How to solder your connections
  
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What is soldering?

Soldering is the practice of joining metallic parts with "fusible" alloys, usually tin and lead. Note that lead is harmful and even illegal to use in soldering in some states. There are several Lead-Free solders available, please use those instead. Solder is commonly used for connecting wires, LED's, circuit boards, or other electronic components in your vehicle.

Note: You need to use Rosin Core solder, not acid core for soldering your connections.

Soldering Irons:

A typical soldering iron bought from a local hardware store will vary from about $5 to $80 in price, and anywhere from 15W to 100W in power usage. The advantage of using a nicer iron with a higher wattage, is that the iron will heat up the joint you are working on more quickly. This makes the job go much faster, and there is less chance of melting or burning the insulation surrounding the joint you are working on. Sometimes a smaller soldering iron will not work at all for the gauge of wire you are using, however, if you are working with smaller components easily damaged by heat, a smaller iron is necessary (such as LEDs or some circuit boards).

Note that a higher wattage does not necessarily mean the iron runs hotter, it may mean there is more power available for larger joints. Rather, when a soldering iron heats a joint, it is transferring the heat from the tip to the joint. A smaller power rating might mean that the soldering iron will cool down and not be able to transfer heat as long as a higher rated iron.

Soldering:
Before you begin, every part must be clean, this includes the soldering iron tip, and make sure you are working with new wire. If you're trying to work with a very old wiring harness with visible oxidation, spend the money on a new harness. "Dirty" parts do not accept solder. The solder will bubble and fly off the joint, causing more frustration than it's worth. When this happens, a common mistake is to try to apply more heat to the joint. This can melt your insulation, and waste your time, always start off with good clean wire.

Step one: If you are using heat shrink, it is a good idea to place it over one of the wires before doing anything else. Strip the wire back about 1/2" or larger, depending on the size of the wire. (Note: Make sure when you've connected the wires, and go to heat shrink the connection, your length of heat shrink is at least 1/8" to 1/4" over either side of the joint.) Connect the two pieces of wire together by interlocking them as shown in the pictures below, then twisting them together.

Step two: After the iron is hot, the tip must be "tinned", meaning coated with solder. To properly do this, melt some of the solder onto the flattened part of the tip of the iron. Wipe off excess with a damp cloth or sponge so there is a thin layer of solder on the iron tip.

Step three: Apply a little more solder to the tip of the iron, and press it up against the joint (the bottom side of the wires works great). Try to make sure that the small amount of solder on the tip of the iron is seeping up into the connection. If done properly, this should heat both wires in a matter of seconds. Once heated, apply the solder to the point where the soldering tip meets the wires. The solder should melt immediately and flow into the wires. You can move the solder along the wires to let it melt into them. Be sure to get solder along the length of the bare wire, so there is no bare wire left unsoldered.

After the connection is soldered, remove the soldering iron from the connection. Make sure the connection does not move until the solder is cooled down and hardened. The first figure below shows an incorrect solder, the second shows a correctly soldered joint.

Incorrect

 
Correct

Step four: Whatever your method of covering the joint, now is the time to do it. Heat shrink is by far the most common, it can be purchased in our online store here. Other ways to cover your connection are liquid electrical tape (accepted), electrical tape (not generally accepted).

Assuming you've chosen to use heat shrink, and already have it sleeved over one of the wires used in your connection (mentioned in step 1), you'll want to wait until the connection cools to slide it over. When the connection cools, move the heat shrink until it is centered on the connection. Using a heat gun, butane torch, or a cigarette lighter, use steady passes to evenly heat the heat shrink. Do not heat it too much in one place, this could cause it to catch fire, and/or split open leaving your connection open.

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