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.
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).
Cheap 3d printers are not terribly accurate, and the hot filament moves a bit (e.g. elephant foot). This method might not work well if your board is large or has very small components.
Also, even after ironing the surface will not be fully flat and some paste can end up in the space between the lines and go wasted.
A cheap low-power laser cutter is about the same price as a very cheap printer, which may be a better option if you can dial in the accuracy needed.
For those of us without the cash/apartment space for a PNP, has anyone experimented with a stencil system for populating passives? Is that even a thing?
My PCB project's population time is currently 11 hours the last time I did it, from blank to tested, for one unit. The largest amount of time spent is on the resistors and capacitors - over 200 of them.
In general, most single-sided PCB work with 0.5mm pitch components can be done by hand with a metal stencil + dry-wall trowel edge, SAC305 Type T4 or T5 paste, hot-air rework hand tool, and or a toaster oven re-flow kit (will often smoke flux due to bad temperature profiles.)
Getting a PCB mostly factory assembled for you is likely the better choice if you live in a building, as dropping hundreds of 100nF MLCC on a project can be brutal.
I guess the answer is yes one can do prototypes by hand if you take design considerations for pad access (sloppy mechanical tolerance for pencil/air rework), but probably one should be spending their time on design for lab EMC/EMI. =3
Robert Feranec does quite a few EE interviews, factory tours, and is generally accurate 97% of the time.
Could also keep your design tolerances less tight (QFN>BGA), and use a cheaper PCB fab house.
In general, for small discreet components they should be able to partially pre-fill the PCB for under $23/pc. The expensive/sensitive stuff you manually add later.
Air-tweezers and a magnifier also do work, but you will get a sore back pretty quickly.
There were a few manual-first exceptions I saw with fussy RF component selection (better s parameters if mounted upside-down), instrumentation grade high-precision components, pricey chips, and avoiding BGA x-ray pad inspection.
Setting up a small home PnP takes time, practice, and space. Not necessary if you just dropped on 5 chips using generic stencils, and re-flow. =3
I am aware, yes. After the paste deposition via stencil, doing passives manually takes hours. I'm asking if anyone's done anything interesting with stencils for placing those.
Good stencils are like $10 if you order them with the PCB, so I honestly don't get the appeal this time. Unless it is aimed at people who make their own PCBs (?)
Yes, that's the usual approach. Mylar sheets for short runs, stainless steel sheets for production.
3D printing in PLA probably won't have enough dimensional accuracy for fine pitch boards or boards of any size. The demo shown is a very small coarse pitch board.
The thickness of the stencil matters, because that determines how much solder paste you are laying down. This approach is going to produce thick stencils.
There are CNC machines for laying down solder paste. Here's one.[1] It does a few more jobs, too. The various CNC desktop board-making machines are still too expensive for most hobbyists, though.
You could solve the inaccuracy by just using a resin printer, that should have enough accuracy (maybe with some fiddling with the settings/trying out resins, light can bleed to the sides of the tiny holes needed). Although I have never done a stencil that was very fine but did fine silicone moulds with them.
Always vent to outside through an activated charcoal mesh bucket. These just lower the smell, and do almost nothing to protect against nasty melted plastics or solvents. =3
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?
The opulo.io LumenPnP project does that, he has added a syringe to deposit solderpaste to his pick ‘n place machine.
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.
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).
Cheap 3d printers are not terribly accurate, and the hot filament moves a bit (e.g. elephant foot). This method might not work well if your board is large or has very small components.
Also, even after ironing the surface will not be fully flat and some paste can end up in the space between the lines and go wasted.
A cheap low-power laser cutter is about the same price as a very cheap printer, which may be a better option if you can dial in the accuracy needed.
For those of us without the cash/apartment space for a PNP, has anyone experimented with a stencil system for populating passives? Is that even a thing?
My PCB project's population time is currently 11 hours the last time I did it, from blank to tested, for one unit. The largest amount of time spent is on the resistors and capacitors - over 200 of them.
In general, most single-sided PCB work with 0.5mm pitch components can be done by hand with a metal stencil + dry-wall trowel edge, SAC305 Type T4 or T5 paste, hot-air rework hand tool, and or a toaster oven re-flow kit (will often smoke flux due to bad temperature profiles.)
Getting a PCB mostly factory assembled for you is likely the better choice if you live in a building, as dropping hundreds of 100nF MLCC on a project can be brutal.
I guess the answer is yes one can do prototypes by hand if you take design considerations for pad access (sloppy mechanical tolerance for pencil/air rework), but probably one should be spending their time on design for lab EMC/EMI. =3
Robert Feranec does quite a few EE interviews, factory tours, and is generally accurate 97% of the time.
https://www.youtube.com/@RobertFeranec/videos
I know all of this; assembly of a $400 board usually has a MOQ of 5 off the top of my head, which for a board that is a prototype isn't feasible.
I know about how to do reflow. I'm asking about the population step after paste deposition.
Could also keep your design tolerances less tight (QFN>BGA), and use a cheaper PCB fab house.
In general, for small discreet components they should be able to partially pre-fill the PCB for under $23/pc. The expensive/sensitive stuff you manually add later.
Air-tweezers and a magnifier also do work, but you will get a sore back pretty quickly.
There were a few manual-first exceptions I saw with fussy RF component selection (better s parameters if mounted upside-down), instrumentation grade high-precision components, pricey chips, and avoiding BGA x-ray pad inspection.
Setting up a small home PnP takes time, practice, and space. Not necessary if you just dropped on 5 chips using generic stencils, and re-flow. =3
What? These stencils are just for solder paste placement, you still need to actually place your components some other way before reflowing.
I am aware, yes. After the paste deposition via stencil, doing passives manually takes hours. I'm asking if anyone's done anything interesting with stencils for placing those.
Good stencils are like $10 if you order them with the PCB, so I honestly don't get the appeal this time. Unless it is aimed at people who make their own PCBs (?)
I mean, why not laser cut a mylar sheet? That's an existing method and works well for 0603 footprints and similar, and is also quicker.
Yes, that's the usual approach. Mylar sheets for short runs, stainless steel sheets for production. 3D printing in PLA probably won't have enough dimensional accuracy for fine pitch boards or boards of any size. The demo shown is a very small coarse pitch board.
The thickness of the stencil matters, because that determines how much solder paste you are laying down. This approach is going to produce thick stencils.
There are CNC machines for laying down solder paste. Here's one.[1] It does a few more jobs, too. The various CNC desktop board-making machines are still too expensive for most hobbyists, though.
[1] https://www.voltera.io/products/v-one
You could solve the inaccuracy by just using a resin printer, that should have enough accuracy (maybe with some fiddling with the settings/trying out resins, light can bleed to the sides of the tiny holes needed). Although I have never done a stencil that was very fine but did fine silicone moulds with them.
There are quite a few people who own a 3D printer but not a laser cutter. And not everyone can or wants to use an external service.
stench ill
Sounds like you need a fume extractor!
Always vent to outside through an activated charcoal mesh bucket. These just lower the smell, and do almost nothing to protect against nasty melted plastics or solvents. =3