IMHO, the hardest part of doing SMT/SMD soldering at home is to get the solder into all the right places. I’ve never quite gotten the hang of stencils, and while I don’t mind depositing solder manually, it’s always a smeary mess, and I haven’t found any tools that can make it better. (Not sure about digital glue dispensers, since they seem to be fairly expensive.)
Anyways, my idea is this: Use a super-fine syringe to to deposit flux instead of solder paste. Flux tends to be sticky, but can be bought in any viscosity you like, from water-like to paste. I’m thinking that something that flows relatively easily should be much easier to deposit with a syringe, and in far smaller droplets than solder paste. (because I can use finer needle) Also, it should be possible to “paint” a surface with the liquid I think. Maybe something like a super-tiny brush could also work.
Assuming step #1 above works well, step #2 would be to take some finely ground solder power and sprinkle it over the board. The power should stick where the flux is, but not so much to the dry parts, so turn the board over to get rid of the extra powder, then place components and bake…
I haven’t found solder powder for sale, so I I would probably have to grind some up if I want to test this. Not sure what to use since I don’t want to sacrifice the mortar and pestle from the kitchen. Any ideas?
PS: If anybody else decides to try this; Do NOT grind up leaded solder, the dust would be extremely hazardous. Non-leaded solder might also be bad for you, but lead is the worst.