When it comes to printed circuit boards (PCBs), many designers focus on layer count, material type, and surface finish. However, there’s one critical factor that can make or break your board’s reliability: PCB copper thickness. It plays a vital role in determining current-carrying capacity, thermal performance, and overall durability of the board.
In this article, we’ll break down what PCB copper thickness means, how it’s measured, standard copper weight values, and how to choose the right thickness for your specific application.
What Is PCB Copper Thickness?
PCB copper thickness refers to the thickness of the copper layer applied to the surface and inner layers of a printed circuit board. It is usually measured in ounces per square foot (oz/ft²) or in microns (μm) or mils.
- 1 oz/ft² of copper equals approximately 35 μm or 4 mils in thickness.
- This means that one ounce of copper spread evenly over a square foot of area results in a 35-micron thick layer.
Standard Copper Thickness Values
Here are the most common copper thickness values used in the industry:
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Why PCB Copper Thickness Matters
Choosing the right copper thickness affects several key factors:
- Current Carrying Capacity
Thicker copper allows more current to flow without overheating. This is critical for power electronics, motor control boards, and high-load systems.
- Thermal Management
More copper helps dissipate heat better, especially in high-power circuits or boards without active cooling.
- Voltage Drop and Resistance
Thicker copper reduces the resistance of traces, resulting in lower voltage drop and more efficient power distribution.
- Mechanical Strength
Heavier copper improves the mechanical durability of vias and pads, especially important in high-vibration environments.
Applications of Thick Copper PCBs
- Power Supply Boards
- Automotive Electronics
- LED Drivers
- Solar Inverters
- Industrial Control Systems
How to Choose the Right Copper Thickness
Here are a few considerations:
- For signal circuits (low power): 1 oz copper is typically sufficient.
- For moderate power circuits (up to 5A): 1–2 oz may be required.
- For power circuits (above 10A): 2–4 oz or more depending on the trace width and thermal needs.
- Use IPC-2221 standard to calculate minimum trace width based on current and copper thickness.
Pro tip: Always consult with your PCB manufacturer early, as thicker copper may affect etching tolerances, layer stack-up, and cost.
Conclusion
PCB copper thickness is more than just a number—it’s a key parameter that affects the performance, safety, and longevity of your electronics. Whether you’re building a compact IoT device or a high-current power board, understanding and selecting the right copper thickness is essential.
Need help selecting the right copper thickness for your next project? Contact us for expert PCB design and manufacturing support.