This is an old revision of the document!
Jeff V: “One thing I would like to see is information and tips on how to attach objects to a board that don’t have leads to bend (e.g. ICs). They can be difficult to solder on when they won’t stay on the board!”
Coofer Cat: “I was always taught to clean the soldering iron, then dab a tiny amount of solder onto it. This gives the iron a “liquid edge” which means it touches the pad and the lead with a greater surface, which ensures the heat is transferred (evenly and quickly). In truth, simple joints work either way, but more difficult ones benefit from this technique.
Also, I was taught to look at the shape of the solder join when it’s cold. If the join has a sort of inverted curved pyramid shape around the lead, then it’s good (because the solder has properly wetted the joint), but if it’s sort of a blubous outwardly curved shape, then there’s a good chance the joint is dry (and although it may work now, it’ll probably fail in the future).
Either way, this and the one-page version of it are great guides – thanks!”
Mike says: “A great little starter guide. The use of safety glasses should be stressed more. Banging the board on the table is not recommended. I still have a scar from 40 years ago from doing this.”
Florin: prefer to cut the leads before I solder them - this way there's no risk of unsettling the contact while you cut the soldered lead, so this gives you nice solid reliable contacts. This requires you to hold the component with one finger while you're soldering it (otherwise it may fall off), which may get tricky as the component becomes pretty hot, but with enough kung-fu you'll be able to do it easily (e.g., hold it with the fingernail). I soldered thousands of components this way. Another tip: when in doubt, put a little rosin on the pad and lead before soldering them, even though the alloy is supposed to contain rosin already. Again, this reduces the risk of a poor contact. Never use cheap unstabilized soldering irons - those are only for rough jobs like soldering the lid on a tin can, and then just use the biggest iron you can find. For electronics, only use stabilized (regulated) irons (soldering stations), that allow you to finely tweak the temperature. Working at the right temperature is crucial; too hot and you burn components and oxidize pads before they get soldered; too low and again you may burn components because you're fiddling with the iron too long; or you make weak unreliable contacts. You'll figure it out with experience. I actually prefer to use a soldering gun instead of an iron for anything except very sensitive multi-pin components that don't like EM pulses. Again, it's a bit of kung-fu to know when to push the trigger and when to release it; essentially, your brain becomes the thermal stabilizer. :) You need to “wax on, wax off” many hours before you obtain the skills, but then it's awesome. The gun allows you to do neat tricks like transport large drops of solid rosin, because you heat it up or cool it down instantly, as needed; a station, OTOH, is always at the same temperature. Heating up both lead and pad at the same time is crucial. It bears repeating - crucial. Push the iron or gun against both parts. Don't push too hard, but make sure the thermal contact is good and firm. Whether you wait 1 second before touching the heated pad+lead with the alloy, or you don't wait, depends on the technique. Whether you wait 1 more second before you retract the iron, or you don't wait, again depends on the technique. But once the liquid alloy has spread out, pull the iron at once, don't tarry. Then blow air over the hot area. Nail clippers work just fine for cutting leads. Sometimes you don't want to solder components too close to the PCB. This is true for those resistors, transistors, etc. that dissipate a lot of heat while working. Give them some breathing room. In general, don't push 3-pin components (such as transistors) too close to the PCB; when they begin to resist, you need to stop pushing. But soldering them might be tricky if they're not sitting stable in that position. All that stuff about toxic metals and rosin fumes - I should probably be a brain dead zombie by now, I never washed my hands afterwards. Rosin smells kind of nice actually, similar to incense, but breathing the smoke directly is not pleasant; I doubt the smoke is more toxic than any other kind of smoke. Finally: 2 hands are sometimes not enough. It helps if you're an octopus.“
drblast: ”“Then blow air over the hot area.” I'm no expert, but I've always heard this is a bad idea. (A “cold solder joint”)
gambie: One thing that's rarely mentioned in soldering tutorials is temperature. With good temperature-controlled soldering stations like the Weller WES51 available for <$100, I'd be hard-pressed to recommend skimping on a cheap pencil iron. Trouble is, I've seen very little discussion about what temperatures to use for particular types of solder.
Yeah, I cringed at that part too. the part about banging the board on the table to remove solder The trick with desoldering is that sometimes you need to add more solder before you can remove it. If a joint won't desolder, the easiest solution is to add a bit more solder until it balls up, then suck it all away with a spring-loaded solder pump. I find desoldering braid a bit tricker, but the secret there is to prime the braid with a bit of solder to improve heat transfer before holding it to the joint.
Natsu: There's no mention of using desoldering braid (or even the suction bulbs) to fix bad joints? Sorry, but I don't like the “whack the circuit board on the table” method. Once you get used to doing it right, desoldering braid is awesome. I never did get the hang of those squeeze bulbs, though. The braid was always so much easier to use.
I wouldn't complain if they didn't mention desoldering at all. But they do mention it and they only give one method for it, as if that's the only way to do it! I've actually done more desoldering than soldering and I would have gone crazy if I had tried to do it that way. I find braid to be the easiest method by far, but that's just personal preference. I'm sure there are people other than me who can get the suction devices to work well and who don't have to buy braid all the time.
iigs: Neat comic. My opinion differs on soldering irons. I find that cheap electric soldering pens tend to give me poor results. For someone starting out I think this could be discouraging. Radio shack has a cheap butane pen that works much better for me. It does cost slightly more, but I find it is usable on a wider range of projects and can even heat shrink tube in a pinch.
cypherpunks: Issues: 1) The solder should always be convex, not concave. It's not that way in the illustrations. A concave ball, as sometimes shown, may be a good connection to the pad, but a cold joint to the wire. It'll work, for a bit, but may eventually fail. 2) Always, always, always keep the tip tinned (covered with a thin layer of solder). The solder acts as a thermal conductor between the iron and the joint, which lets the joint heat up much more quickly. It also prevents the iron from oxidizing. If you don't do this, the iron will oxidize, and you will no longer be able to tin it. 3) Feed the solder into the joint, not into the iron. That tells you the joint is hot enough. 4) Temperature controlled iron makes a huge difference. Weller WES51 is the minimum you should use ($90 or so). More expensive irons in the Weller line don't make a big difference. Metcals are nicer, but wicked expensive.
lell: Interesting comic. I was thinking about giving it to my kids, but it gets a bit too complicated starting on page 4. And there are no simple examples. It would be nicer as a longer series that explained how to make some simple circuits in the same down to earth tone.
chaffneue: It's a fun guide, but a couple of things irk me. Bending the leads out is a serious no-no - makes it very hard to desolder the component. if there are a lot of components, it' better to solder them in by height, so you can allow tricky parts like diodes, resistors and inductors to rest face down on the table/workstation pad. I think that the things sticking out of ics and semiconductors are usually “pins” not leads. Banging a board on the table can chip the board or get you burned by molten metal… it's better for the entire job to clean the pads of solder with a vacuum tool or desolder braid. Holding your hand over the excess while side cutting is going to hurt and having slivers of tin, copper, nickel and lead in your palm ain't worth it. They should have also had a little aside about wattage as starting with a 45 watt pencil iron is going to suck.