PCB News - Analysis of wire impedance interference in PCB copy board design

At present, in the PCB manufacturing of printed circuit boards, the wires are mostly copper wires. The physical characteristics of copper metal itself determine that there must be a certain impedance in the process of conducting electricity. The inductance components in the wires will affect the transmission of voltage signals and resistance. The component will affect the transmission of the current signal, and the influence of the inductance in the high-frequency line is particularly prominent.

A certain piece of wire on the printed circuit board can be regarded as a very regular rectangular copper strip. Let’s take a piece of wire 10cm long, 1.5mm wide, and 50μm thick as an example. The impedance can be seen by calculation. .
The wire resistance can be calculated by the formula:
R=ρL/s (Ω)
where L is the length of the wire (meters), s is the cross-sectional area of the wire (square millimeters), and ρ is the resistivity ρ=0. 02. The resistance value of the wire is calculated to be about 0.026Ω.
When a piece of wire far away from other conductors is much longer than its width, the self-inductance of the wire is 0.8μH/m, then a 10cm-long wire has an inductance of 0.08μH. Then we can use the following formula to find the inductive reactance presented by the copy board wire:
XL=2πfL
where π is a constant, f is the frequency of the signal passing through the wire (Hz), and L is the self-inductance per unit length of the wire (H). In this way, we can calculate the inductance of the wire at low frequency and high frequency respectively:
When f=10KHz, XL=6.28*10*103*0. 08*10-6≈0. 005Ω;
When f=30MHz, XL=6.28*30*106*0.08*10-6≈16Ω
Through the above formula calculation, we can see that the wire resistance is greater than the wire inductance in low-frequency signal transmission, while the wire inductance is much greater than the wire resistance in high-frequency signals.

The above is the introduction of wire impedance interference analysis of PCB copy board design. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology