What is the frequency range using FR4 LAMINATE in circuits?

[elf61]

hi frends
What is the frequency range of using FR4 LAMINATE in circuits?

 

[metu]

FR4 Laminate [hlp]

as far as I know it can be used up to 10GHz but we use other substrates at such high frequencies

 

[House_Cat]

Re: FR4 Laminate [hlp]

The usable frequency for FR4 depends on what kind of circuit you have, and what FR4 you are using. FR4 is not just one material with one set of characteristics - the FR4 rating only specifies what the flamability of the material is. Circuitwise, you can design compensation for some losses that extend the usable frequency/edge rate of any of the many types of FR4.

In a digital circuit, the clock frequency or data rate is less important than the edge rate of the signal. The faster the edge, the more signal loss and distortion there will be. Pre-emphasis and low level triggering can allow higher data rates and edge rates than would normally be expected. Circuits and backplanes with data rates of 10gbs have been designed and successfully built.

In an RF circuit, the usable range of FR4 depends on how much signal loss you can tolerate. FR4 dielectric constant varies with frequency, and the loss increases with frequency. Careful choice of FR4, trace width, trace finish, elimination of stubs, and avoiding vias are some ways of extending the useful frequency. I've successfully designed circuits on FR4 up to 9gHz myself.

There's an article about a 3.8gHz FR4 design at: **broken link removed**

Here's another article about loss considerations: **broken link removed**

The bottom line is that FR4 can be used for just about any circuit depending on how much loss you can tolerate, and what compensation you can build into the circuit. The best way to tell if your design will work is to model it using a good 3D modeling program. FR4 comes in wide variety of resins, glasses, and resin-to-glass ratios. You can choose the dielectric constant from a range of about 3.5-4.7. Likewise, a wide range of dissapation factors are available depending on the makeup of the FR4.

 

[FANT]

Re: FR4 Laminate [hlp]

We use FR4 up to 2 GHz for professional systems and up to 3,5 GHz for commercial users.
For frequencies above 2 GHz the Er and the tangent loss is very variable from batch to batch and requires a lot of tuning time.

Mandi