PCB Track Width Calculator

Track Width Formula:

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

Current (I):

amps

Temperature Rise (ΔT):

°C

Copper Thickness:

oz/ft²

Layer Type:

Track Width (mils):

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1. What is a PCB Track Width Calculator?

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

Purpose: It helps PCB designers ensure proper current carrying capacity while minimizing board space and heat generation.

2. How Does the Calculator Work?

The calculator uses the IPC-2221 formula:

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

Where:

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

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

3. Importance of Proper Track Width

Details: Correct trace width prevents overheating, ensures reliable operation, and meets safety standards. Too narrow traces can overheat, 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 layer type. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical temperature rise value?
A: 10°C is common for general applications, but higher values (20-30°C) may be acceptable for some designs.

Q2: How does copper thickness affect the result?
A: Thicker copper (e.g., 2 oz/ft²) allows narrower traces for the same current, while thinner copper requires wider traces.

Q3: Why different constants for internal/external layers?
A: External layers dissipate heat better (higher k value) due to exposure to air, allowing slightly narrower traces.

Q4: What if my trace needs to carry high current?
A: Consider using multiple parallel traces, thicker copper, or adding solder to increase current capacity.

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