Wiring / Soldering

Wiring and Soldering Tips

This particular page is provided as a guide if you are not familiar with soldering small electronics. I have been soldering long before I started playing guitar. I have found doing my own soldering work on my guitars has provided good practice for this skill. If you want to attempt it yourself I will explain the process of soldering.

A medium wattage plug in soldering iron is fine, or even a small butane, which I prefer. The type of solder that you use is somewhat up to you. The 60/40 rosin-core solder is a pretty standard choice, but for my custom guitar project I chose 62/36/2 silver bearing rosin-core solder. I chose this type of solder for a few reasons. One reason is this type of solder is eutectic, which means it melts and solidifies at a specific temperature. A solder joint hardens very instantly with this type of solder, instead of hardening slowly and possibly causing a “dry” solder joint if you allow the parts you are soldering to move slightly before it hardens.. A dry solder joint is a solder connection that is physically holding, but has poor conductivity between the two conductors that it is connecting. Silver is also a better conductor than the usual tin/lead mix, but you can use a solder with a higher amount of silver for more significant conductivity. I have used 60/40, tin/lead, solder widely, but found the silver bearing solder hardened instantly, so I didn’t have to hold a part still for as long. The connections appeared to be more shiny and stronger than 60/40 as well.

The conductivity improvement is also argued with silver bearing solder. With my ohm meter I checked the resistance of my ground connections, and the silver bearing solder didn’t seem to add much resistance to the connections compared to other solder types. If you factor the conductivity rating to the amount of each metal in silver bearing solder you will find that the 2% or silver actually increased the conductance 15%. This was found by multiplying the percentage of each metal by the conductivity getting 1.242 (Silver), 5.39 (Tin), and 1.692 (Lead). You divide Silver, 1.242, by the total of all three, and you find that silver accounts for just under 15% of the total conductivity. It doesn’t take much silver to make an improvement, but you will find better kinds of silver bearing solder than 2%.

With soldering it is also important to use flux. Flux is a substance that prevents the oxidation of metals, and decreases the surface tension of the solder. This causes the solder to soak into the connection quickly, and keeps the surface oxidation from contaminating the bond. In my wiring I have also found that dabbing a small amount of rosin flux to the connection before it is soldered is a necessity. The use of flux is also argued in the use of guitar wiring from different information you can find. Some say that the flux is a very corrosive chemical that can damage components and should not be used. They are referring to acid flux, and I wouldn’t even consider using it. The rosin flux that is sold as a soldering aid, however, is the same rosin that is contained in the core of traditional solder. It can be nasty stuff too, but when used sparingly makes soldering connections very clean and quick.

The goal of soldering a connection is to make a clean, highly conductive point where conductive terminals of wires and components meet all without applying too much heat for too long and damaging components. The first step is to first preheat the soldering iron and wetting a small sponge. Before anything is soldered the tip of the iron is "tinned" by melting solder directly on the tip and then wiping it of with the wet sponge. After this is done the tip of the iron is very shiny and silver in color and is ready for use. It is best to tin the soldering iron frequently while soldering to clean the black film, that accumulates, off of it. When applying solder you can meet the solder to the irons tip as it touches the connection to be soldered. You can also apply solder to the tip before touching the connection to free your other hand or even to tin the tips of the small wires that you will use.

A heat sink should also be used if you are going to apply the iron for a good amount of time, or if the component is getting too hot and is still not soldered. You can buy heat sinks or even use small alligator clips. This heat sink is clipped to the same side of the lead where heat is applied giving the heat a different conductive path and taking some of the heat off of the component that you are soldering. In most cases with my own wiring, by using a dab of rosin, I only touch the component for a count of two seconds at the most an then take the iron off. I then wait for the spot to cool off a little then hit it with the iron again until a good solder joint is made. Two hits of the iron is all it usually takes for the really small connections.

It is also very important that the connection doesn't move at all during the cool off period causing a dry solder joint. You can tell if this happens easily by observing that the solder joint appears a dull silver and not shiny in color. If this happens the connection may not be good or even hold up for a length of time. Sometimes the bond between the solder and connection point lifts away making an intermittent connection. It's best to hit the connection again and hold it very still while it cools to remedy this. Another bad solder joint is a “cold” solder joint, which happens when the solder does not heat up enough when the iron is applied. The cold soldering joint also has a dull appearance. If the soldering point isn’t shiny it is safe to assume the connection is bad and try again. This is much easier than trying to hunt down the bad connection later.

