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I am looking to get into hobbyist, "casual" electronics work, and I am concerned about which type of solder I should look at - I don't have any current plans for going to PCBs, just mainly breadboard and loose wire types of applications.

I have some questions:

  1. I am used to a thicker solder (maybe 1.5-2mm) from courses in school, but everywhere seems to recommend thinner for tighter areas. However, I am starting with just loose wires and terminals on components, so is thickness that vital? Would the thicker solder still cause issues?
  2. On Digikey (mainly used right now to get an idea, to figure out model numbers and such,) they have Kester Solder brand wire, two of which are 24-6337-8814 and 24-6337-7614. The first is part of the 245 series, while the second is part of the 275 series. Would either of these be sufficient for what I have planned?
  3. Is any cleaning required for my chosen application, namely wire to wire and wire to terminal on motors and sensors and such?
  4. In the future, if I DO expand into PCBs and maybe even surface mount, would the 8814 model number above, as an example, still work fine without needing to clean the board? I am trying to minimize the hassle of this, so I am trying to find a solution which is most streamlined.
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  • \$\begingroup\$ I always clean boards after I solder them. I find high purity (90 or 99 percent) isopropyl alcohol works best for cleaning. Some people don't bother, but I don't like to leave a residue. Make sure you use solder that is intended for electrical applications. Also, use some no-clean flux. Flux is indispensable when soldering. The solder and flux used by plumbers to solder copper pipe is corrosive and will definitely ruin thin wires or PCB's over time by causing corrosion. So make sure you use electrical solder and flux. \$\endgroup\$ – mkeith Dec 13 '20 at 9:09
  • \$\begingroup\$ So wait, even though the solder has a rosin core, I still need to add more? \$\endgroup\$ – chronotides Dec 13 '20 at 9:17
  • \$\begingroup\$ Use 60-40 lead-tin solder. Lead free solder is notionally safer, but not vastly safer if at all in practice, and much harder for beginners to use well. \$\endgroup\$ – Russell McMahon Dec 13 '20 at 9:17
  • \$\begingroup\$ Thanks. If I get solder with a rosin core, do I need extra flux, even if it is no-clean? \$\endgroup\$ – chronotides Dec 13 '20 at 9:29
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    \$\begingroup\$ If you get solder with rosin core, no you do not need to add more rosin. You could go your whole life doing hobby stuff and never need it. \$\endgroup\$ – Kyle B Dec 13 '20 at 10:22
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I am used to a thicker solder (maybe 1.5-2mm) from courses in school, but everywhere seems to recommend thinner for tighter areas. However, I am starting with just loose wires and terminals on components, so is thickness that vital? Would the thicker solder still cause issues?

I agree with @KyleB, some 1.5 mm diameter totally works, and it's what I used for years, though I now prefer much much thinner solder (0.5mm diameter). But it really makes little difference to the joint; all that matters is that you're able to supply a appropriate amount of solder. That's more a question of manual precision than diameter, though lower diameter can make things easier, but some find thinner solder harder to handle, so start somewhere. If you feel like it would be easier to get a different diameter because you're regularly running into the problem of having too much solder on your joint or having to feed an annoying length of solder into each joint, then go for it.

The act of soldering is a craft. Even though I've been soldering for about 28 years now, I'll never be as good as the Electronics Technicians I know (that's a proper occupation, actually a family thereof, with a formal 3-years education here in Germany); so I just pick what works best for me, and so should you: start reasonable (not the cheapest soldering iron, electronics solder somewhere between 0.5 and 2mm in diameter), and buy wire as you need it.

On Digikey (mainly used right now to get an idea, to figure out model numbers and such,) they have Kester Solder brand wire, two of which are 24-6337-8814 and 24-6337-7614. The first is part of the 245 series, while the second is part of the 275 series. Would either of these be sufficient for what I have planned?

Buying USD 42 worth of solder seems like proper overkill at this point. Unless you're starting to solder jumper cables, a single solder joint will need less than 0.1 g of solder, once you've got the hang of it¹. I'd rather buy a smaller amount of less industrial-quality solder – so you have a realistic chance to last longer personally than your roll, and you get to try a different diameter, or chemical composition, if you want, later on.

Anyways, yes, these two are high-quality electronics solders, and one of them is even lead-free. Although lead-free solder has the reputation to be harder to use manually, I don't actually think that'll be very relevant to your use case. Both have exactly the same melting point, and that's a low one, too, so they are both equally easy to get to flow.

Health-wise, the lead-free option is certainly nicer, but, honestly, the trick is not breathing in eather solder's fumes, no matter how little or much lead is in there.

Is any cleaning required for my chosen application, namely wire to wire and wire to terminal on motors and sensors and such?

No. It might look nicer.

In the future, if I DO expand into PCBs and maybe even surface mount, would the 8814 model number above, as an example, still work fine without needing to clean the board?

Usually yes.

I am trying to minimize the hassle of this, so I am trying to find a solution which is most streamlined.

Then don't overthink it now. You're not going to solder SMD tomorrow, and the moment you do, you will be ordering these components anywhere that also has more solder – when you need it. No need to stockpile.


¹ I'm trying to guesstimate what I use per through-hole pin on a PCB, by my past consumption, right now, and right now I think I'm at about 0.0094 g, so that your 450g for 40 $ would last me about 47,800 solder joints. That is more than I plan to do in a lifetime; I don't solder for a living.

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Here's a nice video.

Personally, I find "special for SMD" 0.5mm solder annoying as the wire is too frail and bends in funny ways, plus when I need a bit more of it I have to feed quite a long length which means fingers get closer to the tip of the iron. 1-1.5mm solder is fine for pretty much everything ; 1.5mm is more convenient for thru hole and 1mm is more convenient for SMD. 2mm is too thick for SMD resistors and such.

As far as composition, Sn63Pb37 is fine.

Flux is important, get a no-clean flux that isn't corrosive (like rosin) ; if it isn't no-clean then it'll probably be corrosive and you'll have to clean it. And you can't really do that on female connectors because the isopropyl alcohol will deposit some flux residue inside the connector and then it's impossible to get it out. Same for potentiometers or anything that isn't cleanable.

An important aspect of flux is smell. Some are really bad, others are more tolerable. Don't buy a $40 roll of solder, buy a small one first and check how bad it smells, see if it works for you. Most solders will work just fine, no need to overthink it.

Also a nice thing to have is some flux, and a soldering iron that heats quickly and accurately, with the correct tip (ie, bevel or screwdriver). A 2mm screwdriver style tip is really versatile and has much better heat transfer than a "rounded point" tip.

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