How To Solder
Soldering is not difficult if you have the right tools. I remember when I first started to solder I was using a radio shack 15 watt soldering iron with super thick silver solder. I thought that soldering must be incredibly hard based on those first attempts. Soldering is actually quite easy and satisfying when you know what your doing.
The Soldering Iron
Firstly, the soldering iron is going to be one of the more important tools you own for dealing with electronics. Soldering irons come in a few different types. The most common are the ones that plug right into the wall and usually have a switch to choose either 15 watts or 30 watts. These are fine for guitar electronics in my opinion, although, a lot of people say that if you want to get into electronics then you really should get a proper soldering iron which has a base that the iron plugs into and has variable heat settings. I have both types and I often end up using the cheap 30 watt soldering iron when I need to pack up and solder somewhere other than my work bench. The down side of cheap irons is that the heads often wear out or loose heat conductivity fairly quickly. They also can take ages to heat up and come with soldering tips which aren't very well suited for more detailed soldering work. The benefits of a proper soldering station (as they are often called) are variable temperature settings, very fast start up time, handle doesn't heat up and internal circuitry to compensate for when you are soldering to large metal surfaces like the back of a potentiometer, which acts like heat sink. The potentiometers case will conduct the heat away from the tip of the soldering iron very quickly. The result is that you end up holding the soldering iron to the pot for ages waiting for it to heat up enough to accept the solder (the cheap 30 watt irons really struggle when soldering to large pots). When you get a new soldering iron you should tin the head. This means that before you use it in your first project you should allow the iron to fully heat up and then apply the solder to the tip then brush off the excess solder. I'm not exactly sure why this is helps but i've noticed that it really does seem to help especially with the cheapy irons.
After the soldering iron, the most important is the solder itself. These days I only use rosin-core solder. It has a lower tempurature melting point than most of the other kinds of solder and works the best when paired with the cheaper 30 watt soldering irons that are common at hardware stores. Its low melting point makes it easy to work with when dealing with capacitors that can easily be ruined by exposure to high temperatures. Rosin-core solder also behaves better than other solder. Because of the rosin in it, the solder will easily surround the solder joint.
The Third Arm Tool
When I began soldering I also didn't have this tool which is perhaps the most useful tool I have when it comes to guitar electronics. This is often called a third arm tool but it really works as a third and fourth arm. It's really the difference between pulling your hair out after 5 minutes of trying to solder the same two wires together and having the same two wires together in 10 seconds with a much better connection. With soldering you really need four hands. Two for holding the two wires together, one for the iron and one for the solder. I can not stress how helpful this tool can be. If you are just gettig into soldering, get this tool! You will not regret it.
Another tool specific to soldering that I use quite often is a solder-sucker. These are basically just little hand pumped vacuums that you use if you want to remove solder from a connection. If you are trying to salvage electronic components then this tool is really necessary. I also prefer the cheapest version of this tool which is just a little red balloon that you squeeze. You then put its nozzle to the re-heated solder and it will suck it up when you release the squeeze. The more expensive solder suckers are spring loaded and you have to set the spring everytime which requires both hands. The squeeze-suckers just require one hand to operate and are generally faster to use. With all solder suckers, you have to clean out the nozzle after a few uses because the solder will re-harden in the nozzle.
This is a tool that is really handy when it comes to checking your work or trouble shooting. Although it is not really necessary in the construction and soldering phases of guitar electronics, when you finish a project and it does not work, you will want this tool to check the connections and see where the problem is. Its also helpful for checking if guitar pickups are showing the correct resistance for each coil. I have even used it to check the wiring of a series/parallel switch. I was sure it worked before plugging in and playing because the resistance values of the pickups combined showed what I expected. This is a great tool for checking the conductivity of a wire and for double checking certain pickup wirings.
This is used to clean the parts that are about to be soldered. Steel wool is my favorite but sand paper works fine as well.
These are necessary to cut and strip wires for soldering.
Preparing The Iron
The first thing to do is dampen the sponge that came with the iron under water, while the soldering iron heats up, and then squeeze most of the water back out. The damp sponge will be used to clean the tip of the iron after every use. This is important because the soldering irons tip will not heat up properly otherwise. As I mentioned above, if you have a new soldering iron, before using it to solder, let the iron fully heat up (about 5 minutes) and then lightly touch the solder to the tip of the iron (only on the part of the tip you plan on using). This prepares the soldering iron for use. After that pass the tip of the iron over the sponge to remove the solder. The soldering iron is now tinned and ready for use.
A Clean Connection
The most important thing when it comes to good soldering, besides the right equipment, is having clean wires and components. By clean, I mean having made sure there are not any finger oils or any impurities on the part of the wire or component that you are about to solder. I always clean the parts of the wire or components that I am about to solder with steel wool or sand paper. This ensures that I end up with a strong, conductive connection. If the parts to be soldered are clean the solder should effortlessly absorb in and around the parts. If the parts were not properly cleaned then there is a good chance that the solder joint will be cold (cold being the opposite of hot or conductive).
How To Solder
The first step after cleaning the leads to be soldered is to use the third arm tool to line up the two things to be soldered together. Assuming the two things are wire, they should be resting right next to each other in a way that the solder can easily join them. Next, get the solder ready in one hand and in the other hand heat up the wire by touching the tip if the iron to the part of the wires. It should not take long. About three seconds after applying the soldering iron, apply the solder right next to the tip and it should melt right between the wires. A sign of a good connection is when the solder melts from touching the wire rather than the soldering iron itself because it means the wires were hot enough to ensure a conductive connection.
An Example Of A Good Solder Joint
Testing The Connection
When just getting started with soldering it might be a good idea to test the conductivity of the newly soldered connection. After a few tries with soldering you will start to intuitively sense when the soldering joint has been done properly and you will not have the need to test it. When starting out though it is a good check step to make sure you are doing everything right. To check your work you will need a multimeter. You set the multimeter to measure resistance (does not matter which resistance setting as long as the knob is turned to the "ohms" section of the multimeter. The meter will show "0L." if there is no electrical connection. If there is a an electrical (conductive) connection it should show numbers bouncing around until it settles on "0.00". This means that there is a connection (the zero means that there is not any resistance). So, to test the connection, simply touch one probe of the multimeter to the one side of the newly soldered connection and the other probe on the other side of the connection. If you see "0.00" on the mulitmeters screen then you know the connection is fine. If you see "0L." which should already be displayed, then the connection is not conductive and is no good.