Tools/Thermal Relief Calculator

Thermal Relief Calculator

Design thermal relief patterns for optimal soldering

Thermal Relief Parameters

Thermal Relief Pattern (Top View)

Pad Diameter (mil)

Drill Diameter (mil)

Spoke Width (mil)

Number of Spokes

Copper Weight (oz)

Expected Current (A)

Analysis Results

Good balance - Easy soldering with adequate current capacity

Opening Ratio

74.5%

Current Capacity

3.5 A

Annular Ring

10.0 mil

Resistance

0.120 mΩ

Voltage Drop

0.120 mV

Gap Width

29.3 mil

Power Loss

0.120 mW

Thermal Relief Design Guidelines

For Better Soldering

• Use 4 spokes minimum for symmetry
• Spoke width: 8-12 mil typical
• Opening ratio: 50-70%
• Gap width: >8 mil for manufacturability
• Consider 2 spokes for hand soldering

For High Current

• Use wider spokes: 15-20+ mil
• Increase spoke count to 6 or 8
• Direct connect for very high current
• Consider thicker copper (2+ oz)
• Multiple vias for power distribution

Thermal reliefs isolate pads from copper planes, preventing heat sink effects during soldering. Without thermal relief, large planes can absorb heat too quickly for proper solder joints.

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