Via Current Calculator
Calculate PCB via current carrying capacity based on size and plating thickness.
Finished hole diameter
Typical: 0.8-1.0 mil
Via barrel length
Common Via Sizes (1 mil plating, 10°C rise)
| Via Type | Drill | Finish Ø | Current (1 via) |
|---|---|---|---|
| Microvia | 4 mil | ~6 mil | ~0.3 A |
| Small | 8 mil | ~10 mil | ~0.5 A |
| Standard | 12 mil | ~14 mil | ~0.7 A |
| Power | 20 mil | ~22 mil | ~1.0 A |
| Large | 30 mil | ~32 mil | ~1.4 A |
How It Works
PCB vias are plated holes that connect traces between layers. The current capacity depends on:
- Via Diameter: Larger vias have more plating surface area
- Plating Thickness: Standard is 0.8-1.0 mil (20-25 μm)
- Board Thickness: Longer vias have higher resistance
- Temperature Rise: Higher allowed rise means more current
Design Guidelines
High Current Vias
- Use multiple vias in parallel for power rails
- Place vias close together (thermal coupling helps)
- Consider via-in-pad for tight spaces
- Use larger pads for better heat spreading
Thermal Vias
- Filled vias provide better thermal transfer
- Use arrays under thermal pads
- Connect to internal copper planes
- Typical spacing: 1.0-1.2mm grid
Frequently Asked Questions
How many vias do I need for 5A?
For a standard 12 mil via with 1 mil plating, you'd need approximately 7-8 vias for 5A with a 10°C temperature rise. Always add margin and distribute vias across the current path.
Should I fill power vias?
Filled vias (with copper or conductive epoxy) provide better current capacity and thermal performance. However, they add cost. For most applications, standard plated vias with proper sizing work well.
What's the minimum via size?
Standard PCB fabs support 8-10 mil drill minimum. HDI boards can go down to 4 mil laser-drilled microvias. Smaller vias cost more and have lower current capacity.