Milling PCB's

v2

You will be milling the copper away. Soldering is done on the copper side. The components go on the other side, so in the PCB software, make the traces on the bottom layer! (This layer will still be mirrored horizontally later).

Make circuit and PCB layout in Kicad.

• Set a margin of 0.5mm
• Use 1mm wide traces
• Try to enlarge the pads as much as possible while respecting the margin. You can speed up the process for similar components by changing 1 pad, then choose Copy pad properties to default from the context menu. Then set the selection filter (right bottom window) to only pads. Box select to select all wanted pads choose Paste default pad properties to selected.
• Don't draw GND tracks, as you'll use a ground plane (copper pour) with the option 'fill zone'. This prevents unnecessary overlapping track geometry in Freecad & Rhino.

Save the Kicad project.

• Open Freecad
• Select the KicadStepUp workbench.
  • If this workbench isn't there. Install it:
    • automatically: Freecad > Tools > Addon manager. Search for “KicadStepUp” and click install
    • Manually: copy the kicadStepUpMod folder from Github to the computer: ~/Library/Application Support/FreeCAD/Mod/kicadStepUpMod

• Click the Load Board icon and select the Kicad pcb file (.kicad_pcb extension)
  • Click OK on a few popups
  • The PCB without the pads and traces appears
• Click the Add tracks icon and select the same Kicad pcb file (.kicad_pcb extension)
  • The pads and traces appear
• In the model panel, select the top object and export: file > export. Select STEP.
• 

Open Fusion 360

Organize the files

• Upload the STEP file
• The file comes in the following components:
  • PCB (the PCB board itself)
  • PCB Sketch
  • top pads
  • bottom pads
  • top tracks
  • bottom tracks

* Delete the PCB sketch and the top pads components

Align the pads with the tracks on the Z-axis:

• Select the bottom pads components and press M.
• Move the pads up 0.01mm. Now they are exactly the same height as the traces. (Check in side view)

Extrude the pads. The pads are positioned just below the PCB. Extrude them into the PCB:

• Only show the pad component
• Press E to extrude. (You might be asked to capture the location of the object, click Capture).
• Drag a selection rectangle over all the pads.
• You can now show the PCB component to make sure you're extruding into it.
• Set distance to 0.02mm upwards and operation to New body

Info: We're not joining because due to the many faces overlapping each other this often doesn't work.

Extrude the tracks

• Only show the tracks component
• Press E to extrude.
• Drag a selection rectangle over all the tracks.
• Set distance to 0.02mm upwards and operation to New body

Extrude the zones (if you have any)

• Only show the zones component
• Press E to extrude.
• Drag a selection rectangle over the zones.
• Set distance to 0.02mm upwards and operation to New body

Go to Manufacture mode

• Create a setup and select all objects (PCB, tracks, Pads and zones) as the model.
• Add a drilling operation
  • Select the hole face of the hole through the copper. If that doesn't work, try on the holes of the PCB object.
  • Check select same diameter.
  • Set the bottom height to bottom height: lowest of model -0.1mm
• Add a 3D contour operation and set the bottom height to top height -0.1mm.

Todo:

• I don't like the areas of the holes to be milled already. How can this be avoided?
• Organize the PCB drills for differently sized holes.

Export to SVG

• Go to the PCB editor, Fabrication outputs > Gerbers
• Set 'Plot format' to Gerber.
• Set the output folder location
• Only enable the B.Cu (back) layer and the Edge.Cuts layer
• General options
  • Enable: Check zone fills before plotting
  • Enable: Use drill/place file origin
• Gerber options:
  • Enable: use extended X2 format
  • Enable: Include netlist attributes
• Plot and generate the drill files (default settings)

Add the drill data to the svg files

• Go to https://tracespace.io
• Drag all the Gerber files onto the website and download the generated SVG file. (This is a good way to include the holes into the SVG file)
  • This generates 5 SVG files:
    1. bottom
    2. top
    3. back copper
    4. edge cuts
    5. holes

Combine the SVG data to a workable file

• Open the back-copper file in Inkscape

• edit > select all

Get rid of clones

• edit > clone > unlink clones recursively. The clone objects have now been changed to circle and rectangle objects

Change objects to paths

• path > objects to path

Stroke to path

• path > stroke to path

ungroup x times (until there are no folders anymore)

• path > union

Now there is only a single path - file > save as. (this is the prepared SVG file)

- open the Drill SVG file in inkscape - Align it by hand – an automatic way would be much nicer. This is doable for now.

- select the folder containing all the circles – * path > objects to path – combine – select the folder, and ungroup. Now there are only 2 paths – select the 2 paths – * path > difference

Option 1: create circuit in Kicad, export Gerber files and import in Fusion 360 for milling

Option 2: create circuit in Fusion 360: - In Fusion 360: File > new electronics design

—

BAD: the circles are made up from several arcs. This way Fusion can't select it for drilling.

• In Inkscape, I draw a circle (object), I import it in Fusion, then it's good.
• This is the case somewhere in the steps to prep the SVG file in Inkscape.
• Can I prep the inkscape file without losing the clean circles? Or can I simplify a collection of arcs to become a circle again?

• open 'bottom.svg' in inkscape
• There are 3 layers: Clone-masked, clone and rectangle.
• for now, delete the 1st (clone masked) and 3rd layer (rectangle)
• right-click on the FOLDER icon, then edit > clone > release clone. Then the unselectable

—

Vaguely related

- Export a kicad PCB to fusion to create a cover