Hi All
I have managed to design a pcb through Kicad and export it as a STL file. I will using photoresist boards and be exposing the boards to UV light using a 3d resin printer.
My first attempt worked except the tracks were exposed to the UV light instead of everything else.
I think I need to invert the board for the UV exposure but cannot see a way of doing this in Kicad.
Can anyone please help?
KiCad is really focused on putting out accurate representations of the design, rather than processing them for a specific fabrication technique. Iām not aware of a way to intentionally invert a layer / output file.
From the description you gave, Iām guessing you are taking the .STL directly from KiCad and doing a single layer slice of it in the resin printerās slicer software? One silly / long way around this might be to export a dxf or svg of the copper layer annd edge cut layer into inkscape, invert the traces there, then import that into FreeCAD (or blender??) and extrude it slightly to have a 3D geometry for your slicer.
Someone who has done more home fabrication may have better suggestions for CAM software options here.
Yes I have been taking the STL file from KiCad and increasing the first layer exposure time.
I will look into doing it the way you said but yes it does seem a long winded way of doing it. Would be easier to print the PCB on Clear film and use as a mask.
I have been researching the mask layer and had mixed results. I can export just the mask layer and I get an exposure of the whole board with holes where pins are.
Should the mask layer not be the whole board with the tracks and pads omitted?
The purpose of the physical solder mask is to cover the traces but not the pads. The solder mask layer is inverted (by convention) so that the layer closely matches the copper of the pads (āholes where pins areā).
I did notice that the KiCad Plot system allows for Negative plotting on SVG outputs. That certainly removes the Inkscape step from my theoretical workflow. Iām not familiar with resin printers, but maybe someone else has a easy way to directly translate a SVG to a single layer exposure.
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Some Applicationās/Programās have an Invert (color) button.
Kicad does not. But, you can set Color-Themes.
The Color-theme panel has a full list of items to set colors for. Thus, you can set the Maskā¦etc
Video demoās simple Black/White themeās (I did not bother with Mask/etcā¦).
You would change the Theme before Printing/Plottingā¦
Further, you can create a Plugin to Toggle them (not shown).
Ok thank you. Will look into this further.
Thanks for the info.
I am struggling to see how setting colour themes has anything to do with the output of a STL file but obviously missing something.
I responded to Only inverting the Color (of PCB and items specific to the PCB).
STL has no Color. You can Color STL and export them with Colors in FreeCAD (and, probably other programs, too).
This looks promising.
Just trying to follow this example of opening an SVG file in FreeCad but not going as planned yet.
Opening a SVG file in FreeCad
I would recommend looking into FlatCAM.
Iām confused about what you wantā¦
Black & White STL ?
Black & White SVG ?
If STL, watch this Video below
If SVG, Kicad already āPlotsā SVG (and other formats using Plot, not Print). You can also save the FreeCAD file as SVG.
ADDED: I loaded the exported STL into ORCA (as if I wanted to 3D-Print it). Screeshot below shows the Front side with Track. The Pads are on the Bottom side (just as I wanted), not shown.
Thanks for the info.
The STL file generated from KICad exposes the tracks to UV light which means they will be etched instead of the rest of the board. If I was printing the file onto a clear sheet and using this as a mask it would be ok the way it is. But I am trying to eliminate the need for this and use the 3d printer to produce the mask.
So I need the STL file inverted so the tracks are not exposed to UV light.
I donāt want to use an SVG file but was suggested by @scone that this could an option to do this.
Ill take a look at the video.
With UVTools you can import Gerber files directly and save a file for your resin printer.