Is the copper thickness of aluminum-based PCBs different from other PCBs?
October 21, 2025
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Aluminum-based PCBs are widely used in LED lighting, power supplies, and automotive electronics due to their excellent heat dissipation performance. This leads to a frequently asked question: are the copper thickness specifications for aluminum-based PCBs different from standard FR-4 boards?
Standard Copper Thickness Range
FR-4 PCBs use copper thicknesses ranging from 0.5 oz/sq ft (17.5 microns) to 2 oz/sq ft (70 microns) in most applications. For high-current designs, the copper thickness can be extended to 3 oz/sq ft (105 microns) or even 6 oz/sq ft (210 microns).
In contrast, aluminum-based PCBs primarily use 1 oz/sq ft (35 microns) as the baseline copper thickness. While 0.5 oz copper is technically possible, this thickness is rarely specified for aluminum substrates. The most common copper thickness range for aluminum-based PCBs is 1 oz to 3 oz (35-105 microns), with 2 oz (70 microns) being particularly common in LED applications. For high-power applications, thicker copper layers of 4 oz to 6 oz (140-210 microns) are also available, but these represent a smaller portion of the production volume.
Why do aluminum-based PCBs use thicker copper?
The use of thicker copper layers in aluminum-based PCBs stems from their primary function as a heat dissipation solution. Aluminum substrates typically consist of three layers: a copper circuit layer, a thermally conductive dielectric layer, and an aluminum base plate. The copper layer serves to carry current and acts as a heatsink, transferring thermal energy from the components to the aluminum base plate.
Thicker copper layers provide better current carrying capacity; a 2 oz copper layer can safely handle approximately twice the current of a 1 oz copper layer before reaching its temperature limit. This increased current capacity reduces resistive losses and heat generation within the copper traces themselves. Furthermore, thicker copper layers improve heat spreading across the board surface.
Conclusion
The copper layer thickness of aluminum-based PCBs is indeed different from standard FR-4 circuit boards. Although both types of circuit boards can theoretically use similar copper weights, aluminum-based PCBs primarily utilize thicker copper layers (1-3 ounces) to optimize heat dissipation. This preference reflects the fundamental purpose of aluminum-based PCBs: to provide efficient heat dissipation in high-power applications.
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