1. What is Via Resistance?

Via resistance refers to the electrical resistance of a plated through-hole (via) in a printed circuit board (PCB). It's determined by the via's dimensions and the resistivity of the plating material (typically copper).

2. How Does the Calculator Work?

The calculator uses the via resistance formula:

Where:

• \( R \) — Via resistance (Ω)
• \( \rho \) — Resistivity of the material (Ω·m)
• \( L \) — Length of the via (m)
• \( D \) — Diameter of the via (m)

Explanation: The resistance increases with higher resistivity and longer vias, and decreases with larger via diameters.

3. Importance of Via Resistance Calculation

Details: Calculating via resistance is crucial for high-speed and high-frequency PCB designs where even small resistances can affect signal integrity and power distribution.

4. Using the Calculator

Tips: Enter resistivity in Ω·m (1.68×10⁻⁸ for copper), length and diameter in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical resistivity of copper?
A: Pure copper at 20°C has ρ ≈ 1.68×10⁻⁸ Ω·m. PCB plating may have slightly higher resistivity due to impurities.

Q2: How does via resistance affect PCB design?
A: High via resistance can cause voltage drops, signal degradation, and heating in power distribution networks.

Q3: What's a typical via diameter?
A: Common via diameters range from 0.2mm to 0.5mm (0.0002m to 0.0005m).

Q4: Does this account for the annular ring?
A: No, this calculates resistance of the barrel only. Contact resistance at pads is additional.

Q5: How to reduce via resistance?
A: Use larger diameter vias, shorter board thickness, or multiple parallel vias for critical connections.