PCB & Traces Formulas
PCB and trace formulas relate copper geometry to current capacity, resistance, and temperature rise. These calculators help you choose trace widths and via counts that carry current safely. They are essential for power routing and high-current board design.
PCB & Traces Formula Calculators
- Trace Current Capacity (IPC-2221) I = k × ΔT^0.44 × A^0.725
- Trace Resistance R = ρ × L / A (copper)
- Trace Voltage Drop Vdrop = I × R
- Via Current Capacity (IPC-2221) I = k × ΔT^0.44 × A^0.725
- Microstrip Impedance Z₀ ≈ (87/√(εr+1.41)) × ln(5.98h/(0.8w+t))
- Stripline Impedance Z0 = (60/√εr) × ln(4h/(0.67π×(0.8w+t)))
- Differential Pair Impedance Zdiff ≈ 2 × Z0 × (1 − 0.48 × e^(−0.96s/h))
- Near-End Crosstalk NEXT = Kb × length
- Via Inductance L = 5.08 × h × (ln(4h/d) + 1) nH
- EMI Shielding Effectiveness SE = 20 × log10(Ei / Et)
- Plane Spreading Resistance Rspread = ρ / (π × r)
- Transmission Line Propagation Delay td = length × √(LC)
- Creepage/Clearance Estimate clearance ≈ Vpeak / 500 mm
- PCB Signal Propagation Velocity vp = c / √(εr_eff)
- Thermal Via Array Resistance Rarray = Rsingle / n
- Copper Weight to Thickness t = oz × 35 µm
- Annular Ring Width AR = (Dpad − Ddrill) / 2
- PCB Trace Signal Delay td = length / vp
- Controlled Impedance Tolerance ΔZ/Z = √((Δh/h)² + (Δw/w)² + (Δεr/εr)²)
- Coplanar Waveguide Impedance Z0 = (30π/√εeff) · K(k′)/K(k)
- Signal Knee Frequency fknee = 0.5 / tr
- Transmission-Line Critical Length lcrit = tr / (2 · tpd)
- Via Stub Resonant Frequency fres = c / (4 · lstub · √εr)
- Guided Wavelength in Dielectric λg = c / (f · √εr)
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