why should we use FR4 epoxy substrate

why should we use FR4 epoxy substrate

Hi

Well one reason is that it is more available and MUCH cheaper than any other PCB material.

Regards

It is just cheapest that's why. If you try to find Rogers RT Duroid, it will be very expensive and is available mostly on orders only.

Hi,
Not only the question of price is relevant, than it does exist some other (and more cheap! , PCB basis material too!
FR4 has good parameters for most applications, mechanial, electrical & climatic stabilties end even economical aspects too...
Greetings!
K.

karesz said:

Hi,
Not only the question of price is relevant, than it does exist some other (and more cheap! , PCB basis material too!
FR4 has good parameters for most applications, mechanial, electrical & climatic stabilties end even economical aspects too...
Greetings!
K.

Click to expand...

what is the frequency range that this substrate support???

buzzi said:

what is the frequency range that this substrate support???

Click to expand...

There is no clearly defined frequency range.

FR4 has much more dielectric loss than "good" microwave substrates. If loss does not matter, you can use it at high frequencies. But if you need low loss for microstrip filters, then FR4 is a bad choice.

The permittivity of FR4 is not well defined, it will be somewhere between 4.2 and 4.9. If you need smaller tolerances, use a microwave substrate (Rogers, Taconic etc.)

FR4 can support 2-4GHz max, if you don't care about loss etc.

FR4 pcb cannaot handle high powers at microwave frequencies .

There are FR1...N ? Do you know where to buy ?

Rogers Material

this link provides logical answers to buzzi perhaps.

FR4 is cheap and good enough for general-purpose applications.

FR4 means - Fire Retardant UV-94 meaning Flame dies off in less than 10 seconds and Glow less than 30 seconds and there MUST BE NO falling burnt ash.

Supported frequency up to 4GHz to ensure dielectric constant stays between 4.2 to 4.9, usually 4.7 are commonly available in the market.
If you operate it above 4 or 5GHz, dielectric constant will be greater causing tangent loss, and this explains why to use Roger boards at higher frequency.

buzzi said:

why should we use FR4 epoxy substrate

Click to expand...

FR-4 is mostly used to keep the price down where loss is unimportant. Making RF on FR-4 can be done, but it is easier and more stable to make it on ie. a Rogers substrate which is ceramic and not an epoxy treated glass fiber substrate as FR-4 is. Rogers is more expensive but it varies very little from your design and therefore making it more stable than the FR-4. This is very important when the frequency is increase to some GHz, because the ceramic surface is more plane and not so bendable as FR-4.

---------- Post added at 06:38 ---------- Previous post was at 06:25 ----------

Also FR-4 does not matter on digital signals. Mostly it's a problem on RF signals because of the frequency change due to the nonlinear surface of FR-4. So usually FR-4 are used because its cheap for signals that does not make any or little difference anyway, meaning less expensive product for the costumer.