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I have tried soldering together some very simple DIY projects, such as little kits with a few blinking LEDs and a transistor or two. My soldering is terrible and I confess not actually knowing what I'm doing! I get large blobs of solder instead of nice-looking ones, they are brittle and fall off half the time, all the things you would expect with a complete novice. I plan to learn to do it correctly. That's not the question.

The question is to do with equipment. I have a very cheap soldering iron, one that came from Radio Shack maybe 20 years ago and probably cost $10. It came with a roll of solder, which is also 20 years old. I recognize that this equipment -- while certainly not the cause of my poor results -- probably isn't making my life any easier. I'd like to know, is it possible to learn to solder correctly with this equipment? If not, what are good things to look for in an entry-level soldering setup that I can learn with?

  • What wattage is necessary?
  • What kind of solder do I need?
  • What else do I need?
  • How much should I expect to spend?
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    \$\begingroup\$ Those $10 soldering irons are not worth the price. You need a temperature-controlled iron. Hakko and Weller both make good entry-level irons in the $100 range. Solder doesn't go bad over time, though the flux in it might. I would say it's very possible that the poor equipment is the reason you're getting poor results. \$\endgroup\$
    – Hearth
    Dec 17, 2023 at 0:31
  • \$\begingroup\$ It could be your skill, your equipment, your supplies (the solder) or it could be what you are soldering is old and corroded. Or some combination of the four. There are inexpensive temperature-controlled irons these days, and the tips are universally iron plated and last a long time. A $10 uncontrolled soldering iron (that cost RS somewhere between 50 cents and $1) is not going to help at all. \$\endgroup\$ Dec 17, 2023 at 0:46
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    \$\begingroup\$ There’s plenty of YouTube vids to show how to do it. A common beginner mistake is to use the soldering iron to carry the solder to the joint- that’s bad juju! The soldering iron is used to heat the joint and the solder applied to the joint. The soldering iron tip should be clean and when you touch the solder to it, it should melt and give a shiny surface to the tip. You should be able to wipe the tip on a damp sponge and the shiny surface should remain. Then it is ready to solder a joint. The secret is flux. No flux - bad joint. Whilst the flux is in the solder, it burns off fairly quickly. \$\endgroup\$
    – Kartman
    Dec 17, 2023 at 0:49
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    \$\begingroup\$ If a snapshot, snapshot of your attempts, you'd get a much more valuable answer. \$\endgroup\$ Dec 17, 2023 at 0:50
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    \$\begingroup\$ You have to head over to YouTube! \$\endgroup\$ Dec 17, 2023 at 6:53

3 Answers 3

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Good quality soldering requires two key things.

First, the mating surfaces must be hot enough. Almost all soldering irons work well for the most common types of electronics soldering like what you are trying to do, but you can run into trouble when soldering very large copper objects (such as high amperage connectors), or very small and fine pitch things. The large copper objects are hard to solder because they take a very long time to heat up and most people don't wait long enough, or don't have a powerful enough iron for it. Small items are hard to solder for a different reason: the tip of the soldering iron is very large compared to the things being soldered, and it can be difficult to get the solder to stick to the surfaces instead of the iron. You can also have trouble with a corroded or damaged iron tip. This makes it difficult to get heat to flow from the tip to the mating surfaces. New tips are very inexpensive and will help tremendously if your old tips are corroded and/or the protective coating is worn off them. Better temperature control of the soldering iron helps to improve the tip longevity, but they all need to be replaced sooner or later.

This brings us to the second and critical piece I expect you are missing. Soldering needs both surfaces to be relatively free of contamination, and solder needs to be induced to want to stick to them. Both of these can be solved using solder flux. Solder flux is a simple chemical that helps with solder adhesion, and also cleans impurities from the mating surfaces (and will somewhat clean the iron tips as well). A little solder flux can also help conduct the heat from the iron tip to the mating surfaces as well. Most solder doesn't normally require flux directly as the "Rosin core" type solder already has a center of flux manufactured directly into the solder wire. The problem is that this small amount of flux burns off very quickly, so if the solder connection doesn't work right away, all the rosin flux is gone and then it's very hard to solder. It is also quite possible that the spool of solder you are using does not have any flux. Older solder, especially RadioShack junk either had no flux, or had so little it didn't count.

You can buy small syringes of solder flux from most electronics parts suppliers. Digikey has tons of them like this: https://www.digikey.com/en/products/detail/chip-quik-inc/SMD291NL/1160000 . Any time you're having trouble getting a solder connection to work, add a small drop of this stuff. This will also work miracles if you accidentally solder two neighboring pins together. Add a drop of flux, and touch your iron to it. The solder joining the two pins will often separate out from each other after a few seconds.

One last note, using solder flux is a little messy. The best way to clean it up is with rubbing alcohol. Add some to a piece of paper towel and you can clean the excess flux back off without much effort.

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What wattage is necessary?

Doesn't really matter unless you do professional soldering. What you need is a temperature controlled iron. A good beginner temperature is somewhere between 250-300°C. Professionals tend to use 350°C.

What kind of solder do I need?

Go for "rosin core no clean flux" solder, those exact words. If you can also get your hands on 60/40 tin lead solder, then that's highly recommended for beginners (ok for hobby projects but not for commercial), since it is much easier to solder with leaded solder.

What else do I need?

Flat nose pliers, copper wire cutter, tweezers, a solder wick braid would be the bare minimum. External flux like a flux pen is highly recommended. Isopropyl for cleaning.

How much should I expect to spend?

Depends entirely on what kind of quality you are looking for. For a modern "cartridge" type of soldering iron, Hakko and Weller are well-known affordable brands. Professionals use Metcal or JBC. Big fan of Metcal myself, if you can afford the simplest entry level iron in their product range, it will be still be superior to for example Hakko "premium" models - I'm using both since many years back, Hakko doesn't even play in the same league.

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What wattage is necessary?

Depends on the size of things you're soldering. I still use an old Antex 15W iron, and it's fine for small components. Less so for large terminals.

What kind of solder do I need?

Flux-cored lead solder is the easiest for hobby work. If the components are clean, it should work with no extra flux needed.

What else do I need?

You generally need 3 or 4 hands to do soldering. Unless you have an assistant handy, that means some other way of holding the things you're soldering. You can buy "helping hands" gadgets to do that, or improvise.

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