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About This Tool
Determine required printed circuit board copper trace widths and current-carrying capacity directly in your browser. Circuit board designers must size high-current power tracks properly to prevent Joule self-heating from exceeding dielectric glass transition temperatures (Tg) or causing thermal delamination.
This engineering tool implements the standardized empirical thermal equation defined by IPC-2152 and IPC-2221: Area (in sq mils) = (Current / [k × (TempRise^b)])^(1/c), where k is 0.048 for external surface layers (or 0.024 for internal stripline planes), b is 0.44, and c is 0.725. Dividing the resulting copper cross-sectional area by the foil thickness (such as 1.37 mils for standard 1 oz copper or 2.74 mils for 2 oz copper) determines the minimum safe trace width in mils and millimeters.
For example, routing a continuous 3.0 Amp DC current with an allowable temperature rise of 10 °C on an external layer with 1 oz copper (1.37 mils thickness) evaluates to a required conductor area of approximately 74.45 sq mils, resulting in a minimum trace width of 54.34 mils (1.38 mm).
All circuit calculations execute locally in your web browser. No PCB schematics, board stackups, or electrical load parameters leave your device.
How to Use
- 1
Enter your continuous electrical current in Amperes (A).
- 2
Specify your maximum allowable trace temperature rise above ambient (default 10 °C).
- 3
Select your copper foil weight in ounces per square foot (e.g. 1 oz = 1.37 mils).
- 4
Toggle between external microstrip and internal stripline copper layer locations.
- 5
Review the calculated minimum trace width in mils and millimeters.
Frequently Asked Questions
Why do internal PCB layers require wider traces than external layers for the same current?
External traces transfer heat directly into ambient air via convection and radiation, whereas internal layers are encased in FR-4 fiberglass, which acts as a thermal insulator (k factor drops from 0.048 to 0.024).
What is the physical thickness of 1 oz copper foil?
One ounce of copper per square foot creates an electrodeposited foil thickness of approximately 1.37 mils (0.035 mm or 35 micrometers).
Are any circuit board designs or current numbers sent to an external server?
No. The IPC-2152 mathematical models execute entirely client-side within your browser runtime.