Soldering Tutorial

Soldering Tutorial

This is intended for people who want to repair or alter their guitar electronics and have little or no experience in soldering. I have seen a few people updating their guitars recently that have little or no experience with soldering. This will hopefully be a good reference for them.

Author’s Background

I learned to solder from my father about age 8. He held a job as a quality inspector at one point and had my capability up to military standards by the time I was about age 12. I have had a career in electrical engineering and probably didn’t go more than a few days without needing to solder something myself in my first 20 years. Today, others tend to do that work for me, but I still have home projects that keep my skills active.

What is soldering?

  • Soldering is the joining of two metals together by melting solder between them
  • Soldering is not welding! Welding is different because you are joining the two materials together by melting the material itself

What is Solder

  • Solder, for our use in guitar electronics, is commonly a tin-lead (SnPb) alloy, SAC alloy which is tin-silver-copper (SnAgCu), or “lead-free” which is tin-copper-nickel (SnCuNi). Tin-lead is easiest to work with but many countries have started to ban the use of it due to the lead.
  • Most solder will come as a spool looking like wire and will have a core of “flux” that will help clean the surface of the metals and improve the quality of the solder joint.

Required Items

  • Soldering Iron

    • There are several styles, but the easiest to use is a “pencil” style. I see these available at Amazon for $15 to $50. Some have temperature control but that is not likely necessary for guitar work.

      • Image is of my soldering iron. It is about 40 years old now. It has a place to hold the cleaning sponge and some tips of different sizes.
    • The tip is an important part of the iron. Too small and there will not be enough heat to warm up the parts to be joined, and too large will overheat the parts and possibly melt or burn things you don’t want to. The third tip from the left has a flat edge to it that I didn’t get in the image. It is maybe 1/3 of the far right tip width and is a pretty good size for our purposes.

  • Cleaning Sponge

    • A damp natural sponge is a common cleaning tool. It removes excess solder from the tip and can be used as a cooling surface for small things or tips if you need to change the size.
    • An alternative can be a damp paper shop towel. It doesn’t last more than a few uses, but it is something you may have around the house. I have used regular kitchen paper towels, but they do not hold together very well.
  • Solder

    • Solder will come in different diameters. I recommend for guitar purposes, using something around 0.025-0.030 inches (0.63-0.76mm). Smaller will help with not using too much but cause you to use more length of the spool. Larger will be a little harder to control the amount applied to the joint.

    • Flux type is not a major choice. If you can use tin-lead, the the rosin flux will be the easiest to work with. Some need to be cleaned off, some can be cleaned with a water-damp swab. Read recommendations if you go with something other than rosin. I personally have only used non-rosin flux in the workplace and simply used the cleaning solvents supplied to me. Joints always look less shiny.

    • The length I’d need to replace a volume pot would probably be less than width of my first two fingers. If you are doing this for the first time, you will probably use a bit more. You won’t need to buy a full 1-pound spool. It is commonly sold in small tubes for about 1/10th the price of a big spool (around $6-$8 USD vs $40-$60)

  • Solder Wick

    • This is maybe not required, but will make your work far easier. It is a copper braid with a little flux on it that soaks up excess solder. It is invaluable for unsoldering and cleaning up old solder on a joint.
    • “solder wick” may be a trade name, but you can find the product in web searches by other brands using that name

Useful Items

  • Heat resistant work surface or cover for the guitar and table
  • Vice, clips, or some heat resistant holder

Soldering Iron Care

  • Keep the tip ‘tinned’
    • Maintaining the coating of solder on the tip will retain its ability to transfer heat. The coating also acts as protective layer against oxidation. Always tin the tip with a little solder when you set the iron down for a moment or more.
    • Only tin the working surface of the tip
    • I make sure there is a good layer of solder on my tips when I turn the iron off for storage

Soldering

Solder is intended to flow between the parts to be joined. This means that you need to heat both parts simultaneously and then apply enough solder to fill in the gaps and hold the parts together.
Too much heat and you will melt or burn insulation, or even oxidize solder lugs on parts making them impossible to join.
Too little heat and solder will not flow well and may not adhere to the surfaces. If the solder did not spread out a little, there may have been too little heat applied.
Keep the flux freshly applied by dabbing the solder onto the soldered surface if looks dull or poorly flowed.

  • Procedure
    1. Turn on the iron and wet the cleaning sponge with water
    2. Test tip temperature by trying to melt a little solder on the tip. It should melt immediately.
    3. Put the two items to join together and make sure they will stay in place when touched by a soldering iron tip
    4. Clean off the solder from the tip on the sponge and re-tin slightly
    5. Press the tip simultaneously to both items being soldered
    6. Press solder at a point that is both at the tip and on one of the items. This should melt solder and help spread heat across the joint enough to let solder flow
    7. Lift the solder and tip off the joint
    8. re-tin the tip

That is really all there is to it. If you want practice, use some wire ends, twisted together, to get a feel for the timing and amount of solder.

