PCB Trace Resistance Calculator

PCB Trace Resistance Formula:

\[ R = \frac{\rho \times L}{W \times T} \]

Resistivity (ρ):

Ω·m

Length (L):

Width (W):

Thickness (T):

Resistance (R):

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1. What is PCB Trace Resistance?

PCB trace resistance refers to the electrical resistance of copper traces on printed circuit boards. It's a critical parameter in PCB design that affects signal integrity, power distribution, and thermal management in electronic circuits.

2. How Does the Calculator Work?

The calculator uses the PCB trace resistance formula:

\[ R = \frac{\rho \times L}{W \times T} \]

Where:

\( R \) — Resistance in ohms (Ω)
\( \rho \) — Resistivity of copper (1.68×10⁻⁸ Ω·m)
\( L \) — Length of the trace in meters (m)
\( W \) — Width of the trace in meters (m)
\( T \) — Thickness of the trace in meters (m)

Explanation: The formula calculates resistance based on the material's resistivity and the cross-sectional area (width × thickness) of the trace, with resistance increasing proportionally with length.

3. Importance of Trace Resistance Calculation

Details: Accurate trace resistance calculation is essential for proper PCB design, ensuring adequate current carrying capacity, minimizing voltage drops, preventing excessive heating, and maintaining signal quality in high-speed circuits.

4. Using the Calculator

Tips: Enter resistivity in Ω·m (default is copper: 1.68×10⁻⁸), length in meters, width in meters, and thickness in meters. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical resistivity of copper?
A: Pure copper has a resistivity of approximately 1.68×10⁻⁸ Ω·m at 20°C. This value increases with temperature.

Q2: How does temperature affect trace resistance?
A: Copper resistance increases by about 0.393% per °C temperature rise. For precise calculations, temperature coefficients should be considered.

Q3: What are common PCB copper thicknesses?
A: Common thicknesses include 0.5 oz (17.5 μm), 1 oz (35 μm), and 2 oz (70 μm) copper. 1 oz/ft² is the most common standard.

Q4: Why is trace resistance important in power distribution?
A: High resistance traces cause voltage drops, power loss as heat, and can lead to insufficient voltage at components, affecting circuit performance.

Q5: How can I reduce trace resistance?
A: Use wider traces, thicker copper, shorter traces, or multiple parallel traces. For critical applications, consider using heavier copper weights or adding solder to increase cross-sectional area.