Understanding Footprint Wizard outline margins Dx & Dy

Hi experts,
I request your help to understand the body parameters in the KiCad footprint wizard.

  1. Parameters: “Outline X margin” and Outline Y margin"
    Question: Outline margin from which point? Is it the distance from (first/last) pin to the edge of the component on each side in the X and Y directions respectively?

  2. Parameter: Silkscreen inside
    Question: What exactly is meant by “Silkscreen inside”?
    I assume “silkscreen” is probably just another terminology used by the App-designer (kindly confirm or explain) for component “Courtyard” but what difference would it make whether the silkscreen is “inside” or “not inside”?

Further, I have made the experience that selecting the “silkscreen inside” (boolean TRUE) shrinks the component outline in “Y” direction whereas the outline (length) in the “X” direction remains unchanged.
Up to now, I have tried this just with one footprint template (S-DIP) in the wizard though. Therefore, I can’t say right or wrong because I simply don’t understand the purpose and function of this parameter.

Thanks for your kind advice/help in advance.

Of course, if needed, I can send more details with screenshots etc.
I am using the Kicad version (5.1.8)-1 release built on 64-bit Windows 10 OS.

Thanks and best regards

Which one?
There are 13 different footprint wizards.

Usually “margin” is used for difference between a pad outline and the cutout i the solder mask or stencil.

A simple way to get an idea is to enter some “weird” values into the boxes, and then see what changes.

Hi paulvdh,
"Which one?
There are 13 different footprint wizards."

The one I tried is the S-DIP wizard template.

I am using this template to create a “Box_header_2x10_pin_Counter_Clockwise” footprint.

Meanwhile, I have included the newly created footprint in my pcbnew. The layout of pin-holes and dimensions etc. is perfect. The device outline is visible on the silkscreen. The only issue is that it is 0.8mm too long in the “X” direction and 2.0 mm too wide in the “Y” direction.

Maybe I’ll simply neglect the “silkscreen inside” parameter i.e. leaving it blank (boolean. FALSE) and experiment - as you suggested - with “Outline margin” only using the hit-and-trial method untill the footprint outline dimensions match with the dimensions given in the device datasheet.

Many thanks for your suggestion.
Best regards

I’d think you do realize that after the wizard has run, the footprint is loaded in the Footprint Editor :slight_smile:

Those margins are listed in the “Body” tab, so it looks like they handle the offsets you wanted to change.

Unfortunately this footprint wizard does not run on my Linux box at the moment. Very likely for a bug for which there is already a fix, but is held back because of issues with Python V2 and V3 scripting on different platforms on which KiCad runs.

Silkscreen and courtyard are two different things. And, silkscreen is an industry term and given the credentials in your profile I’m surprised you haven’t heard it before. Though it might be a translation/locality issue. I’ve also heard of the same layer being called the “legend”. I’m not sure what it is referred to in the German EE circles (me not being German and all that…). The courtyard is the perimeter that is enforced for tooling allowances during manufacture. You don’t want the PnP head knocking already placed components because there wasn’t enough space left between them in design. The courtyard is almost an imaginary line because it is never directly reflected on the physical PCB, but the silkscreen are the lines, logos, notes, and reference designators printed in ink on the surface of the PCB.

“I’d think you do realize that after the wizard has run, the footprint is loaded in the Footprint Editor :slight_smile:

Yes, I know that after completion, the wizard exports the footprint to the Footprint editor. And this is where I finally have changed the device outline by simply editing it using the editor (giving X and Y start and end coordinates). Thus it was done in just two minutes i.e. no-hit and trial approach.
And while at it I also drew the courtyard using the same method. So finally it is done.

The wizard may not be perfect in all senses but still, it is a great tool indeed.
My compliments to the designer or the designer team of this tool. It makes life so easy.

Yes, I do realize that Silkscreen and courtyard are two different things, and - as you explained - I understand the background behind the courtyard.
Only that, while working with Wizard a few hours ago, I started guessing and making assumptions because I could not and still cannot differentiate between “silkscreen inside” and some silkscreen that might not be inside.
Probably some documentation on this wizard might help. Perhaps it exists already somewhere but I don’t know where.
Anyway, as mentioned above I find the Wizard a great tool and admire the work done by the Kicad team.

Thanks to both of you for your comments and help.
Best regards

NOTE: The below only relates the the S-DIP wizard, I haven’t checked the other wizards to even see if the same fields for the body tab exist. I would expect different wizards to have different fields.

On my system I get an immediate update in the footprint wizard previewer so I can see what the “silkscreen inside” boolean does for DIP packages. With it TRUE the silkscreen is drawn between the two rows of pins. This does a few things:

  • The silkscreen outline more closely approximates the body of a DIP IC package.
  • More of the silkscreen is covered (hidden) when a bare IC is loaded into the board.
  • There is less space left in the silkscreen for text under the component.

With it FALSE the silkscreen is drawn outside the two rows of pins. This does a few things:

  • The silkscreen outline more closely approximates the body of a DIP Socket package.
  • More of the silkscreen is still visible when a bare IC is loaded into the board (perhaps prompting an inspector that someone forgot or decided not to use a socket).
  • There is more space left in the silkscreen for text under the component. (Notes to the assembler that aren’t needed on a completed board.)

Looking at the x and y margin specification, that seems to be relative to the edge of the pads and is probably important to help keep silkscreen off of exposed copper. Though, you can force the silkscreen lines over the exposed copper of the pads by using negative values here.

1 Like

Thanks a lot for this investigation. I’ll check it out.
Wish you all a merry X-mas and a happy transition into (hopefully) soon a Corona-free new year 2021.
Best regards

1 Like

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.