Calculate Trace Width PCB

PCB Trace Width Equation:

\[ W = \frac{(I / (k \times \Delta T^{0.44}))^{1/0.725}}{Thick} \]

Current (I):

amps

Temperature Rise (ΔT):

°C

Copper Thickness:

mils

k Value:

unitless

Trace Width (W):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the PCB Trace Width Equation?

The PCB trace width equation calculates the minimum width required for a copper trace on a printed circuit board to carry a specified current without exceeding a given temperature rise. This is crucial for reliable PCB design and preventing overheating.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 standard equation:

\[ W = \frac{(I / (k \times \Delta T^{0.44}))^{1/0.725}}{Thick} \]

Where:

\( W \) — Trace width (mils)
\( I \) — Current (amps)
\( k \) — 0.048 (for external traces) or 0.024 (for internal traces)
\( \Delta T \) — Temperature rise (°C)
\( Thick \) — Copper thickness (mils, typically 1 for 1 oz copper)

Explanation: The equation accounts for the relationship between current, temperature rise, and trace cross-sectional area (width × thickness).

3. Importance of Proper Trace Width

Details: Proper trace width calculation prevents overheating, voltage drops, and potential board failure. It's essential for power integrity and reliability in PCB design.

4. Using the Calculator

Tips: Enter current in amps, temperature rise in °C, copper thickness in mils (1 for 1 oz copper), and k value (0.048 for external traces). All values must be positive numbers.

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). Internal traces are between layers with poorer heat dissipation (k=0.024).

Q2: What's a typical temperature rise limit?
A: Common limits are 10°C for general designs, 20°C for most applications, and up to 30°C for high-current designs.

Q3: How does copper thickness affect trace width?
A: Thicker copper (higher oz) allows narrower traces for the same current, as cross-sectional area increases.

Q4: Are there limitations to this equation?
A: It doesn't account for adjacent traces, board material, or airflow. For complex cases, use PCB thermal simulation tools.

Q5: What's the minimum practical trace width?
A: Typically 5-6 mils for most manufacturers, though advanced PCBs can go down to 3 mils or less.