Calculadora de Impedância de Trilha

Impedância microstrip e stripline

Operating Mode

Required Parameters

Trace width

Copper thickness

Dielectric height

Relative dielectric constant

Waiting for input data...

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Quick Answer

Microstrip impedance depends heavily on the trace width, dielectric height (prepreg/core thickness), and the substrate's dielectric constant (Er).

Documentation

Calculadora de Impedancia de Trilha

Calcule a impedancia caracteristica de trilhas microstrip e stripline em PCB para projetos digitais de alta velocidade e RF.

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Design Notes

This calculator uses IPC-2141 analytic approximations, which are excellent for sub-GHz designs. However, for precise multi-gigabit routing (PCIe, USB 3.0, DDR4), you must rely on 2D/3D field solvers (like Si9000 or built-in Altium/KiCad solvers) and work directly with your PCB manufacturer's controlled-impedance stackup. Prepreg thickness often shrinks during pressing; always let the fab house tweak your final trace width.

Common Mistakes

1
Not referencing a solid, continuous ground plane directly beneath the trace (routing over splits causes huge impedance discontinuities).
2
Ignoring the solder mask effect: Solder mask slightly lowers the impedance of an external microstrip by 2-3 ohms.
3
Using generic FR4 formulas for precise 5GHz+ RF feeds without accounting for the varying Er of woven glass weaves.

Engineering Handbox

1. Apply Microstrip: Z0 = (87 / √(4.4 + 1.41)) × ln((5.98 × 0.18) / (0.8 × 0.3 + 0.035)) 2. Z0 = 36.12 × ln(1.0764 / 0.275) 3. Z0 = 36.12 × 1.364 = 49.2 Ω

VerificationThe characteristic impedance is ~49.2 Ohms, perfect for standard 50Ω RF or single-ended logic routing.

Knowledge Base

Impedância típica de trilha PCB?

50Ω para single-ended. 75Ω para vídeo. 90Ω/100Ω diferencial para USB, HDMI, Ethernet.

Microstrip vs. stripline?

Microstrip: camada externa com um plano de referência. Stripline: interna entre dois planos.

Constante dielétrica do FR4?

~4,2–4,8 a 1 MHz. Em frequências mais altas (1–10 GHz): 3,8–4,2.

Preciso de simulador de campo?

Abaixo de 1 GHz: fórmulas analíticas são suficientes. Multi-gigabit: use simulador 2D.

Máscara de solda afeta impedância?

Sim, adiciona camada dielétrica que reduz ~2–3 ohms.

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