Copper sheet: a high-performance metal sheet that combines functionality and aesthetics

Copper sheet is a sheet product made from pure copper or copper alloys through smelting, rolling, and heat treatment. Copper's unique high electrical and thermal conductivity, excellent ductility, and distinctive metallic luster make it a specialized metal sheet that combines both functionality and aesthetics in applications such as electronics, architectural decoration, industrial heat dissipation, and precision manufacturing. It cannot be fully replaced by materials like steel and aluminum.

I. Definition and Classification of Copper Sheet

The core of copper sheet classification revolves around purity/alloy composition and production process. Different types have distinct characteristics, suited to different functional requirements:

(I) Classification by Material Purity/Alloy Composition (Core Classification Dimension)

Pure copper sheet (red copper sheet): Copper content ≥ 99.5% (common grades T1, T2, and T3), named for its purple-red surface, offers excellent electrical and thermal conductivity (conductivity ≥ 98% IACS, thermal conductivity ≥ 380 W/(m・K)) and ductility (elongation ≥ 40%). Features: Higher purity yields greater electrical and thermal conductivity, but lower strength (tensile strength ≤ 220 MPa) and prone to oxidation (forming a protective film of copper oxide or verdigris on the surface).
Typical Applications: Conductive components of electronic devices (circuit boards, busbars), heat sinks for precision instruments, and base materials for commemorative coins and medals.
Brass Sheet: Copper-zinc alloy sheet (zinc content 3%-45%). Common grades include H62 (62% copper + 38% zinc), H65 (65% copper + 35% zinc), and H90 (90% copper + 10% zinc). It has a golden-yellow surface, is stronger than pure copper sheet, and offers excellent value for money.​
Specific Characteristics:

Low-zinc brass (H90): Ductility approaches that of pure copper, making it suitable for stamping and forging, and used in decorative components (brass doors, copper handrails).

Medium-zinc brass (H62/H65): Balanced strength and ductility, with good machinability, is used in hardware (bolts, nuts), sanitary ware, and musical instruments (trumpets, flutes).

Advantages: Lower price than pure copper plate, and better corrosion resistance (susceptible to rust in neutral environments). Bronze Plate: An alloy of copper with other elements such as tin, aluminum, silicon, and beryllium. These plates are not made from a single component and are named according to the alloying elements. Their properties vary significantly:

Tin Bronze Plate (QSn4-3): Contains 4% tin and 3% zinc. It offers excellent wear and fatigue resistance and is used in bearing bushings, gears, and precision molds.

Aluminum Bronze Plate (QAl9-4): Contains 9% aluminum and 4% iron. It offers high strength (tensile strength ≥ 600 MPa) and resistance to seawater corrosion. It is used in marine engineering components (ship propellers and valves).

Beryllium Bronze Plate (QBe2): Contains 2% beryllium. After heat treatment, it achieves extremely high hardness (HRC ≥ 35) and excellent electrical conductivity. It is used in precision springs, contactors, and explosion-proof tools (it is non-magnetic and spark-resistant). White copper sheet: A copper-nickel alloy sheet (nickel content 10%-30%). Common grades include B10 (90% copper + 10% nickel) and B30 (70% copper + 30% nickel). It has a silvery-white surface and is extremely corrosion-resistant (especially to seawater, acids, and alkalis). Its thermal conductivity is lower than that of pure copper.

Applications: Pipes, valves, and heat exchangers for marine environments; medical devices (scalpels and stethoscopes); and high-end decorative items (imitation silver jewelry and instrument panels).

(II) Classification by Production Process (Influencing Precision and Surface Condition)

Hot-rolled copper sheet: Made from copper billets rolled at high temperatures (800-900°C), it has a relatively thick thickness (3-100mm) and a high surface roughness (Ra ≤ 6.3μm). It has medium strength and is suitable for subsequent forging and cutting.

Applications: Thick-walled copper sleeves, large copper structural components, and heat dissipation substrates for industrial equipment (where high surface precision is not required). Cold-rolled copper sheet: Made from hot-rolled copper sheet, cold-rolled (in multiple passes) at room temperature. It boasts a thin thickness (0.1-3mm), a smooth surface (Ra ≤ 1.6μm), high dimensional accuracy (thickness deviation ≤ ±0.01mm), and enhanced ductility.

Applications: Electronic circuit boards, precision heat sinks, and decorative thin copper sheet (such as copper foil substrates and metal paintings).

Sub-categories: After cold rolling, it can be annealed (to reduce hardness and restore plasticity) or polished (to achieve a mirror finish, Ra ≤ 0.8μm) to meet diverse processing requirements.
II. Core Performance Characteristics of Copper Plates (Highlighting Copper's Unique Advantages)
Excellent Electrical and Thermal Conductivity: Pure copper plate has an electrical conductivity five times that of mild steel and 1.6 times that of aluminum, making it the preferred choice for low-loss electrical conductivity in the electronics and electrical appliance industry. Its thermal conductivity is eight times that of steel and 1.3 times that of aluminum, making it ideal for heat dissipation in high-power devices (such as CPU heat sinks and new energy vehicle battery cooling plates). For example, a 1mm thick T2 pure copper plate can conduct 100°C of heat to its surface in one second, achieving heat dissipation efficiency far exceeding that of other metals. Excellent ductility and workability: Pure copper sheets can be cold-stretched to over three times their original length without breaking and can be stamped into complex shapes (such as ultra-thin copper foil and shaped conductive sheets). Brass and bronze sheets can be precisely processed through cutting, forging, and welding to accommodate a wide range of sizes, from small ornaments to large ship components. For example, H62 brass sheets can be stamped into 0.1mm thick bathroom faucet fittings without a crack.

