Via current
What one plated through-hole via can carry, how many to put in parallel for a current, and their resistance.
Inputs
Use a dot or a comma for decimals.
Results
- Current of one via
- 1.9A
- Vias in parallel
- 3
- Copper cross-section of the barrel
- 0.0255mm²
- Resistance of one via at 20 °C
- 1.081mΩ
- Resistance of one via at working temperature
- 1.144mΩ
- All the vias in parallel, at working temperature
- 0.381mΩ
- Voltage drop at the target current
- 1.91mV
A finished hole is the hole after plating. Ask the factory for the copper thickness it plates in holes; the figure you type is your assumption.
The formula
A = π × t × (d + t) I = 0.048 × ΔT^0.44 × A^0.725 R = ρ × h ÷ A
d is the finished hole diameter, t the plating thickness and h the board thickness; A is the copper ring of the barrel. The current uses the IPC-2221 track formula (outer-layer constant 0.048, A in square mils, ΔT in °C) on that ring. The count is the target current divided by the current of one via, rounded up.
Where the formula holds
IPC-2221 gives no formula for vias; applying its track formula to the barrel is a common approximation, not part of the standard. It assumes the vias share the current equally and do not heat each other, so space them a few millimetres apart and keep margin. The page refuses holes outside 0.1 to 1 mm, plating outside 10 to 50 µm, boards outside 0.2 to 3.2 mm and a rise outside 10 to 100 °C.
Source: IPC-2221 track formula applied to the barrel cross-section. Calculated in your browser. Nothing is sent to a server.