Thoughts From Experience

  • De-soldering something takes some work. In many cases, you can just add a little solder to heat the whole joint and then separate the pieces with tweezers to hold one of them. Sometimes it takes using the wick to clean most of the solder first, then freshen the joint so it is completely melted and then separate it. Often, adding solder helps get the wick to warm enough to start pulling the excess off the joint. It is usually just a really quick tap of the solder at the tip-to-wick point to get it started. You will want to remove enough solder to separate the part/wire with tweezers and then let them cool.

  • Removing soldered parts will often splash solder. These splashes are hot enough to melt plastic table tops, darken wood, or make pits in a guitar finish. Be sure to protect surfaces that you don’t want melted/burned.

  • If reworking something that has been soldered, clean it first with the wick to remove excess solder. You will have an easier time creating a good joint.

  • When attaching wire to a pot lug, it often may seem useful to twist the wire to hold it in place. Reworking this later will be very difficult since you can never really get all the solder off. I recommend a simple bend or holding the wire in place somehow so that you get a lot of the surface of the wire on a lot of the lug.

  • Do not put solder in your mouth. It is poisonous. If you need three hands, even with things fixtured in place, then wrap the solder around your thumb with a little sticking straight out so you can place it in the desired position.

  • Wash your hands after handling the solder (especially the leaded variety). If you smoke, be sure to clean your hands before touching the cigarette. Burning the lead that was just wiped off onto the cigarette and then inhaling the fumes is not a good idea.

  • If you want to mix leaded and lead-free solders, for instance doing a rework, it is ok. I recommend that you clean off the old solder as well as possible.

  • Most flux we will see does not require cleaning. I have rosin flux on electronics that is decades old and it didn’t cause any corrosion.

    • some solder flux can be cleaned with water, some (rosin for instance) will need isopropyl (rubbing) alcohol. Use a cotton swab for this. Alcohol can dissolve some wood finishes and plastics. Control where it is allowed to go.

Examples

  • Too much time under heat and not secured
    This has a low luster surface because I had it hot too long and burnt off all the flux allowing some oxidation and I also wiggled it as it cooled. Both these errors cause a poor joint.

  • Not enough heat
    This joint didn’t flow well to the pot lug. It may break off easily, and over time may also break off, even buried in the guitar not being wiggled. This was caused by not enough heat applied to BOTH lug and wire at the time the solder flowed. This can be touched up quickly with re-flowing the solder, making sure to touch both wire and lug while quickly touching a little new solder to the joint to add flux to clean up the surfaces.

  • Pretty good joint
    This joint is reliable. The wire was secured without twisting it so it is stationary while cooling, yet easy to de-solder if needed some day. The heat was applied to both pieces evenly and a good amount of solder was used.

26 Likes

Love it! My dad ran a radio and tv repair service and I learnt to solder at an early age, it’s served me well for many years.

Superb tutorial, Michael, warrants so much more than a simple :heart:

Thanks for this detailed tutorial and for taking the time to create that post. For sure it’s helpful for some of the guitar tinkerers here.

Thank you very much for that Michael, it will be very helpful when I come to do mine.

The time and effort you have put into this article is very much appreciated.

One day, I hope I’ll need this :wink:

Thank you so much Michael for all the efforts in sharing your extensive knowledge and the experience you gained. Although at the moment I do not have any needs to apply it, but I’m very much interested to learn these skills. I’ve bookmarked your tutorial, and once I find a bit of time I might get myself a better soldering iron than I currenly have and start practicing.

Could have done with this a few years back when I pimped the Affinity.
I still think my soldering would be better suited to the Forth Road Bridge, hence any reference to welding in my write up.
image

1 Like

A very interesting and informative write up that I’m sure will be of great value to community members.

You could have done a sterling job on the Millennium Bridge.

3 Likes

That’s the one with the built in Whammy Bar isn’t it ? :rofl:

3 Likes

Wow! That’s excellent for people new to soldering.

I don’t have nearly as much experience as @sequences, but I have built an amp and multiple pedals. I would recommend using a brass wool sponge to clean your solder tip. Especially the cheaper solder irons can corrode quite quickly when using a wet sponge. Here’s what the brass wool variety looks like:

brass-wool-solder-tip-cleaner

Those are good for knocking off heavy corrosion/oxidation that the flux won’t do quickly. I have used them in workplaces where folks don’t treat the tips right. I think I also found them useful with some of the lead-free solders.

If you keep the tip tinned well and frequently, you won’t need it. I have one but only used it when I goofed and forgot to tin my tip after wiping it clean, then letting it sit for 10-15 minutes. :person_facepalming:

oh, and NEVER try to sand/file a tip, it has plating that will be removed and become useless.

1 Like

Turns out Weller has a pretty elaborate video on when/how/why to use the brass vs sponge tip cleaner:

They mention exactly what you said, brass is good for lead-free solders. That’s what I was using, which is probably why I ended up liking the brass better. Ultimately it’s all personal preference though!

Now this is exctly what I like to see … Someone who knows what they’re doing, imparting their knowledge in a perfectly understandable manner so people can benefit from it. Top post, Michael :+1:

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What a great resource!

It’s nice to see that I’ve been getting it right for the most part, I lean a little heavily on the brass wool vs the damp sponge. I’m going to work on that.