PCB Power Trace Width Calculator

Trace Width Formula:

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

Current (I):

amps

Temperature Rise (ΔT):

°C

Copper Thickness:

oz/ft²

Trace Location:

Trace Width: mils

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a PCB Power Trace Width Calculator?

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

Purpose: It helps PCB designers ensure proper current handling capacity while maintaining safe operating temperatures.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

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

Where:

\( \text{Width} \) — Trace width in mils (1 mil = 0.001 inch)
\( I \) — Current in amps
\( \Delta T \) — Temperature rise above ambient in °C
\( \text{thickness} \) — Copper weight in oz/ft²
\( k \) — Constant (0.048 for external, 0.024 for internal traces)

Explanation: The formula accounts for current, temperature rise, copper thickness, and trace location to determine minimum width.

3. Importance of Proper Trace Width

Details: Correct trace width prevents overheating, ensures reliable operation, and maintains signal integrity in PCB designs.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's a typical temperature rise?
A: 10°C is common, but higher values (20-30°C) may be acceptable depending on application.

Q2: How does copper thickness affect width?
A: Thicker copper allows narrower traces for the same current, as shown by the inverse relationship in the formula.

Q3: Why different constants for internal/external traces?
A: External traces dissipate heat better (higher k), while internal traces have poorer heat dissipation (lower k).

Q4: What's the minimum practical trace width?
A: Most PCB manufacturers can handle 5-6 mil widths, but check with your fabricator for capabilities.

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