Calculate Trace Width For Current

PCB Trace Width Formula:

\[ Width = \left( \frac{Current}{k \times TempRise} \right)^{\frac{1}{m}} \]

Current (I):

Constant (k):

Temperature Rise (ΔT):

°C

Exponent (m):

Trace Width:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the PCB Trace Width Calculation?

The PCB trace width calculation determines the appropriate width for copper traces on printed circuit boards based on current carrying capacity, temperature rise, and material properties. It ensures reliable operation and prevents overheating.

2. How Does the Calculator Work?

The calculator uses the trace width formula:

\[ Width = \left( \frac{Current}{k \times TempRise} \right)^{\frac{1}{m}} \]

Where:

\( Current \) — Current flowing through the trace (Amperes)
\( k \) — Material constant (typically 0.024 for outer layers)
\( TempRise \) — Allowable temperature rise (°C)
\( m \) — Exponent (typically 0.44 for outer layers)

Explanation: The equation calculates the minimum trace width needed to carry a specific current while limiting temperature rise to an acceptable level.

3. Importance of Proper Trace Width

Details: Correct trace width calculation is essential for PCB reliability, preventing overheating, voltage drops, and ensuring the circuit operates within safe temperature limits.

4. Using the Calculator

Tips: Enter current in amperes, appropriate k constant for your PCB material, desired maximum temperature rise, and the exponent value. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for k and m?
A: For outer layers: k = 0.024, m = 0.44. For inner layers: k = 0.048, m = 0.725. These may vary based on specific PCB materials.

Q2: What temperature rise is acceptable?
A: Typically 10-20°C is acceptable for most applications. Higher temperature rises may be acceptable in specific cases but reduce safety margins.

Q3: Does trace thickness affect the calculation?
A: Yes, the formula assumes standard 1 oz/ft² copper thickness (35μm). For different thicknesses, adjustments are needed.

Q4: Are there other factors to consider?
A: Yes, ambient temperature, airflow, proximity to other heat sources, and PCB material thermal conductivity all affect actual performance.

Q5: Should I add safety margins?
A: Yes, it's recommended to add 10-20% safety margin to the calculated width, especially for high-reliability applications.