PCB Line Width Calculator

PCB 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 Line Width Calculator?

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

Purpose: It helps PCB designers and engineers ensure proper current carrying capacity and thermal performance of their circuit board 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 amps
ΔT — Temperature rise in °C
thickness — Copper thickness in oz/ft² (1 oz/ft² = 1.37 mils)
k — Constant (0.048 for external traces, 0.024 for internal traces)

Explanation: The formula calculates the minimum trace width needed to prevent excessive temperature rise based on current, copper thickness, and trace location.

3. Importance of Proper Trace Width

Details: Correct trace width ensures:

Adequate current carrying capacity
Prevention of excessive temperature rise
Reliable PCB operation
Long-term durability

4. Using the Calculator

Tips:

Enter current in amps (typical range: 0.1-20A)
Specify acceptable temperature rise (common values: 10-20°C)
Select copper thickness (common values: 0.5-2 oz/ft²)
Choose trace location (external or internal)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between external and internal traces?
A: External traces are on outer layers with better heat dissipation (k=0.048). Internal traces are in inner layers with poorer heat dissipation (k=0.024).

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

Q3: How does copper thickness affect trace width?
A: Thicker copper allows narrower traces for the same current, as shown by the thickness exponent (-0.43) in the formula.

Q4: What if my calculated width is too narrow for manufacturing?
A: Consider increasing copper thickness or using multiple parallel traces to distribute current.

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