1. What is the Polar PCB Impedance?

The Polar PCB Impedance formula calculates the characteristic impedance of a printed circuit board trace based on its dimensions and the dielectric properties of the substrate material.

2. How Does the Calculator Work?

The calculator uses the Polar formula:

Where:

• \( er \) — Relative permittivity (dimensionless)
• \( h \) — Height (mil)
• \( w \) — Width (mil)
• \( z \) — Impedance (ohm)

Explanation: The equation accounts for the relationship between trace dimensions, substrate properties, and resulting characteristic impedance.

3. Importance of Impedance Calculation

Details: Accurate impedance calculation is crucial for designing high-speed digital circuits and RF applications where signal integrity depends on proper impedance matching.

4. Using the Calculator

Tips: Enter relative permittivity (er), height (h) and width (w) in mils. All values must be valid (greater than 0).

5. Frequently Asked Questions (FAQ)

Q1: What is relative permittivity?
A: Relative permittivity (er) is a material property that affects how electric fields interact with the substrate, influencing the speed and impedance of signals.

Q2: Why use mils as the unit?
A: Mils (thousandths of an inch) are commonly used in PCB design, though the calculator could be adapted for other units if needed.

Q3: What are typical impedance values?
A: Common values are 50Ω for RF systems and 75Ω for video applications, though specific designs may require different values.

Q4: Are there limitations to this formula?
A: The accuracy depends on the specific trace geometry and may need adjustment for complex configurations or very high frequencies.

Q5: How does temperature affect the results?
A: Temperature can affect the dielectric constant of the substrate material, which may require compensation in precision applications.