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mulfycrowh , 06-25-2023, 08:43 AM

Hi everyone,

I have a quite big difference for the impedance calculation between Altium and Saturn PCB.
Here attached the screenshots.
It is about "Signal2".

Any idea maybe?

Thanks a lot!

qdrives , 06-25-2023, 02:15 PM

One thing that has an influence is that H2 in PCB toolkit is from the top of the copper to the reference plane.
However, some of the resin needs to flow between the tracks and hence, the distance between the two copper layers is less then the unpressed prepreg layers.
If I fill that into PCB toolkit is drops to ~97E.

mulfycrowh , 06-25-2023, 02:29 PM

Usually there is no difference between both software.
I have checked and rechecked and I don't see potential errors, something I could have wrongly entered.
I also tried with one material instead having 2 sheets of material, same result...

qdrives , 06-26-2023, 01:35 PM

Megtron 6 is not from Isola so you cannot use their stack-up tool.


Putting the values in Sierra circuits: Result = 90E differential. Similar to Altium.
​


Using TerraGreen from Isola (DK ~3.2) with comparable thicknesses gets 104E.




DigiKey (https://www.digikey.nl/en/resources/...race-impedance) ~90E
EEweb (https://www.eeweb.com/tools/edge-cou...ine-impedance/) ~118E

mulfycrowh , 06-27-2023, 01:15 AM

@qdrivesThank you so much. I'll take a look at it.