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 temperature rise within acceptable limits.

Purpose: It helps PCB designers ensure proper current carrying capacity and prevent overheating of traces.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

Where:

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

Explanation: The formula accounts for current, allowable temperature rise, copper thickness, and whether the trace is on an external or internal layer.

3. Importance of Proper Trace Width

Details: Correct trace width prevents overheating, ensures reliable operation, and meets safety standards. 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 (external/internal). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between external and internal traces?
A: External traces (on outer layers) can dissipate heat better than internal traces, hence the different k constants.

Q2: What temperature rise should I use?
A: Common values are 10-20°C. Higher values allow narrower traces but increase operating temperature.

Q3: What are typical copper thicknesses?
A: Common values are 0.5 oz/ft² (thin), 1 oz/ft² (standard), and 2 oz/ft² (high current).

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

Q5: How do I convert mils to millimeters?
A: Multiply mils by 0.0254 (1 mil = 0.0254 mm).