Ask HN: Resources to get good at soldering?

think of soldering as a thermodynamic and metallurgical system to create a solid mechanical/electrical joint - so while welding is a good analogy, it doesn't really give you a good model on what is going on. to get really good at soldering is to get good at understanding the interplay of the factors involved and then predict/manage them.

fundamental to all this is to recognize that the solder is an alloy with eutectic property -- unlike regular metals/alloys, solder doesn't slowly get mushy and then become a molten liquid; instead, at a precise (band) of temp, it just melts, and then when heat is removed/lowered it instantly solidifies. that is why controlling tip temp is critical first step.

second is the thermal mass of the soldering surface; usb/ethernet connectors have higher thermal mass so to achieve eutectic, you need a beefier tip that can deliver, not a thinner tip and holding it longer; higher than normal temps helps here. for smd led, the opposite applies;

third, is the concept of wettability -- thermodynamic affinity between the molten solder and the solid metal pad; to form a perfect bond between the metals, they must be clean and free of oxides, and applying flux reduces these oxides. High wettability means the solder eagerly spreads out and adheres to the surface rather than forming isolated droplets. That's the working principle when drag soldering.

then there is angle of solder tip, fine motor control, etc -- those are easy to come by. I am not a technician, and I was able to drag solder a lqfp64 with not a lot of trouble. of course, i hate school of hard knocks, so i spent time learning about the process first.

Suggested reading: https://www.amazon.com/Basic-Soldering-Guide-Alan-Winstanley...

Source: decades-old Lockheed certification for rework on Trident C4 & D5 SLBM G&C boards.

ZEEWEII DSO154Pro to go as cheap as possible for something that is roughly useful

Once you desolder and resolder a full size keyboard multiple times (this is before hot-swap was available), most normal through hole PCB soldering jobs becomes easy.

300C on my TS100 for 63/37 lead (from a cheap brand) for any solder in the past 10 years. No extra flux, clamps or anything, just a wet sponge and an open window (or soldering outside), it sounds very basic but once you know how to solder you can do it anywhere.

For desoldering, a good solder pump will do. If a joint is hard to desolder, add solder and pump it again. You can use solder wick to clean up the hole, or you can just pump it again.

Sure, once you have an actual paying job with disposable income you can get all the nice tools, solder, and all that jazz, but it does not make you better, it just makes it easier.

Though saying that, a Hakko desoldering gun is well worth it - I am still good at using a pump and solder wick, but what a time saver the Hakko is.

I have bought some spare Kester leaded spools in case it gets banned for average the consumer, but nowadays I use lead-free SAC305 solder. It's safer clean-up, the only downside is that it does not look as cool. Also, definitely use an extractor fan for lead-free, the fumes are from lead-free are meant to be way more toxic than leaded - I get a headache from some whiffs compared to many more from leaded soldering (obviously try not to inhale any in the first place!).