3D printed solder paste stencil, closeup. [Jan Mrázek]’s success with 3D printing a solder paste stencil is very interesting, though he makes it clear that it is only an evidence of concept. There are a lot of parts to this hack, so let’s step through them one at a time. To start with, it ends up that converting a PCB solder paste layer into a 3D model is a little bit of a difficulty. A tool [Jan] discovered online didn’t work out, so he relied on OpenSCAD and wrote a script( offered on GitHub )which takes 2 DXF files as input: one for the board outline, and one for the hole pattern. If you’re utilizing KiCad, he has a Python script( also on GitHub) which will export the essential data. The result is a 3D model that resembles a solder paste mask integrated with a raised border to match the board outline, so that the entire thing self-aligns by fitting on top of the PCB. A helpful function, for sure. [Jan] says the model envisioned here printed in less than 10 minutes. Workflow-wise, that certainly compares favorably to waiting for a stencil to show up in the mail. But how do the actual solder-pasting outcomes compare? 3D printed solder stencil on PCB, after using solder paste. [Jan] states that the printed stencil had a couple of flaws however it otherwise worked fine for 0.5 mm pitch ICs and 0402 resistors, and the truth that the 3D printed stencil self-registered onto the board was a welcome function. That being said, it took a great deal of work to get such results. [Jan]’s SLA printer is an Elegoo Mars, and he wasn’t able to have it create holes for 0.2 mm x 0.5 mm pads without very first customizing his printer for much better X/Y accuracy.
In the end, he admits that while a practical Do It Yourself solder stencil can be 3D printed in about 10 minutes, it’s not as though professionally-made stencils that give better outcomes are particularly pricey or tough to get. Still, it’s a neat trick that might be available in convenient. Likewise, a quick pointer that we stepped through how to make a part in OpenSCAD in the past, which ought to help folks new to OpenSCAD make sense of [Jan]’s script.