PCB Trace Width vs Current Calculator

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 (mils):

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1. What is PCB Trace Width vs Current Calculator?

Definition: This calculator determines the minimum width of a PCB trace needed to safely carry a specified current without exceeding a given temperature rise.

Purpose: It helps PCB designers ensure proper trace sizing to prevent overheating and maintain reliable circuit operation.

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 (0.048 for external, 0.024 for internal traces)

Explanation: The formula calculates the minimum trace width needed to safely carry the specified current while limiting temperature rise.

3. Importance of Proper Trace Width

Details: Correct trace width prevents overheating, voltage drops, and potential PCB failure. It's critical for power integrity and reliability.

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.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between external and internal traces?
A: External traces can dissipate heat better (higher k value) than internal traces sandwiched between layers.

Q2: What's a typical temperature rise limit?
A: 10°C is common, but higher values (20-30°C) may be acceptable depending on application.

Q3: How does copper thickness affect trace width?
A: Thicker copper allows narrower traces for the same current, as shown by the thickness exponent.

Q4: What are mils in PCB measurements?
A: 1 mil = 0.001 inch. Most PCB design tools use mils as the default unit for trace width.

Q5: Does this account for high-frequency effects?
A: No, this is for DC/low-frequency currents. High-frequency designs need additional considerations.