fr4 dielectric constant

hi all!

is fr4 a standard?

i mean if one material is said to be fr4, will other fr4 materials have the same characteristics?

also, will the dielectric constant change with the width of the fr4?

thanks much
vpm

The dielectric constant is only roughly specfied for standard FR4. You'll find tighter specifications with some manufacturer's FR4 qualities, so for applications, where er is an issue, you should specify a particular vendor and substrate quality - or choose a better specified RF substrate.

Hello vpmedina
I think that dielectric constant of a laminate is independent of its thickness. But about FR4, it's produced by various companies in the world. You can find them by googling web, then you can find dielectric constant of their laminates in the datasheets.
But as a rough approximation you can use εr=4.7.

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