PCB 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

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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 the temperature rise within acceptable limits.

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

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:

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

Explanation: The formula accounts for current carrying capacity, acceptable temperature rise, and copper thickness.

3. Importance of Proper Trace Width

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

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. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between external and internal traces?
A: External traces can dissipate heat better (higher k value) than internal traces sandwiched between layers.

Q2: What temperature rise should I use?
A: 10°C is common, but higher values (20-30°C) may be acceptable for some applications.

Q3: How does copper thickness affect trace width?
A: Thicker copper (2oz/ft²) allows narrower traces for the same current, while thinner copper requires wider traces.

Q4: What's the minimum practical trace width?
A: Most PCB manufacturers can reliably produce 5-6 mil traces, with advanced processes going down to 3 mils.

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