Unique corrosion resistance and stability: In dry air or a neutral environment, copper forms a dense protective film of copper oxide or basic copper carbonate (verdigris) on its surface, preventing further corrosion. Cupronickel and aluminum bronze sheets can withstand long-term use in seawater and acidic and alkaline environments (the corrosion rate of B30 cupronickel in seawater is only 1/100 that of carbon steel). They require no frequent painting or maintenance and have a service life of over 50 years. A combination of aesthetics and functionality: The purplish-red color of pure copper, the golden yellow of brass, and the silvery-white of cupronickel possess a natural metallic luster, making them suitable for decorative applications without the need for additional coating. Furthermore, copper's luster slowly changes over time (e.g., the vintage texture created by patina), making it a natural decorative color for high-end architecture and artworks. For example, after 10 years of use, a copper curtain wall will develop a uniform patina, lending it a unique sense of history.

Non-magnetic and antibacterial properties: Pure copper and most copper alloys (such as brass and cupronickel) are non-magnetic, making them suitable for precision instruments (e.g., compasses and radar components). Copper ions also possess antibacterial properties (≥99% against E. coli and Staphylococcus aureus), making them suitable for use in medical devices and food-contact components (e.g., copper cutlery and baby bottle accessories).
III. Main Application Areas of Copper Plate (Focusing on Applications Suitable for Copper Properties)
Electronic and Electrical Appliances (Core Functional Applications):
Conductive Components: T2 pure copper plate is used for circuit board substrates and busbars in power transmission and transformation equipment (it has high current carrying capacity and reduces transmission losses); ultra-thin cold-rolled pure copper plate (thickness 0.1-0.3mm) is used for internal conductive plates in mobile phones and computers;
Heat Dissipation Components: Pure copper plate is used to make CPU heat sinks and LED street light heat dissipation substrates (it conducts heat quickly and prevents overheating); battery cooling plates in new energy vehicles are often made of H62 brass plate (it offers both thermal conductivity and strength);
Precision Components: Beryllium copper plate is used for relay springs and contactor contacts (it offers high strength and conductivity, with a service life of over 100,000 cycles); Tin bronze plate is used for motor bearing bushings (it is wear-resistant and reduces operating noise).
Architecture and Decoration (Aesthetics + Corrosion Resistance):
High-end Decoration: Pure copper and brass plates are used for copper doors, handrails, and elevator door panels (the metallic luster lasts, eliminating the need for electroplating). Copper curtain walls (such as parts of the exterior walls of the Beijing National Centre for the Performing Arts) utilize T2 pure copper plates, which develop a patina over time, creating a unique style.
Architectural Components: Cupronickel plates are used for roofs and rainwater pipes in coastal areas (resistance to seawater corrosion, preventing rust and leaks). Aluminum-bronze plates are used for shock-absorbing components in bridges (high strength and fatigue resistance, suitable for long-term vibration).
Crafts and Commemorative Coins: Pure copper plates are used for commemorative coins and medals (high purity, easy to engrave, and long-term rust-free preservation). Brass plates are used for Buddha statues and metal paintings (golden color, suitable for fine casting).
Industrial and Mechanical Applications (Strength + Corrosion Resistance):
Marine Engineering: Aluminum bronze plates are used in ship propellers and submarine pipelines (resistance to seawater corrosion and marine biofouling); B30 cupronickel plates are used in heat exchangers for desalination equipment (heat conductivity and corrosion resistance, improving desalination efficiency);
Chemical Equipment: Cupronickel and aluminum bronze plates are used in the linings of chemical reactors and acid and alkali pipelines (resistance to sulfuric and hydrochloric acid corrosion, preventing media contamination);
Precision Machinery: Tin bronze plates are used in guide rails and gears for machine tools (excellent wear resistance and high precision retention); Beryllium bronze plates are used in explosion-proof tools (non-magnetic, spark-resistant, suitable for oil, gas, and chemical plants). Daily Necessities and Medical Devices (Antibacterial and Safety Applications):
Daily Necessities: H65 brass plate is used in bathroom fixtures (faucets and showerheads, water-resistant and antibacterial); pure copper plate is used in copper tableware (high antibacterial rate, suitable for families with children);
Medical Devices: Cupronickel plate is used in scalpels and hemostat forceps (resistant to disinfectant corrosion and no metal ion precipitation); pure copper plate is used in conductive contacts of medical devices (low resistance, ensuring signal stability).
Special Applications (Irreplaceable Functions):
Aerospace: Beryllium copper plate is used in precision springs and sensor components in aircraft (high strength and lightweight, suitable for high-altitude, low-temperature environments);
Currency and Anti-Counterfeiting: Pure copper and brass plate are used in coins (for example, the RMB 5-cent coin is made of brass, which is wear-resistant and easy to identify);
Musical Instrument Manufacturing: H62 brass plate is used in trumpet and saxophone bodies (brass has excellent acoustic properties and a bright, long-lasting tone).

