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Cross section tool and impedance calculations

TH Designs

I ran into something the other day and have been working with tech support on, but thought I might get some answers here.

Four layer board, two inner layers set to planes (and shield) FR4 material.

In the Setup - cross section tool, when I try to calculate the trace width based on a given impedance and stack up, the impedance is always 60 ohms. For example, I open the cross section tool and select Show Single Impedance.  The default impedance shows as 60 ohms. If I try to change it to 50 ohms by manually editing the cell, it resets to 60 as soon as I click out of the cell.

If I try to change it by using the drop down boxes at the bottom of the window; Layer Type - Conductor; Material 1oz cu; Field set to - Impedance; Value Set to - 50; then select "Update Fields", nothing happens.

We tried multiple things yesterday. I even sent the board file to tech support and it works just fine for them (figures.....)

I tried it on a different computer at my home office and the impedance is displayed in exponential format, not in ohms.

A couple of screen shots:

Parents
  • oldmouldy
    This calculator depends upon the SI tools. Any chance that you installed "only" the licensed products? (Maybe from a control file during product installation) The "defaults" come from Analyze>Preferences, you should be able to view them from the menu. BUT I am pretty confident that the calculator behind this is some "SI magic", possibly Java from the SI install, it might be possible that a restricted install does not include this, likely an oversight on the part of the installer. See what you have in <Install_dir>\share\pcb\signal - I have over 200 items in there, cds_interconnect.iml is of interest here, it is the interconnect models and <install_dir>\share\pcb\etc\context, there are some tlcalculators files, it's possible they do the actual calculations for the cross-section. I would have thought that you would have got "at least" some "missing files" messages in the Command Window for any missing "stuff" though.
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  • oldmouldy
    This calculator depends upon the SI tools. Any chance that you installed "only" the licensed products? (Maybe from a control file during product installation) The "defaults" come from Analyze>Preferences, you should be able to view them from the menu. BUT I am pretty confident that the calculator behind this is some "SI magic", possibly Java from the SI install, it might be possible that a restricted install does not include this, likely an oversight on the part of the installer. See what you have in <Install_dir>\share\pcb\signal - I have over 200 items in there, cds_interconnect.iml is of interest here, it is the interconnect models and <install_dir>\share\pcb\etc\context, there are some tlcalculators files, it's possible they do the actual calculations for the cross-section. I would have thought that you would have got "at least" some "missing files" messages in the Command Window for any missing "stuff" though.
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