Making PCBs with 3D printed stencil and UV paint

Details

I'd like to show how to prepare a PCB with 3D printed stencil and UV soldermask used as an etching mask. This process is pretty quick and doesn't require chemicals to develop the etching mask.

Pros:

no chemicals besides the soldermask, isopropyl alcohol and etchant are required
the stencil completely blocks UV, making it hard to overexpose the board; it also completly passes the UV in uncovered areas, making the exposure faster than with a plastic film
the stencil is reusable

Cons:

not suitable for fine-pitch components
requires adding "bridges" to the stencil to keep it from falling apart

I created a step-by-step guide in this video:

Files

pcb-auto-template.blend

Blender project with 3d-printable stencil generator (import DXF file and move to PCB collection)

blend - 872.58 kB - 07/22/2022 at 18:18

Download

Components

1 × UV-curable soldermask

1 × Rubber roller

1 × Copper laminate

1 × Isopropyl alcohol

1 × 3D printer with a heated bed

Build Instructions

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1

Prepare a 3D-printable file with PCB stencil

I'm using the following software: KiCad, Blender and Cura.

1. Open the PCB design in KiCad and plot a DXF file with a chosen copper layer.

2. Open the attached pcb_auto_template.blend file in Blender.

3. Make sure that DXF import add-on is installed in Blender (Edit - Preferences - Add-ons - find and check Import DXF)

4. Import the DXF files into Blender (File - Import - AutoCAD DXF)

5. Select and right click the imported drawing. Move it into PCB-Drawing-IMPORT-HERE Collection:

6. The stencil should be automatically generated thanks to the geometry nodes setup that was prepared in Blender template.

7. Stencil thickness and margin size can be adjusted if needed.

8. Now it may be necessary to put some "bridges" over the stencil, to keep it from falling apart. Some pieces were already included in the template file. They can be rotated, moved around and duplicated.

9. Now the entire stencil should be selected and exported as STL file (File - Export - STL option). Make sure to select "Selection only" option when exporting.
2
3D printing
Now the STL file should be sliced in favourite slicer (i used Cura) and 3D printed. The file can be mirrored before printing if necessary.

I'm using some expansion options to make the holes and clereances a bit larger:
- Horizontal Expansion -0.04mm
- Initial layer expansion -0.04mm
- Hole Horizontal Expansion 0.05mm
I also slowed the print down by around 50% (this needs to be experimented with).

After printing it may be required to do some minor post-processing, to further increase the clereances:
3

Preparing the PCB

I cut the PCB by scoring it multiple times with knife and breaking it. Eye and respiratory protection should be used. I'm using CEM-1 copper laminate, which has less fiberglass than FR-4 and is pretty easy to work with.

Now I clean the copper with abrasive material, and clean it further after that with some isopropyl alcohol.

The board prepared in such a way is ready for next steps.