This Hot Air Soldering video (for a $5 syringe of solder paste) makes it look so easy. May I ask if anyone has used and can recommend one of the many $20-$30 Hot Air guns sold on AliExpress, please?

TIA. Cheerful regards, Mike, K8LH

Yes, they make it look so easy.

I tried many times and did not mastered it yet. Sometimes I suceed, sometimes not so well.

Making video, I will select those best attempts, it would be not such elegant as this video, but with good results. I will throw out all those, where there many small balls everywhere, bridges between legs, legs not connected, resistors went flow away from pads, sticked into the air and such. For video it is not problem, but for my purposes it all needed a lot of repairs.

It is good technique, but achieving perfection is not so easy.

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My experience is similar to that but I would add a few caveats:

• It looks rather as if the board(s) in those examples were already heated - they melt suspiciously quickly
• Use of the solder paste is essential (along with clean PCBs) - the flux in the paste really makes the difference. As I'm not commercial, I use a tin-lead solder paste, somewhat lower melting point.
• You will probably want the lowest flow rate and the widest nozzle on the hot air gun, otherwise you will simply blow the parts off the board.
• For larger parts with lots of legs, again, the widest nozzle lets you heat all the part at once, otherwise you can end up with only some of the legs actually where you want them.
• Clean PCBs, with solder mask. Without that, forget it...
• In an ideal world, you'd want to use a solder positioning mask and only put the paste on the pads. The syringes aren't that controllable, usually, for small pads and so far I have had success running a bead along a group of pads, but I have not yet done any particularly small pads - 0.2mm on 0.5mm centres, e.g. LQFP - except once as a trial. Which worked, but too much solder paste will be an issue.

I'm using this method on my SOIC/DIP protoboard to mount the SOIC parts and the 0603 capacitors.

Neil

I have used this method to solder SMD components for some time already. I've managed to solderi without much issue :

- SOIC (50 mils / 1.27mm pitch)
- TSSOP (25 mils / 0.65mm pitch)
- 0603 resistor/capacitor
- QFN (15 mils / 0.4mm pitch)

As said before. Low airflow, very clean board and preheated board. It takes some time, but results are usually good. My solder paste, flux, and heat gun are sourced from Aliexpress, so quality is not the best.

A small amount of rework is needed afterwards, but nothing too complicated.

If you want to watch some "hobby" level hot-air work at a tiny scale, then I can recomend you have a look at this video:

https://www.youtube.com/watch?v=CHoGIvOi-jw

and then this one where he re-works more of it:

https://www.youtube.com/watch?v=p-q8mrZ7V68

Note: The 0201 LEDs he's using are 0.65mm long.

-Gordon

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Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/

I can hand solder 0402, but 0201, whew!

I've tried hot air soldering of BGA, but not very successful; only 1 working out of 4 tries. I think the BGA got overheated by heating from the top while the solder balls is shielded under the BGA package. I think it is important to preheat the board with hot plate while applying hot air from the top.

I recently bought a MPH30, mini hot plate and was successful soldering BGA with it. Got 4 workings out of 4 tries. I believe MPH30 has precise temperature control and heat from bottom where the solder balls are located. This way the BGA package is not overheated.
Bill

I've seen people reworking BGAs with a hotplate and an x-ray machine; they made it look easy. I want one, if I'm ever likely to play with BGA.

Neil

*struggles with the 805 caps....* o_O

Been considering getting a hot air station and hot plate for doing some SMD stuff; trying to sift through all the options.