1. What is a PCB Via Inductance Calculator?

Definition: This calculator estimates the inductance of a via in a printed circuit board (PCB) based on its physical dimensions.

Purpose: It helps PCB designers understand and minimize via inductance which can affect high-frequency signal integrity.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( L \) — Via inductance (nanohenries)
• \( h \) — Via height or length (millimeters)
• \( r \) — Via radius (millimeters)

Explanation: The inductance increases with via height and decreases with via radius. The logarithmic relationship accounts for the geometry's effect on magnetic fields.

3. Importance of Via Inductance Calculation

Details: Via inductance can cause signal reflections, power integrity issues, and EMI problems in high-speed designs. Proper calculation helps optimize via placement and dimensions.

4. Using the Calculator

Tips: Enter the via height (PCB thickness) and via radius (half of drill diameter). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why does via inductance matter?
A: In high-frequency circuits, via inductance can create impedance discontinuities that degrade signal quality.

Q2: How can I reduce via inductance?
A: Use shorter vias (thinner PCBs), larger diameter vias, or multiple parallel vias.

Q3: What's a typical via inductance value?
A: For a standard 1.6mm PCB with 0.2mm radius via, inductance is about 1.2nH.

Q4: Does this formula account for via pads?
A: No, this is the inductance of the barrel only. Pads add additional parasitic inductance.

Q5: When is via inductance negligible?
A: For low-frequency circuits (typically below 100MHz) or very short connections.