1. What is PCB Trace Width Calculation?

The PCB trace width calculation determines the minimum width of a copper trace needed to carry a specific current while keeping the temperature rise within acceptable limits. This is crucial for PCB design and reliability.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

Where:

• \( i \) — Current in amperes (A)
• \( k \) — Constant (0.024 for inner layers, 0.048 for outer layers)
• \( \Delta T \) — Temperature rise in degrees Celsius (°C)
• \( width_{mm} \) — Calculated trace width in millimeters (mm)

Explanation: The formula accounts for the non-linear relationship between current, temperature rise, and required trace width.

3. Importance of Trace Width Calculation

Details: Proper trace width ensures the PCB can handle the required current without excessive temperature rise, preventing trace damage and ensuring long-term reliability.

4. Using the Calculator

Tips: Enter current in amperes, select appropriate k value (0.024 for inner layers, 0.048 for outer layers), and desired maximum temperature rise. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between inner and outer layer constants?
A: Outer layers (k=0.048) can dissipate heat better than inner layers (k=0.024), so they can be narrower for the same current.

Q2: What's a typical temperature rise limit?
A: 10°C is common for general purposes, but higher values (20-30°C) may be acceptable in some applications.

Q3: Does this account for trace thickness?
A: The formula assumes standard 1 oz/ft² copper (35μm thick). For other thicknesses, adjust the k value proportionally.

Q4: What about high-frequency signals?
A: This calculates for current capacity only. High-frequency signals may require different widths for impedance control.

Q5: How accurate is this calculation?
A: It provides a good estimate, but actual performance depends on PCB material, surrounding traces, and airflow.