I’m trying to import a 6-layer PCB from Altium but I’m having trouble understanding the layer names. For instance, the imported layers column does not appear to include the bottom copper layer and there are no gnd power or signal layers in the KiCAD column even though they are in the PCB editor. If I select auto-match layers the matched layers column mostly shows Mechanical x to User.y. The bottom layer is not shown in the mated layers column but if I select import the bottom layer does import to the KiCAD bottom layer.
I created a PCB project that has a text string on each layer with the Altium layer name. Selecting auto-match and importing works much better than the layer match dialog would suggest. Top and bottom overlay, paste, courtyard solder and copper are correct and naming matches the Altium layers. The inner layers are mixed up with 3 inner planes mapped to User.Eco.1. This would seem simple to fix but I can’t make sense of the layer mapping dialog.
Instead of relying on auto-match, manually assign your internal layers to In1.Cu, In2.Cu, In3.Cu, etc.
For example:
Internal Plane 1 → In1.Cu
Internal Plane 2 → In2.Cu
Internal Plane 3 → In3.Cu
If you have power planes, map them to the correct inner copper layers.
If you wish to print the PCB, you may get some idea about the cost here: ALLPCB.com
I was seeing the same thing, in particular there was no Bottom Layer shown in the Imported Layers so I couldn’t match anything to B.Cu. I then decided to see what I would get if I just proceeded with the Auto-Match Layers and to my surprise my very complex 8 layer board was imported almost flawlessly. Some layers were swapped and the planes lost their pours, but footprints, pads, tracks, vias, teardrops, etc. were all imported.
I think this needs work because the B.Cu layer was listed as an unmatched layer, and there was no sign of Altium’s Bottom Layer so they couldn’t be matched manually, but they were matched somehow even if it wasn’t displayed.
That’s what I learned as well. I could manually recreate the missing information but I have several projects I would like to convert so I decided to dig into the KiCAD code to see if I could figure anything out. It’s a steep learning curve, a lot of work by some skilled developers has gone into this.
I wouldn’t be surprised if something has been inserted into the altium file to throw off parsing so I’ll add the Altium version, 25.3.3 build 18.
