I an currently trying to reconstruct a PCB in Altium from the Gerber files. So far, I have been able to import the Gerbers in a PCB document.

The existing Gerbers have through-hole pads that have a special shape in the inner layers (in green here):

enter image description here

I am able to set the pad in full-stack mode, but I am not sure on how I can achieve the pad shape of the old design (unless maybe create a custom pcb component).

enter image description here

Is there an easy way to do this?

  • \$\begingroup\$ The pad in green is called a thermal. The generation of thermals is controlled in the rules for planes when laying out a PCB. \$\endgroup\$
    – qrk
    Commented Jan 3 at 19:47
  • \$\begingroup\$ This link will take you, even without a valid license, to an excellent (and official) Altium forum: forum.live.altium.com (where all you need to do is register for an account). \$\endgroup\$ Commented Jan 3 at 20:03

1 Answer 1


The green arcs are a thermal relief for a connection to a plane on that layer.

They are not part of the pad stack, or defined in the footprint. They are created automatically when a via or through-hole pad has to connect to a plane layer or copper pour.

  • \$\begingroup\$ That would mean that there are planes on the two inner layers, but they are not shown in any way on the Gerbers. Is this a common thing with older PCBs? (Nobody knows in which software this board was done) \$\endgroup\$
    – ESD
    Commented Jan 3 at 19:52
  • \$\begingroup\$ Or they are actually inverted layers (meaning the drawed shapes are removed from the copper) ? \$\endgroup\$
    – ESD
    Commented Jan 3 at 19:53
  • \$\begingroup\$ My understanding is that in altium at least, what distiguishes a "signal layer" with pours from a "plane" layer is that on a signal layer the shapes represent copper while on a "plane" layer the shapes represent the absense of copper. \$\endgroup\$ Commented Jan 3 at 19:57
  • \$\begingroup\$ Yes, on a power or ground plane layer anything you draw is "not copper" - a hole in hte copper plane. \$\endgroup\$ Commented Jan 3 at 20:32

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