IV. Copper Plate Production Process (Highlighting Copper Smelting and Rolling Characteristics)

The core of copper plate production lies in "precise control of purity/alloy composition" and "optimized processing accuracy." Compared to steel plate, the process emphasizes composition purification and plasticity control:

Raw Material Melting (Determines Copper Plate Purity and Performance):

Pure Copper Plate Melting: Electrolytic copper (purity ≥99.95%) is used as the raw material. Melted in an industrial frequency induction furnace or electric arc furnace, it is heated to 1083°C (copper melting point). Deoxidizers (such as phosphor copper) are added to remove oxygen and prevent the formation of pores. Vacuum refining or inert gas protection further reduces impurities (e.g., iron and lead content ≤ 0.005%) to ensure electrical and thermal conductivity.

Alloy Copper Plate Melting: Alloying elements such as zinc (brass), tin (tin bronze), and nickel (nickel silver) are added according to the formula and mixed evenly (ensuring a composition deviation of ≤±0.5%). For example, H62 brass requires a precise control of 62% copper and 38% zinc. The ratio of copper and copper to copper is maintained to avoid compromising strength and ductility.

Casting and Ingot Preparation:

Casting: Molten copper is poured into a mold (continuous casting machine or die casting), cooled to a solid state, and formed into a copper ingot (square billet or slab, 100-200mm thick). Continuous casting allows for automated production, resulting in more uniform ingot quality (free of shrinkage cavities and inclusions).

Ingot Treatment: After cooling, the ingot is surface-polished to remove defects such as scale and cracks to ensure quality for subsequent rolling. Rolling (hot rolling and cold rolling, which determine thickness and precision):
Hot rolling: The ingot is heated to 800-900°C (above the recrystallization temperature of copper) and rolled multiple times (3-5 passes) through a hot rolling mill to reduce the thickness to 3-100mm. During rolling, the rolling speed (1-3m/s) and the reduction (10%-20% reduction per pass) are controlled to prevent cracking. After hot rolling, the hot-rolled copper sheet is pickled (using sulfuric acid solution to remove surface oxide scale) to obtain the hot-rolled copper sheet.
Cold rolling: The hot-rolled pickled copper sheet is rolled at room temperature through a cold rolling mill (a multi-roll reversing mill) with a reduction of 5%-15% per pass, over 3-8 passes, to the target thickness of 0.1-3mm. During the cold rolling process, the sheet increases in hardness and decreases in ductility due to work hardening, requiring intermediate annealing (annealing temperature for pure copper sheet is 400-600°C, with a holding temperature of 150°C). 1-2 hours), continue rolling after recovering plasticity; after cold rolling, finish rolling can be carried out (thickness deviation ≤±0.01mm) to improve dimensional accuracy. Heat Treatment and Finishing (Optimizing Performance and Surface Condition):
Heat Treatment: Annealing (to reduce hardness and restore plasticity), solution treatment (alloy copper sheets, such as beryllium bronze, have a solution temperature of 800-850°C to increase strength), and aging (beryllium bronze has an aging temperature of 300-350°C to further increase hardness) are performed as needed.
Surface Treatment: Cold-rolled copper sheets can be polished (mechanically or chemically to achieve a mirror finish), passivated (to form a protective film to slow oxidation), and plated (such as nickel or gold plating to improve corrosion resistance and conductivity).
Finishing: The sheet is straightened to achieve flatness (deviation ≤ 0.5mm/m) and cut to a fixed size (e.g., 1000mm×2000mm, 1220mm×2440mm) using a shear. Finally, flaw detection (ultrasonic testing to detect internal defects) is performed before packaging and shipment. V. Summary
Copper sheet, with its combined advantages of high electrical and thermal conductivity, excellent workability, unique corrosion resistance, and aesthetic value, fulfills irreplaceable functions in electronics, construction, and industry. From conductive sheets that ensure low-loss operation in electronic devices, to copper curtain walls that lend a high-end aesthetic to buildings, to ship components designed to withstand the harsh marine environment, copper sheet remains a special metal material that combines both functionality and scarcity.

With technological advancements, copper sheet is evolving towards high precision (cold-rolled copper sheet with a thickness tolerance of ≤±0.005mm, suitable for microelectronic components), composite materials (copper-aluminum composite sheets and copper-steel composite sheets, balancing performance and cost), and environmental friendliness (lead-free brass sheet, RoHS compliant). In the future, it will further expand its application in emerging fields such as new energy (such as conductive components for hydrogen energy devices) and high-end chips (precision heat dissipation substrates), continuously expanding the application boundaries of high-performance metal sheet.