Over on his YouTube channel the vivacious [Stephen Hawes] tells us that we never need to buy solder stencils again!
A big claim! And he is quick to admit that his printed solder paste isn’t presently quite as precise as solder stencils, but he is reporting good success with his technique so far.
[Stephen] found that he could print PCBs with his fiber laser, populate his boards with his LumenPnP, and reflow with his oven, but… what about paste? [Stephen] tried making stencils, and in his words: “it sucked!” So he asked himself: what if he didn’t need a stencil? He built a Gerber processing, G-code generating, machine-vision implemented… website. The LumenPnP Pasting Utility: https://paste.opulo.io/
The WebAssembly running in the Chrome tab itself connects to the LumenPnP and performs the entire pasting job automatically, with machine-vision fiducial calibration. Automatic alignment with fiducials was critical to the project’s feasibility, and he achieved it using machine-vision from the OpenCV library.
In the video heshows us how to jog the camera to the home fiducial, load the Gerber files, and initialize the job. He’s implemented camera jogging by clicking on the image from the camera to indicate the desired target location, which looks like a very handy feature to have!
Some initial setup just needs to be done once at the beginning to setup your board, additional board prints can then self-calibrate from the fiducials. The Z-index for the dispenser needs to be calibrated, and other job settings include nozzle offset calibration, dispense degrees, retraction degrees, and dwell milliseconds.
If you’re interested in other options for solder stencils be sure to read Solder Stencil Done Three Ways.
Great work….although.
I have a paste dispenser on my Manncorp 384v2…the Martin dispenser. Apparently, it was a $15k option when the machine was new. It seems to work well but it is very slow.
Depending on the solder amount and whatnot…it can add a lot of time.
Where I see this being more useful is for adding glue when needed to the bottom side parts.
I recently bought one of these (https://www.tindie.com/products/danm/edispenser-for-solder-paste-adhesives-and-more/) off of Tinder for just such a function – though I didn’t have a machine to put it on. I’m half tempted to put together a cartesian platform and see if I can make it work. The Vision components are handled by the computer its hooked up to.
As an aside, I have suspected that Stephen and the rest of the crew at Opulo have been working on a web-based PnP software tool to reduce reliance on OpenPnP. This all but confirms that as it implements a substantial set of the necessary pieces to get moving on such a thing.
Solder paste dispensers are not what people usually look to get from Tinder, have they branched out?
Why not using physical blocker to be sure that the pcb is always in the same position?
PCB edges/holes are not always routed perfectly, hence why you need fiducial markers to get the last bit of alignment.
“PCB edges/holes are not always routed perfectly”
They are if the board is milled successfully! I mean, vias and through-hole pads need more accurate placement than solder paste, so you could certainly add holes to mechanically align the board in the same step.
But perhaps this guy is making SMT-only boards, and cutting them out by hand or something. Or maybe he wanted to do an MV project for its own sake.
I was under the impression that board routing was done at different phase of the processes as drilling. Looking at PCBWay’s capabilities specs, the tolerance on routed board edges is 0.2mm which is more than the .15mm minimum annular ring spec for vias.
Additionally, if you’re doing the whole paste deposition thing instead of a solder stencil, you’re probably doing some quick turn prototype level of volume where building a design specific jig wouldn’t make a lot of sense.