Online PCB Trace Width Calculator

PCB Trace Width Formula:

\[ \text{Width} = \left[ \frac{I}{k \times \Delta T^{0.44}} \right]^{0.725} \times \text{thickness}^{-0.43} \]

Current (I):

amps

Temperature Rise (ΔT):

°C

Copper Thickness:

oz/ft²

Trace Location:

Trace Width:

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1. What is a PCB Trace Width Calculator?

Definition: This calculator determines the minimum width of a PCB trace needed to carry a specified current while keeping the temperature rise within acceptable limits.

Purpose: It helps PCB designers ensure proper current carrying capacity and prevent overheating in printed circuit boards.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

\[ \text{Width} = \left[ \frac{I}{k \times \Delta T^{0.44}} \right]^{0.725} \times \text{thickness}^{-0.43} \]

Where:

\( \text{Width} \) — Trace width (mils)
\( I \) — Current (amps)
\( \Delta T \) — Temperature rise (°C)
\( \text{thickness} \) — Copper thickness (oz/ft²)
\( k \) — Constant (0.024 for internal, 0.048 for external traces)

Explanation: The formula calculates the minimum trace width needed to carry a given current while limiting temperature rise, accounting for copper thickness and trace location.

3. Importance of Proper Trace Width

Details: Correct trace width prevents overheating, voltage drops, and ensures reliable circuit operation. Too narrow traces can overheat and fail, while too wide traces waste board space.

4. Using the Calculator

Tips: Enter the current in amps, desired temperature rise (default 10°C), copper thickness (default 1 oz/ft²), and select trace location (internal or external).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between internal and external traces?
A: External traces are on outer layers and can dissipate heat better (k=0.048), while internal traces are between layers with poorer heat dissipation (k=0.024).

Q2: What's a typical temperature rise value?
A: 10°C is common, but higher values (20-30°C) may be used for high-current applications if the design allows.

Q3: What copper thickness should I use?
A: Standard PCBs use 1 oz/ft² (35µm), but high-current designs may use 2 oz/ft² or more.

Q4: Does this account for high-frequency effects?
A: No, this is for DC/low-frequency currents only. High-frequency designs require additional considerations.

Q5: What if my calculated width is too narrow for manufacturing?
A: Use the minimum manufacturable width and consider increasing copper thickness or using multiple parallel traces.