impedance of a rectangular piece of FR4, two layer copper

1. fr4 impedance per cm

Hello Friends,
I 'm trying to find the impedance of a rectangular 10*1 cm^2 of a pcb FR4
two layer copper 0.025mm per layer and h=1.55mm
I tried to measure but that was not satisfactory and i 'm trying to
compare measuring the impedance and then I will find the dielectric constant.

Thanks

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2. fr4 characteristic impedance

A slab of PCB material doesn't have a characteristic impedance - a trace etched on the PCB material has a characteristic impedance. The impedance of a trace on a PCB can be measured and is dependendent on the width of the trace, the thickness of the copper used on the trace, the frequency of the applied signal, the dielectric constant of the PCB material, and the distance from the trace to the nearest return copper structure (usually an underlying plane).

To measure the characteristic impedance of a trace on a PCB, you can use several different instruments - a time domain analyzer, a vector network analyzer, or a crude setup using a pulse generator and an oscilloscope. No matter what instrument setup you use, the technique is basically the same - you send a pulse down the trace, and look to see how it is changed by the trace.

There is an article that might be of help at: http://www.home.agilent.com/upload/c.../All/GTL91.pdf

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3. fr4 impedance

That 's Right , I was thinking in a trace etched on the PCB material, but i don`t know if there is a formula for the theoretic characteristic impedance like the
Microstrip Transmission Line Characteristic Impedance.

regards

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4. fr4 pcb impedance

There is a discussion of impedance calculations in the following paper:http://www.polarinstruments.com/supp...ts/IPC1999.pdf

There is a slide presentation that may be useful at:http://www.speedingedge.com/PDF-File...0Impedance.pdf

5. fr4 four layer trace impedance

Dear roderick81,