Introduction to PCB Current Calculator
A PCB current calculator is an essential tool for electronics engineers and designers who work with printed circuit boards (PCBs). It helps calculate the maximum current carrying capacity of PCB traces based on various factors such as trace width, thickness, temperature rise, and ambient temperature. Accurately determining the current carrying capacity is crucial to ensure the reliability and longevity of PCBs.
In this article, we will dive deep into the concept of PCB current calculators, their importance, and how to use them effectively. We will also discuss the latest advancements in PCB current calculation techniques and tools.
Why Is PCB Current Calculation Important?
PCB current calculation is important for several reasons:

Ensuring reliability: By accurately calculating the current carrying capacity of PCB traces, designers can ensure that the traces can handle the expected current without overheating or failing. This increases the overall reliability of the PCB and the device it is used in.

Preventing damage: Overloaded PCB traces can generate excessive heat, which can damage components, cause short circuits, or even start a fire. Accurate current calculation helps prevent such damage by ensuring that traces are designed to handle the expected current.

Optimizing PCB design: PCB current calculation allows designers to optimize the PCB layout by determining the appropriate trace widths for different current requirements. This helps minimize the PCB size, reduce manufacturing costs, and improve overall performance.

Meeting industry standards: Many industries have specific standards and regulations regarding PCB design and current carrying capacity. Using a PCB current calculator ensures that the designed PCB meets these standards and passes the required certifications.
Factors Affecting PCB Current Carrying Capacity
Several factors influence the current carrying capacity of a PCB trace. Understanding these factors is essential for accurate current calculation.
Trace Width
Trace width is one of the most significant factors affecting current carrying capacity. Wider traces can carry more current than narrower traces. The relationship between trace width and current carrying capacity is not linear, and it depends on other factors such as thickness and temperature rise.
Trace Width (mm)  Current Carrying Capacity (A) 

0.5  1.0 
1.0  2.5 
1.5  4.0 
2.0  6.0 
Note: The values in the table are for illustrative purposes only and may vary based on other factors.
Trace Thickness
Trace thickness also plays a role in determining the current carrying capacity. Thicker traces can carry more current than thinner traces. PCB manufacturers often specify the copper weight in ounces per square foot (oz/ft²), which represents the thickness of the copper layer.
Copper Weight (oz/ft²)  Thickness (mm) 

0.5  0.017 
1.0  0.034 
2.0  0.068 
Temperature Rise
The temperature rise of a PCB trace is another critical factor in current calculation. As current flows through a trace, it generates heat, causing the temperature to rise. The maximum allowable temperature rise depends on the PCB material, ambient temperature, and other factors.
Designers must ensure that the temperature rise of a trace does not exceed the maximum allowable limit to prevent damage and ensure reliability. The temperature rise can be calculated using the following formula:
ΔT = (I² × R × L) / (k × A)
Where:
– ΔT is the temperature rise in °C
– I is the current in A
– R is the electrical resistance of the trace in Ω/m
– L is the length of the trace in m
– k is the thermal conductivity of the PCB material in W/(m·K)
– A is the crosssectional area of the trace in m²
Ambient Temperature
The ambient temperature is the temperature of the environment in which the PCB operates. It affects the current carrying capacity because it determines the maximum allowable temperature rise. In hightemperature environments, the maximum allowable temperature rise is lower, reducing the current carrying capacity.
Designers must consider the worstcase ambient temperature when calculating the current carrying capacity to ensure reliable operation under all conditions.
PCB Current Calculator Tools
Several tools are available for calculating PCB current carrying capacity. These tools range from simple online calculators to advanced software packages that integrate with PCB design software.
Online PCB Current Calculators
Online PCB current calculators are webbased tools that allow users to quickly calculate the current carrying capacity by entering the trace width, thickness, and other parameters. These calculators are convenient and easy to use, making them suitable for quick estimations and preliminary designs.
Some popular online PCB current calculators include:
 Advanced Circuits PCB Trace Width Calculator
 EEWeb PCB Trace Width Calculator
 Saturn PCB Toolkit Current Carrying Capacity Calculator
PCB Design Software Integrated Tools
Many PCB design software packages include integrated tools for current calculation. These tools are more advanced than online calculators and offer additional features such as automatic trace width optimization and thermal analysis.
Examples of PCB design software with integrated current calculation tools include:
 Altium Designer
 Cadence OrCAD
 Mentor Graphics PADS
 Zuken CR8000
These tools streamline the PCB design process by allowing designers to calculate current carrying capacity and optimize trace widths directly within the design environment.
Best Practices for PCB Current Calculation
To ensure accurate and reliable PCB current calculation, follow these best practices:

Use uptodate standards: Refer to the latest industry standards, such as IPC2152, for guidelines on current carrying capacity and PCB design.

Consider worstcase scenarios: When calculating current carrying capacity, consider the worstcase scenarios for ambient temperature, current load, and other factors to ensure reliable operation under all conditions.

Verify calculations: Always verify the current calculations using multiple methods, such as hand calculations, online calculators, and software tools, to minimize the risk of errors.

Allow for safety margins: Include appropriate safety margins in the current calculations to account for variations in manufacturing processes, material properties, and operating conditions.

Collaborate with manufacturers: Work closely with PCB manufacturers to ensure that the designed traces meet their specifications and capabilities.
Frequently Asked Questions (FAQ)

What is the difference between internal and external PCB traces?
Internal PCB traces are located within the inner layers of a multilayer PCB, while external traces are on the outer layers. External traces can dissipate heat more easily, allowing for higher current carrying capacity compared to internal traces of the same width and thickness. 
How does the PCB material affect current carrying capacity?
The PCB material’s thermal conductivity and dielectric properties affect the current carrying capacity. Materials with higher thermal conductivity, such as aluminum or copperbased substrates, can dissipate heat more effectively, allowing for higher current carrying capacity. 
Can I use a PCB current calculator for flexible PCBs?
Yes, PCB current calculators can be used for flexible PCBs. However, it is essential to consider the specific properties of flexible materials, such as copper thickness and thermal conductivity, which may differ from rigid PCBs. 
What is the impact of vias on current carrying capacity?
Vias can affect the current carrying capacity of a PCB trace by adding resistance and creating heatgeneration points. Designers must consider the size, number, and placement of vias when calculating current carrying capacity. 
How often should I update my PCB current calculation tools and methods?
It is recommended to update PCB current calculation tools and methods regularly to ensure compliance with the latest industry standards and best practices. Staying uptodate allows designers to take advantage of new technologies and materials that can improve PCB performance and reliability.
Conclusion
PCB current calculators are indispensable tools for electronics engineers and designers working with printed circuit boards. They help ensure the reliability, performance, and longevity of PCBs by accurately determining the current carrying capacity of traces.
To use PCB current calculators effectively, designers must understand the factors affecting current carrying capacity, such as trace width, thickness, temperature rise, and ambient temperature. They should also follow best practices, including using uptodate standards, considering worstcase scenarios, verifying calculations, allowing for safety margins, and collaborating with manufacturers.
By mastering the use of PCB current calculators and staying informed about the latest advancements in PCB design tools and techniques, electronics engineers and designers can create highquality, reliable PCBs that meet the everincreasing demands of modern electronic devices.
No responses yet