[giantg2]

This looks great! I've ordered stencils and do 3D printing... kicking myself for not thinking of it.

On the other hand, it gave me a great idea. What if you could 3D print the solder paste right onto the PCB using a tool that swaps out the hot end?

[smcameron]

At my local hackerspace, people sometimes laser cut solder stencils out of transparencies -- the plastic sheets you use with overhead projecters. The trick is to put a piece of paper under the transparency when laser cutting, otherwise they tend to melt too much and deform, but somehow the piece of paper prevents this, maybe the laser needs something non-transparent to interact with to get the heat in quickly and move on quickly. Anyway they worked pretty well, but obviously not as durable as steel, so after some number of uses they start to wear out. (Can't remember how many really, but probably something like 20? more than just 3 or 4 I think. Probably also depends on the density of holes, a big swiss cheesed area will fail sooner.) If the circuit's not too big you can cut several stencils out of one transparency all in one go.

[themmes]

The opulo.io LumenPnP project does that, he has added a syringe to deposit solderpaste to his pick ‘n place machine.

[rajnathani]

For very thin stencils, I doubt plastic 3D printing or even laser-cutting plastic works, as such thin plastics would deform rather than remain flat-ish rigid like steel stencils.

Also for 3D printing solder paste, this technique is called solder jet printing. But it isn’t very popular in the industry (despite being less wasteful) due to it being slower than stencil solder printing.

[jazzyjackson]

There’s a minimum feature size of course but for the larger end of surface mount I’ve had good luck with a cheap craft cutter (silhouette cameo etc) cutting a stencil via vinyl sticker, one time use but for the prototyping stage nice and quick.

Laser etching plasticized Mylar (anti-static plastic bags electronics get shipped in) worked well too; because there’s a metal grid embedded in the plastic so you vaporize plastic but small features hold together.

[amelius]

I also wonder how well it works.

When I manually try to squeeze solder paste from a syringe it often doesn't stick on the board (unless I preheat it but that is more cumbersome if there are components on the flip side of the board).

[hjadal]

They didnt swap the tool, but Project Binky kinda did that: https://youtu.be/FzrZoVKT8gM