You may also find that you have applied too much solder to a point and you need to get some of it off. There are several different de-soldering pumps you can get or what I prefer is using a de-soldering braid. This braid is infused with flux and when the iron is pressed on it solder starts to soak up into it. The concept of dabbing rosin flux on the connection to be soldered is the same. The flux guides the molten solder evenly into the connection with minimal heat contact. I have even found it very useful to dab a small amount of rosin to a connecting wire after I have twisted it tight. This keeps the tiny wires from straying off and making bad connections when you are trying to push the wire through the small eye of switches and components. I found it very quick and easy to push the wire through this way and bend it firmly onto the terminal before I even hit it with solder. It is also optional but I recommend the use of heat shrink tubing to go over each wire to terminal connection. This ensures that a stray wire can't cause short circuits. I also believe that in the environment of an electric guitar vibration runs rampant through the circuit constantly. The use of heat shrink tubing ensures some vibration absorption and holds the thin fragile wires firmly in place. I prefer a butane soldering iron, since the heat gun, which shrinks the tube, is built into its function. Most of the time I use the exhaust of the soldering iron as a heat gun, or switch to the heat gun tip for the iron.

This is the best way to solder two wires together, and of course using tape or a heat shrink tube over the bare wire when the connection is finished. With soldering you will always want to keep your mind a few steps ahead of the connections you are currently making. As more and more components occupy the same tight space in a guitar you may make the mistake of blocking your own ability to have clear access to the next connection point. The soldering iron is very hot, and it will scorch anything that it touches , so it is best to keep the soldering points as open as possible. My custom guitar was a bigger challenge to me than most modifications that I had done before. There are many components that take up a great deal of real estate in the wiring box. All of the components and wiring were deliberately positioned as the circuit was built from the bottom up. I checked the amount of space components took up by just loosely grouping them in the space where they would be mounted. If the wiring is complicated, this method will ensure that everything will fit. There will be no surprises that will get you stuck, and having to take a step backward. For my custom guitar I had to stack some components just so I could have easier access to the next point to solder, and so they could all fit into a small space.

This is a Heat-Sink in use. When the hot soldering iron is applied to the component’s wire, a portion of the heat that is traveling toward the component gets transferred to the Heat-Sink. In this case an Alligator clip is used. The more metal, attached to it, the more capacity for it to take the heat instead of the component you are soldering. The heat sink isn’t completely necessary if you are on and off the solder point quickly, and allow it to cool off. The funny thing is as you are soldering, the wires, themselves take a portion of the heat. Take care not to scorch them. Just touch the spot for less than two seconds, and let it cool off for a good thirty seconds. Then try again until a good strong connection is made. I usually touch the component each time with my own finger just to be sure. If I cant stand to touch it, then the component is getting too hot and I lay off the iron for a moment.

A mini pliers set, such as this, makes the best kind of tools for wiring small circuits. You may find that you need to hold a wire in a tight spot, or an awkward angle while you are soldering. The small needle nose pliers are good for helping to pull a tiny wire through a terminal before you solder it.

This particular solder kit is what I prefer to use. Everything is stored in one case, and the heavy duty butane soldering iron has multiple solder or heat gun attachments. Highly recommended.

You will find quality solder, solder braid, and solder flux an important part of your solder kit. Silver bearing solder was used in this case instead of typical 60/40 solder. Solder braid has been one of the best ways to remove solder. You can use a solder pump instead, but I found the braid to be quicker, and doesn’t require cleanup. The latest rosin flux that Radio Shack has now is quite a bit different than I had many years ago. It is still very effective, but I remember it having real pine rosin in it, and not all chemicals.

This is solder braid in use. When it is used you use the same amount of heat and time on a spot as you would with solder, so adjacent parts and wires do not get fried. The beauty of solder braid is that it soaks up all excess solder and it is easily cut off and disposed of. So many times I have used a solder pump and I couldn’t locate where the hot blob of solder shot off to, or if it does get inside you have to get all of the solder shrapnel out of the pump, eventually.

I tracked down this spool of cable many years ago at Radio Shack. It is basically a shielded audio cable with four conductors plus ground. I usually strip the cable down and use the color coded wires for all my guitar wiring. The individual wire gauge is the same as the gauge used for the Seymour Duncan pickups that I have used in my designs. This may be the hardest kind of wire to find unless you go to a electronics specialty store. Every basic hardware store is only going to have a thicker individual wire at best. If you do find it get quite a bit extra because you will probably need it down the road.

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