What is difference in electrical conductivity between copper and aluminum die castings?
The electrical conductivity of die-cast components is a critical parameter for applications in electronics, electrical transmission, and electromagnetic devices. While both copper and aluminum are conductive metals, there is a significant and fundamental difference in their performance. Copper die castings possess substantially higher electrical conductivity than aluminum die castings, making them the superior choice for applications where maximizing electrical efficiency is paramount.
Quantitative Conductivity Comparison
The specific difference in conductivity is most clearly understood through standardized measurements and a direct comparison of the alloys commonly used in die casting.
The International Annealed Copper Standard (IACS): Conductivity is often expressed as a percentage of the IACS, where 100% IACS represents the conductivity of annealed, pure copper at 20°C.
Copper Alloy Performance: Pure copper serves as the benchmark, but die-casting alloys incorporate additional elements to enhance castability and strength. A common and highly conductive die-cast alloy like C18200 Chromium Copper can achieve conductivities in the range of 80-85% IACS. Even more castable alloys like Free-Cutting Brass C85700 still typically offer conductivities around 25-30% IACS.
Aluminum Alloy Performance: Aluminum alloys, by their nature, have lower conductivity. A standard die-casting alloy like A380 Aluminum Alloy has a typical conductivity of approximately 20-23% IACS. Alloys with higher purity, such as those used for Aluminum Die Casting of conductive components, can reach higher values; for instance, a high-purity alloy like A360 Aluminum Alloy may achieve up to 30-35% IACS.
Direct Comparison Table:
Material | Typical Conductivity (% IACS) | Key Characteristic |
|---|---|---|
Pure Copper (Reference) | 100% | International Standard |
Die-Cast Copper Alloy (e.g., C18200) | 80-85% | Excellent for high-efficiency electrical components |
Die-Cast Brass Alloy (e.g., C85700) | 25-30% | Good conductivity with superior castability and strength |
Die-Cast Aluminum Alloy (e.g., A380) | 20-23% | The most common, balancing castability and properties |
High-Purity Die-Cast Aluminum (e.g., A360) | 30-35% | The best conductivity achievable for typical aluminum HPDC |
Material Selection and Trade-Offs
The choice between copper and aluminum for a conductive die-cast part involves balancing electrical needs with other critical factors.
When Copper is Essential: Copper die casting is selected for applications where minimal electrical loss is non-negotiable. This includes components like busbars, high-power electrical connectors, and parts for electric vehicle power systems. The inherent Copper Die Casting process leverages this high conductivity but presents challenges in higher material cost and greater difficulty in casting complex shapes compared to aluminum.
The Aluminum Advantage: Aluminum is chosen when a favorable combination of conductivity, lightweight properties, and cost-effectiveness is required. For many applications, such as enclosures for Huawei Custom Aluminum Data Base Shell Cover or frames for Custom GPU Frame, aluminum provides sufficient conductivity for grounding or shielding while offering significant weight savings. Its excellent castability also allows for more complex and thinner-walled geometries.
Impact of Manufacturing and Post-Processing
The final conductivity of a die-cast part is not solely determined by the base alloy.
The Role of Porosity: Internal porosity, an inherent characteristic of the High Pressure Die Casting process, can disrupt the continuous metallic path for electrons, thereby reducing the overall measured conductivity of the component.
Surface Treatment Effects: Many conductive components require surface finishes to enhance corrosion resistance or improve solderability. Plating with tin, silver, or nickel will alter the surface conductivity of the material. Processes like Die Castings Anodizing create a non-conductive oxide layer on aluminum and are therefore unsuitable for surfaces requiring electrical contact.
Industry Application Examples
The conductivity difference directly influences material selection across various sectors.
Automotive and E-Mobility: In electric vehicles, high-efficiency copper alloys are often specified for critical components within the battery pack and traction motor due to their superior conductivity, despite the weight penalty. Our work as a Volkswagen Supplier involves precision casting, where material properties are meticulously matched to the demands of the application.
Consumer Electronics and Electrical Hardware: Aluminum is predominantly used for housings and structural components in devices like Apple Bluetooth Wireless Earphone Hinge, where its lightweight and adequate conductivity are ideal. For internal conductive paths or contacts, copper alloys or other manufacturing methods are typically employed.
Power Tools and Industrial Equipment: Brands like Bosch Power Tools may utilize aluminum for motor housings to manage heat and weight, while copper is reserved for the commutators and windings within the motor itself where the highest conductivity is essential for performance.
