of ≤30%;
Cold rolling stage: a twenty-roll Sendzimir rolling mill is used to roll 0.1mm ultra-thin copper plates, and the rolling oil temperature is controlled at 40-60℃ to ensure surface quality;
Heat treatment process:
Recrystallization annealing: pure copper plates are annealed at 300-350℃ for 1 hour to eliminate work hardening;
Aging treatment: beryllium bronze plates are aged at 320-350℃ for 2 hours to precipitate CuBe phase and increase strength to σb≥1200MPa.
Surface treatment technology:
Chromium-free passivation: Silane treatment is used to replace chromate, the film thickness is 0.5-1μm, and the salt spray test (500 hours) shows no discoloration;
Nano coating: TiO₂ nanolayer is deposited on the surface of the brass plate to achieve self-cleaning function (photocatalytic decomposition of organic matter);
Laser roughening: Micron-level pits are formed on the surface of the copper plate by laser to improve lubrication performance and is used for deep drawing parts.
Cutting-edge technology cases
Continuous extrusion molding: CNMC Orbet uses the CONFORM continuous extrusion process to produce copper plates and strips, which reduces energy consumption by 15% compared to traditional rolling and increases the yield rate to 98%;
Digital rolling mill: The intelligent rolling mill deployed by Luoyang Copper Processing Group adjusts the rolling force in real time through AI algorithms, and controls the thickness tolerance of 0.3mm brass plates to ±0.005mm;
Copper plates for 3D printing: The CuCrZr alloy plates developed by the Shenyang Institute of Metal Research, Chinese Academy of Sciences, are purified through electron beam melting, with an oxygen content of ≤20ppm, and are suitable for substrate materials for metal 3D printing.
3. Performance advantages and engineering applications
Integrated circuit packaging:
The lead frame uses C194 copper alloy plate (thickness 0.15mm), and the electrical connection between the chip and the circuit board is achieved through nickel-gold electroplating. The thermal expansion coefficient (17×10^-6/℃) matches the silicon chip;
5G base stations use T2 copper plates (thickness 2mm) to make heat sinks, with a thermal conductivity of 398W/m・K, which is 30% higher than the heat dissipation efficiency of aluminum alloy.
Power system:
The transformer uses T2M soft copper plates (thickness 1.5mm) to make conductive bars, with a current carrying capacity of 600A/mm² and a resistance 40% lower than that of aluminum bars;
Superconducting cables use copper-clad aluminum composite plates with a copper layer thickness of 0.5mm to provide mechanical support and short-circuit protection.
Architecture and decoration field
Landmark buildings:
H65 brass plate (thickness 1.2mm) is used for the curtain wall of Shanghai Tower. After antique treatment, the annual corrosion amount is ≤0.005mm;
T3 copper plate (thickness 0.8mm) is used for the roof of Suzhou Museum. After oxidation, a blue-green copper rust layer is formed, which is in harmony with the garden landscape.
Innovative applications:
Beijing Daxing International Airport uses B10 white copper plate (thickness 2mm) to make heat exchange tubes for seawater desalination equipment, which is resistant to chloride ion corrosion (Cl-≤5000ppm);
QSn4-3 bronze plate (thickness 3mm) is used for engraving decorative patterns in Dubai Burj Al Arab, with a hardness of 120HB and resistance to wind and sand wear.
Industry and Energy Field
Marine Engineering:
China's "Deep Sea No. 1" Energy Station uses QAl9-4 aluminum bronze plate (thickness 10mm) to make seawater pump impellers, which have a service life of 8 years in sandy seawater (sand content ≤0.5kg/m³);
The cross-sea bridge uses B30 white copper plate (thickness 3mm) to make sacrificial anodes to protect steel piles from seawater corrosion, with a current efficiency of ≥90%.
New Energy:
CATL Battery Pack uses T2 copper plate (thickness 0.3mm) to make pole ears, with a welding strength of ≥150N, meeting the requirements of 1000 cycles of charge and discharge;
Photovoltaic inverters use H62 brass plates (thickness 1.5mm) to make heat dissipation substrates, and improve welding reliability through tinning treatment (tin layer thickness 8μm).
Transportation and Shipbuilding
Railway transportation:
CRRC Sifang high-speed rail trains use T2M copper plates (thickness 0.5mm) to make contact network slides, with a friction coefficient of 0.15-0.2 with rails, and a wear loss of ≤0.1mm/10,000 km;
Metro screen doors use H68 brass plates (thickness 1.2mm), which are passivated and rust-free in underground humid environments (humidity ≥90% RH) for 5 years.
Shipbuilding:
China's first polar research vessel "Xuelong 2" uses QSn7-0.2 tin bronze plates (thickness 8mm) to make seawater valve seats, which are resistant to seawater impact corrosion and have an operating temperature of ≤120℃;
Cruise ship decorations use H85 brass plates (thickness 0.8mm), which are knurled and have an anti-slip coefficient of ≥0.6, meeting maritime safety regulations.
IV. Market dynamics and technological trends
Global industry status
Capacity distribution: In 2024, the global copper plate production will be about 12 million tons, of which China will account for 58% (Jiangxi, Guangdong and Henan are the main production areas), followed by Japan (12%), the United States (10%) and Germany (6%);
Price dynamics: The average price of T2 copper plate (1.0mm×1000×2000mm) in 2024 is about US$12,000/ton, which is 11% higher than that in 2023 due to the LME copper price (US$8,500-9,500/ton);
Import and export pattern: China exports about 1.5 million tons of copper plates annually, mainly to Southeast Asia (accounting for 35%), and imports about 800,000 tons, mainly for high-end electronic copper plates (such as Japan JX Metal's C19500 copper alloy plate, which is 50% higher than domestic products).
