Via capacitance is dependent on the via pad with respect to a reference plane opening, this can be thought of as a parallel plate in a sense. As far as the via impedance, I do not see how Polar is correct but maybe I'm just not familiar enough with their tool. A board house called me once claiming that the Saturn PCB Toolkit's numbers were closer than what they got from Polar in their actual measurements so they are pretty accurate. I use stated formulas given by the IPC or other industry standards is really all I can say. I do not know what Polar uses to calculate impedance's on any of their tools. Not sure where the rest of my reply went: I am sometimes asked why the Saturn PCB Toolkit has a different Z number here or there with respect to Polar and the answer is.I have no idea. Plane Opening Diam.=1,016mm Remaining parameters by default. Via Hole Diameter=0,254mm Internal Pad Diameter=0,255mm Ref. VP=0,2540mm (via pad diameter) AP=1,0160mm (anti-pad diameter) Er1=4,6000 (substrate dielectric) Zo:38.74 Ohm - Polar Application Note AP8178: Saturn PCB: At least similar results should be obtained, true? Why does it happen? SI9000e: When I compare the result with the same utility in the sarturn PCB software I get a very different value, to the same via characteristics. Hello! I tried a demo of the last version of POLAR SI9000e, it have a utility to estimate the impedance of a via (via pad/anti-pad coaxial calculation).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |