I generated gerber files to the pcb manufacturer, but I noticed that the top pad master (.GPT) was not generated, the top solder mask (.gts) was.

  • The pcb manufacturer did not complain, but I'm wondering, what can happen if top pad master (.GPT) was not generated ?
  • Why it did not appear as option to be choosen in altium when I generate the gerber files ?

With my best regards

  • 1
    \$\begingroup\$ What should a top pad master gerber file be used for? Neaver heard of such a file during more than 3 decades of practice in design and manufacture of PCBs. \$\endgroup\$
    – Uwe
    Commented Feb 18, 2019 at 19:12
  • 1
    \$\begingroup\$ @Uwe - you may need more than 40 years practice to recall pad masters, mylar sheets and Bishop Graphic pad patterns. \$\endgroup\$ Commented Feb 18, 2019 at 20:46

2 Answers 2


In ancient times when PC boards were layed out using sticky tape and Bishop Graphics pad patterns on mylar film, you would make a pad master showing all pads, and that mylar would apply to both sides of the board. The single pad master ensured that the pads on both sides of the board would line up. You would make separate mylars for top and bottom side copper tracks (but no pads).

Later, red and blue tape for tracks were used, with black pads - then a single mylar sheet could be used for both sides of the board - the separate pad master was no longer required. Photographic tricks were used to produce the top and bottom artwork, so the red tracks would only show on one layer, and the blue tracks on the other. The black pads would show on both layers.

Now, with surface mount parts on both sides, and multi-layer boards, a pad master would be useless, as you need different pad patterns for each layer.


Normally when you generate Geber files with altium you have :

  • .GTL : Top copper
  • .GTO : Top overlay (silks)
  • .GTP : Top paste (for stencil)
  • .GTS : Top soldermask

And Other layers, drill file and at least 1 mechanical layer for cutout.

If you plan to solder components your self (with soldering iron) you don't need you don't need stencil.

If you use reflow it's easier to use stencil for applying solder paste.

Best regards


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