Technology development direction
Green manufacturing technology:
Recycled copper smelting: Use waste copper to directly smelt and produce copper plates, which reduces energy consumption by 85% compared with primary copper. For example, Chujiang New Materials' recycled copper utilization rate reaches 95%;
Low-temperature rolling: Use 650℃ low-temperature rolling for H62 brass plates, which reduces energy consumption by 12%, while refining the grain size to 10μm and increasing strength by 15%;
Chromium-free electroplating: Develop tin-nickel alloy electroplating to replace hexavalent chromium electroplating for copper plate surface protection, in compliance with the EU RoHS directive.
High-performance innovation:
High thermal conductivity copper plate: T2Ag alloy plate with 0.5% silver added, thermal conductivity increased to 420W/m・K, used for 5G chip heat dissipation;
High-strength and high-conductivity copper plate: Cu-0.8Al₂O₃ alloy plate with dispersion strengthening (Al₂O₃ particles), σb≥400MPa, conductivity≥85% IACS, used for high-speed train contact network;
Memory function copper plate: Development of Cu-Al-Ni shape memory alloy plate, recovery rate ≥95%, used for automatic sealing of pipeline connections.
Intelligent manufacturing:
Intelligent detection of copper plate surface defects: AI visual system is used to identify scratches and pits larger than 0.1mm with an accuracy of 99.3%;
Digital twin rolling: A digital twin model of the copper plate rolling process is established to predict the plate shape deviation of ≤0.03mm, reducing the number of trial rolling by 70%;
Blockchain traceability: Blockchain technology is applied to high-end electronic copper plates to record the full process data from copper mines to chips, meeting ISO 16949 certification requirements.
Functional surface engineering:
Antibacterial copper plate: T2Ag plate with 0.8% silver added has a killing rate of ≥99% for Escherichia coli and Staphylococcus aureus, and is used for hospital handrails;
Self-lubricating copper plate: Micro-grooves are laser-etched on the surface and molybdenum disulfide is embedded, and the friction coefficient is reduced from 0.6 to 0.2, which is used for oil-free bearings;
Photocatalytic copper plate: H62 plate coated with TiO₂ photocatalytic coating has a formaldehyde degradation efficiency of ≥90% under ultraviolet irradiation, and is used for interior decoration.
V. Selection Guide and Maintenance Points
Selection Decision Factors
Conductive/thermal conductivity requirements:
High conductivity scenarios (such as cables): select T2, T3 pure copper plates, conductivity ≥ 97% IACS;
Heat dissipation scenarios (such as LEDs): select T2 or CuCr1 alloy plates, thermal conductivity ≥ 370W/m・K;
Resistor elements: select B10, B30 nickel silver plates, resistivity (0.4-0.9)μΩ・m, temperature coefficient ≤ 200×10^-6/℃.
Environmental adaptability:
Atmospheric environment: select H62 brass plates for ordinary buildings, and select B10 nickel silver plates for coastal areas;
Seawater environment: QSn7-0.2 bronze plates or B30 nickel silver plates for ships;
Chemical environment: select QAl9-4 aluminum bronze plates, acid corrosion resistance (pH=2-12).
Processing requirements:
Deep drawing: select H68 soft brass plate (r value ≥ 1.8);
Cutting: select HPb59-1 lead brass plate (add 1.5% lead, cutting speed increased by 30%);
Welding connection: select T2 pure copper plate (oxygen content ≤ 0.02%) to avoid welding cracks.
Storage and maintenance technology
Rust-proof storage:
Short-term storage (≤ 3 months): apply water-based rust inhibitor (concentration 3-5%), the cost is about 1 yuan / square meter;
Long-term storage (> 1 year): wrap with VCI vapor phase rust-proof paper, humidity ≤ 30% RH, temperature 15-25℃;
Sea transportation protection: the copper plate surface is coated with dry anti-rust oil, wrapped with moisture-proof paper, and silica gel desiccant is placed in the container (dosage 500g / ton).
Surface maintenance:
Daily cleaning: Wipe with a neutral detergent (pH6-8), and avoid using steel wool to damage the passivation film;
Patina treatment: The patina on the surface of the building copper plate can be cleaned with a 5% citric acid solution (temperature 40-50℃, time 5-10 minutes), and then coated with a transparent protective paint;
Coating repair: When the tin layer is damaged, it can be repaired locally by brush plating technology, and the thickness of the tin layer is controlled at 5-8μm.
Special environment maintenance:
Marine engineering: Rinse the surface of the copper plate with high-pressure water (pressure ≥10MPa) every year to remove marine organisms;
Industrial atmosphere: Neutralize surface acidic pollutants with a 10% trisodium phosphate solution every quarter;
Electronic equipment: Wipe the surface of the copper plate with anhydrous ethanol to remove oil and oxides to ensure welding reliability.

As a metal material with both historical thickness and technological vitality, the copper plate is being reborn in the era of carbon neutrality and digitalization through green, intelligent and functional innovations. From the bronze ritual vessels of ancient civilizations to the copper interconnection technology of modern chips, copper plates have always been writing the evolutionary epic of human material applications with their unique metallic charm and practical value, providing a solid material foundation for high-end manufacturing and a better life.