Dielectric materials in PCB

Hi,

In this page you have a table of comparisons between different dielectrics.


Regards

Thanks, I notice that lower the dielectric constant, Dk, higher the CTE-Z.

CTE-Z is coefficient of thermal expansion, right ? what does it means if CTE-Z is high, more expansion or less expansion in z-direction ?

Also I am looking for which material is FR4, what is the name, ID or part number of FR4 dielectric ?

I also don't find cost comparisons between the followings.

Rogers Corporation (Rogers_4350)
Panasonic (MEGTRON 6)
Isola Group (Standard FR4_LP)

Hi,

joniengr said:

Thanks, I notice that lower the dielectric constant, Dk, higher the CTE-Z.

CTE-Z is coefficient of thermal expansion, right ? what does it means if CTE-Z is high, more expansion or less expansion in z-direction ?

Click to expand...

the CTE is the Coefficient Thermal Expansion, when your PCB heats ups it changes a little its dimmensions. If your CTE-z is high, the PCB experiments more expansion in the z-axis. The parameter has the units ppm/ºC.

joniengr said:

Also I am looking for which material is FR4, what is the name, ID or part number of FR4 dielectric ?

Click to expand...

For FR4 you can find plenty of manufacturers, you can google them.

joniengr said:

I also don't find cost comparisons between the followings.

Rogers Corporation (Rogers_4350)
Panasonic (MEGTRON 6)
Isola Group (Standard FR4_LP

Click to expand...

If you don't find prices maybe you have to ask manufacturer for a quotation.

Regards

Thanks for reply.
High CTE-Z means more expansion in z-direction due to heat. Then I guess the lower dielectric constant materials are not good to use in heat environment in PCBs.

joniengr said:

Thanks for reply.
High CTE-Z means more expansion in z-direction due to heat. Then I guess the lower dielectric constant materials are not good to use in heat environment in PCBs.

Click to expand...

I don't know how CTE-z is related with dielectric constant, but if you have a heat environment you have to get a good Thermal coefficient of the dielectric constant (Dk) and a good thermal conductivity.

Oh, I get it now. The CTE-Z is Not linearly related to dielectric constant (Dk). But lower CTE-Z material will expand less in thermal/heat environment, right ? So, we should chose a dielectric material with lower CTE-Z in PCB stackup if running in heat environment.

joniengr said:

Oh, I get it now. The CTE-Z is Not linearly related to dielectric constant (Dk). But lower CTE-Z material will expand less in thermal/heat environment, right ? So, we should chose a dielectric material with lower CTE-Z in PCB stackup if running in heat environment.

Click to expand...

That is correct. Now you have to choice a good one.

There are numerous variations of FR4, the term is a generic reference to Flame Retardant, 4 refers to woven glass reinforced . Look at ISOLA as well as manufacturers already mentioned. There are different glass weaves such as :

For any design you are best talking to at least 2 PCB manufacturers, give them any specific requirements such as impedances required, layer count, copper weights etc. and they will provide builds based on readily available laminates that will fulfill your requirements... Fancy laminates usually incur increased production costs, so only use what is needed for the design.