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What is Spherical Copper Powder?
Spherical copper powder is a type of metallic copper powder, and its core feature lies in the fact that its particles present highly regular spherical or nearly spherical geometric shapes. This special morphology, which is distinct from irregularly shaped powders, endows spherical copper powder with a series of unique physical and chemical properties, making it play an indispensable role in many high-tech fields of modern industry. Its essence is to use specific physical or chemical methods (such as gas atomization, plasma atomization, reduction, etc.) to finely disperse molten copper liquid or copper compounds and condense them into spherical particles.
The Characteristics of Spherical Copper Powder
- Appearance and morphology: The spherical copper powder is light rose red in color. Under electron microscopy, the particles are regular spherical and the surface is relatively smooth.
- Particle size: The particle size range is quite wide, ranging from the nanometer level to tens of micrometers. Common particle sizes include 20nm, 100nm, 1μm, 5μm, etc.
- Density: The bulk density is generally between 4.0 and 5.0g/cm³, and the tapped density is between 5.0 and 6.0g/cm³.
- Purity and Impurities: It has a relatively high purity and low impurity content. For instance, the content of impurities such as iron, zinc, and lead is usually below several hundred ppm.
- Fluidity and sphericity: The spherical structure ensures good fluidity, low frictional resistance between particles, and is convenient for processing and filling.
- Oxidation resistance: The surface of copper powder is prone to oxidation and usually requires oxidation resistance treatment or storage in an inert gas environment.
- Chemical stability: It is stable in dry air but prone to form copper oxide (Cu₂O) in a humid environment.
- Electrical conductivity: It has excellent electrical conductivity and a low resistivity, making it suitable for use in electronic materials.
- Thermal conductivity: It has excellent thermal conductivity and can be used as a heat dissipation material.
The Application of Spherical Copper Powder
- Electronics and Microelectronics Industry (Core application fields) :
Conductive inks and pastes: They are key materials for manufacturing printed circuit boards (PCBS), flexible printed circuits (FPCS), touch screen electrodes, RFID antennas, solar cell electrodes, membrane switches, etc. High electrical conductivity, excellent printability (good fluidity, clear line edges), and low-temperature sintering activity are its advantages.
Electronic paste: It is used in thick film hybrid integrated circuits (HIC) to manufacture components such as resistors, capacitors, and conductor circuits. Spherical powder offers more stable resistance values and better printing resolution.
Chip packaging: It is widely used as a conductive filler in conductive adhesives (ECA), anisotropic conductive adhesive films (ACF), and underfills to achieve electrical interconnection and mechanical fixation between the chip and the substrate. It is also used in high thermal conductivity interface materials to quickly dissipate the heat from the chip.
Electromagnetic interference Shielding (EMI Shielding) : It is used to prepare conductive coatings, conductive foams, conductive rubbers, etc., providing efficient electromagnetic shielding protection for electronic device casings, cables, connectors, etc.
2. Powder Metallurgy
High-performance structural components: Through pressing, sintering, and sometimes supplemented by subsequent processing (impregnation, re-pressing and re-burning, forging), complex-shaped and high-performance copper-based or copper alloy (such as bronze, brass, copper-nickel alloy) parts are manufactured, such as gears, bearings, bushings, friction plates, electrical contacts, structural components, etc. Spherical powder offers high green body strength, high sintering density and excellent dimensional controllability.
Porous materials: By using pore-forming agents or controlling sintering processes, copper-based porous materials with specific porosity and pore structures can be manufactured, which are used in filtration, oil-impregnated bearings, noise reduction, capillary cores, etc.
3. Thermal Spraying and Surface Engineering
By using technologies such as plasma spraying, flame spraying and cold spraying, spherical copper powder is rapidly sprayed onto the surface of the substrate to form a dense coating with high bonding strength.
Functional coatings: Provide excellent conductive layers (such as electromagnetic shielding, grounding), heat-conducting layers (heat dissipation), wear-resistant layers, corrosion-resistant layers (especially for certain chemicals), or serve as a base bonding coating. Cold spraying is particularly suitable for preparing pure copper coatings with low oxygen content and high electrical and thermal conductivity.
4. Additive Manufacturing (3D printing)
Metal 3D printing: It is an important raw material for metal 3D printing processes such as selective laser melting (SLM), electron beam melting (EBM), and Binder Jetting. Spherical powder ensures excellent powder-spreading properties, high bulk density and uniform melting behavior, and is used to manufacture complex geometric pure copper or copper alloy parts that are difficult to process by traditional methods, such as high-efficiency heat sinks, complex flow channel mold inserts, inductive coils, customized conductive structures, etc.
5. Chemical Engineering and Catalysis
Catalysts and carriers: Spherical copper powder with high specific surface area (especially at the nanometer level) can be directly used as a catalyst (such as in certain hydrogenation and dehydrogenation reactions), or serve as an excellent carrier for precious metal catalysts. Its shape is regular, which is conducive to the diffusion of reactants and the desorption of products.
Chemical reducing agent: In specific hydrometallurgy or organic synthesis reactions, it participates in the reaction as a strong reducing agent.
6. Thermal management
Heat dissipation components: Besides its indirect application as a heat conduction filler, it is also directly used to manufacture the capillary core structure inside sintered heat pipes and Vapor chambers. The porous structure formed by sintering spherical powder has controllable porosity, pore size and excellent capillary suction force, which is the key to efficient two-phase heat transfer.
Heat dissipation substrate: Copper or copper alloy heat dissipation bases, fins, etc. prepared by powder metallurgy or 3D printing.
7. Other Fields
Lubricant additive: As an additive for solid lubricants (such as certain high-temperature greases and dry film lubricants), it takes advantage of copper’s ductility and anti-friction properties to provide lubrication and anti-wear protection under extreme working conditions.
Friction materials: Used in the formulations of friction materials for brake pads, clutches, etc., to adjust the coefficient of friction, enhance wear resistance and thermal conductivity.
Diamond tools: Used as a binder for manufacturing diamond tools for cutting, grinding and drilling.
