I wanted to get an idea of the precision required to dispense tiny amounts of solder paste. Unfortunately, my local ironmonger doesn't sell precision hardware!
By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
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There is absolutely no need to use solder paste in your case. It is just absolute PITA.
I use flux paste or pen and regular solder wire. Drag a little bit of solder on all pads. Put more flux paste. Place your part. Touch each pin with a chisel tip until the solder wicks onto pin. Ideally touch pin and pad at the same time.
The only reason to use solder paste is if you plan to place multiple parts and bake it in the oven or with hot air. As I don't have an oven and my hot air technique isn't the best (smaller parts tend to fly out or move) I got rid of the paste (after it gone bad — good riddance) and I have one strange item less in my fridge (less curious questions from family).
I would learn to drag solder but I am too lazy.
Now something like that is available on AliExpress under the name "Aluminum Alloy Rotary Solder Paste Booster" for < 10USD. Thanks Julian for the inspiration.
Hello,
in order to skip this problem, here is another way : put whatever amount of solder paste, enough to fill the pads area, without worry for shorts. I use a soldering hot air gun to melt the paste, but it works similar with an iron. Once you have your thing soldered, remove the excess solder with solder wick and an iron. I managed to solder a really really tiny chip this way, and the chip is nearly as big as the tip of my iron. the solder joints looks perfect, and i have no shorts.
Simply try to keep the paste out of the underside area of the chip (in that case, it can stay stuck there with nowhere to go, and create shorts).
So for DIP chips, simply apply paste on each strip of pads, put the chip, remove excess.
Same for QFN, etc…
…a step
-backward-just go to a hardware store or a vet supply place and get a plunger and thick needle that fits (grind the sharp point off) and there you go! I have done this a few years back–it works! Later I moved to just buying the hypo and filling it–now I just use the ready-made type.I think the "pros" use stencils you can drop any old blob and let a squeegee push the paste through the correctly spaced and sized holes. Plenty of examples of using them on YT. Available on e-bay, but mostly for the infernal iPhone, close inspection shows some likely options lurking in amongst the completely useless ones.
If it's to be squeeze and hope, you need to reduce the nozzle down to a hair's width. Either buy blunt needle dispenser on eBay or I find handwash, cleaning sprays and empty ball pens a good source of reusable fine tubing nozzles and connectors for making such things.
Or just replace the cap and poke a small hole in the end!
Clever idea.
You should store that in the fridge, SMD paste has a short shelf life before it goes hard.
jist drill a tiny hole in the red plug
Looks like a cross between MacGyver and the Fallout games! Fun watching the thought process. Overkill? Maybe. But then again there are probably premade boards out there somewhere
_______Drag Solder__________
In fact, the industrial dispensers use a needle piston, which give a precision of a fraction of mg for each dot.