Excellet video! Greta way of expalining and the reasoning for changes. I do would like to know if you have a link to the reflow oven. I have seen so many, but your explanation of how you worked out your design gives me confidence in the decision. :) Appreciated Peter AU
It's a controlleo3. whizoo.com. No affiliation, it's a little pricey for the kit and it takes some time to build, but I've been happy with mine. The cheaper "off-the-shelf" options are apparently terrible, but I haven't tried those.
Heat stake inserts are a lot more trouble than they're worth I just mold in a hex pocket and drop a standard nut in place and print over top you can print over regular nuts or lock nuts of various kinds and they cost next to nothing compared to the fancy heat stake inserts and they are a lot stronger.. You can also print clearance in so the nut will float a bit and allow for misalignment much more versatile than a heat stake insert. Interesting design.
I'm kind of afraid of inserting someone mid print, even though as long as it's below the current layer you should be in the clear. There are also out of plane inserts to contend with. I kind of agree though, heat press inserts are a PITA to get right. I need to play around with all the other options when I get some time.
While watching your video, I had an idea. To me this idea seems so obvious, that I'm almost certain that somebody else already thought of it and tried it, and there's some reason that it either doesn't work or isn't practical. Still, just in case, here it is: Would it be possible to make a modified toolhead for a 3D printer that could apply solder paste? So that it could be printed on to the pads directly without using a stencil. I can see one reason that this might not have been tried even if it were feasible, and that is that those people with the knowledge to actually make this are also people who make multiple copies of each PCB, so for them it would be impractical, but for a hobby-user who would often only make a single PCB, it might be a sensible solution, that they just don't have the knowledge or equipment to pull off.
I think i saw some Projects trying it (also with an Pick and place toolhead) but controlling the flow of the Paste to Dispense Just a small SMD Pad is hard
I've used something similar, a sort of CNC dispenser with a syringe for whatever viscous liquid you're using! We were doing adhesives, but I think they advertise it for solder paste as well. Converting a 3d printer would be an interesting project though, but it might be a little hard for some of the smaller components. I've also seen ink jet approaches companies are developing, which would be really cool.
Nice video, but you way overcomplicated the process. One generally only needs a flat surface, glass or plexiglass, then you put down your pcb and tape down similar thickness old pcbs around it to "lock" the board position, but it is still easily removed. Finally, you align a stencil over it and only tape one edge down to form a hinge. Lasts for thousands of boards. Your stencil is too thin. The stainless stencils from pcbway are completely flat on their own, so no need for vacuuming.
Eh, overcomplicating things is half the fun. I wasn't originally planning on adding the vacuum but thought it might come in handy. I've used the method you mention, I even mentioned it in the video, but it has some limitations. For small pads like on QFN footprints it can be a bit difficult to keep the stencil aligned. I've also got a bunch of flex PCBs to do, which are only 8 mils thick and hard to locate. I haven't tried them with the printer I made yet but I'm hoping it makes them much easier. As far as stencils the 4 mil isn't too far off. I think a 5 or 6 mil and pulling the size of the pads in might be better, I'll probably try that for the next one, but it is easy to get too much solder under the QFNs (particularly ones with thermal pads). Thicker stencils are actually easier for me to make. The brass I used came in roll form (which was squished in shipping) and that wasn't ideal, I'm looking for it in sheet form. As I say in the video, it isn't financially beneficial for me to make my own stencils, but I like doing it and it allows me to make changes in 10 minutes.
