What is the best metal for a busbar?

In most cases, copper busbars achieve the best balance in terms of conductivity, mechanical strength, and long-term reliability.
When weight, cost, or a larger cross-sectional area margin dominates, aluminum busbars are superior.
For high-reliability or high-frequency applications, silver plating (or tin plating when on a budget) is a critical enhancement.

When selecting the "best" metal, it is essential to weigh electrical performance against mechanical, environmental, and economic factors to find the ideal solution for a specific busbar installation.

Silver has the highest conductivity of all metals, but its high cost and tendency to tarnish often preclude its use as a bulk busbar material.
Copper offers excellent conductivity, mechanical strength, and ease of installation, making it the industry standard for most busbar applications.
When space or weight is limited, aluminum is a lightweight and cost-effective alternative, but it requires a larger cross-sectional area and careful joint design to mitigate oxidation and thermal expansion issues.

Surface treatments (most commonly silver or tin plating) are often used on copper or aluminum busbars to stabilize contact resistance and extend service life in harsh environments.

Common Busbar Materials

Busbars are typically made from copper, aluminum, or brass, with each material selected based on a balance of electrical, mechanical, and economic factors. Copper busbars dominate in switchgear, distribution panels, and battery packs due to their excellent conductivity and mechanical strength. Although aluminum busbars have lower conductivity per cross-sectional area, they can significantly reduce weight and cost, making them attractive for large distribution systems and applications with strict weight constraints. Brass and steel are rarely used due to their significantly lower conductivity, making them unsuitable for high-current applications.

Conductivity vs. IACS Ratings Comparison

Material	Conductivity (MS/m)	Conductivity (S/m)	IACS Rating (%)	Features
Silver	63.0	6.30 × 10⁷	106%	Highest conductivity, mainly used in high-end applications
Copper	59.6	5.96 × 10⁷	100% (Standard)	Benchmark for electrical conductors
Aluminum	35.0	3.50 × 10⁷	61%	Low density, conductivity per unit mass is about twice that of copper

Mechanical and Thermal Properties Comparison

Material	Density	Modulus of Elasticity	Mechanical Strength	Coefficient of Thermal Expansion	Creep Resistance	Special Considerations
Copper	High	High	High	Medium	Good	Requires less support, more compact structure
Aluminum	Low	Medium	Medium	High	Prone to creep	Requires special connectors and torque control
-	-	-	-	-	-	For high frequencies, consider skin effect and heat dissipation design

Corrosion, Oxidation and Surface Treatment

Material	Oxidation Characteristics	Surface Treatment Options	Features	Precautions
Aluminum	Easily oxidized	Anti-oxidation compounds, coatings	Oxide layer is stable but has poor conductivity	Reduce contact resistance, prevent joint loosening
Copper	Stable	Silver plating, tin plating	Low contact resistance, good corrosion resistance	Coating still recommended in corrosive environments
Silver Plating	Excellent	-	Gold standard, excellent thermal stability, long lifespan	May lose luster but performance remains
Tin Plating	Good	-	Good solderability, economical and practical	Slightly lower performance than silver but cost-effective

Cost, Availability and Practicality

Material	Material Cost	Conductivity per Unit Mass	Space Requirement	Application Scenarios	Economic Efficiency
Aluminum	About 1/3 that of copper	Twice that of copper	Advantageous when space is ample	Large-scale busbars, cost-sensitive scenarios	Excellent
Copper	High	Standard	Preferred in compact designs	Widely used in industrial and commercial applications	Strong overall performance
Silver/Gold	Extremely high	Slightly better than copper	Usable even when space is not a concern	Aerospace, satellites, laboratories	Very poor (only for high-end use)