Soldering 101

Lets face it, there will come a time in your modding career when you will need to solder something. This is not a task that should be taken lightly as it involves high temperatures, molten metal, and dangerous fumes. Not to mention the risk of damaging expensive parts. Why should you solder you say? After all there are plenty of other options to making a connection than fusing two pieces of metal together with molten metal.<!--break--> The upside to soldering is a solid connection that will never fail, and no induction of electrical noise that is sometimes caused by crimp and twist connections. Thankfully with a little guidance and some practice you can become a master at soldering. I hope to provide you the guidance with this tutorial.

The proper tools for the job.

Fig 1: Helping hands, Fig 2: Soldering Iron, Fig 3: Soldering station, Fig 4: Butane soldering torch, Fig 5: Butane soldering iron, Fig 6: Scrap PCB, Fig 7: Small diagonal wire cutters, Fig 8: De-soldering sucker, Fig 9: Tip cleaner / tinner, Fig 10: De-soldering braid, Fig 11: Silver bearing solder, Fig 12: 60/40 rosin core solder, Fig 13: LEDs and Resistor, Fig 14: 18ga wire, Not numbered: Cigarette lighter.

As with most things in life, you will do a better job if you use the proper tools for the job. This most certainly applies to soldering. With out the proper tools you will struggle to make a good solder joint. Lets begin by listing the tools you must have followed by tools that are good to have around.

Must haves:

• Decent soldering iron / station (fig 2 and 3 above): Throw away that $5 iron you bought at the discount store and get an iron with at least 2 temperature ranges. The one listed above is a $20 dual wattage model from Radio Shack. While it is not the best, it will still get the job done. Another thing to look at when buying a soldering iron is replaceable tips. If the iron you have does not have replaceable tips, throw it away and buy one that does. I try to keep 3-4 of each size and style tip I use.
  
• Helping hands (Fig: 1 above): These are just what the name implies. They act as a second set of hands that will hold the things you're soldering on.
  
• Sponge / paper towel(The brown thing in Fig: 3) This is used to clean your tip between joints. Wet it so that its just wet to the touch. I have a paper towel in this image because my sponge is MIA.
  
• Tip tinner / cleaner(Fig: 9 above): This will easily remove the burnt on resin that your sponge will not remove. Use it sparingly though as it is acidic and will dissolve your tip over multiple uses.
  
• Solder(Fig: 11 and 12 above): Having several sizes of solder is nice and will make your life much easier. I also keep 2 different kinds of solder on hand. Regular tin / lead solder, and lead free solder. Lead free solder seems to bond better to silver wires found in Cat5 and Cat6 cables as well as many wires found in PSUs.

Cleaning and tinning the soldering tip.

The first thing we need to cover is how to clean your soldering irons tip. You will never make a good solder joint with a dirty tip. The reason being is that the carbon buildup on the tip from burnt flux acts as an insulator preventing the heat from transferring from the tip to the work piece. 90% of the time the tip can be cleaned by wiping the hot iron on a damp sponge or paper towel. The sponge should be just wet but not enough to drip. Wipe your tip across the sponge in one smooth motion, then rotate the soldering iron and repeat until you see bright silver metal instead of black. You may have to do this several times before the iron becomes clean.

If the wet sponge method does not clean the iron tip then more drastic and risky cleaning methods are needed. Some times the burnt flux gets baked on to the point where it needs to be removed by force and chemical means. This is where the tip cleaner / tinner I spoke of earlier comes into play. A quick warning though. A quick warning though, as the tip cleaner / tinner contains a very strong flux and solder mixture and is quite acidic. Using this on your soldering iron tip will reduce its life span as the acid will remove a little bit of the tip. Don't worry though as you should have an iron with a replaceable tip and replacement tips are cheap. Before we use the tip tinner / cleaner we need to first prep the tip.

To do this take a fresh razor blade and, with the iron cool, use the blade to remove any thick chunks of carbon. Once I have the bulk of the carbon removed I use a piece of 1500 grit sand paper to remove the rest of the carbon. I like to lubricate the sandpaper with water to keep the tip nice and smooth. You are not trying to polish the tip to a shine, just remove 90% of the black carbon build up. Once you get to this step use a wet paper towel to clean off any residue left from the sand paper then turn your iron on. If you have an adjustable temperature iron it should be set hot enough to melt normal solder.

Once the Iron is up to temp carefully place it on to the surface of the tip cleaner. It should melt the cleaner and you will see smoke. Roll the tip around in the molten cleaner and then pull the tip out and wipe the little solder balls off on your wet sponge. Repeat the process several more times until your tip is nice and silver. Once again wipe the tip on the wet sponge and remove any solder ball buildup. We now need to protect the clean tip from any oxidation that may occur. To do this we will coat the tip in fresh solder from our roll. This is called "tinning the tip", or ToT. This extra coating is a best practice to ensure the tip is properly tinned). To tin the tip we simply take some solder from our roll and apply it directly to the tip until the tip is covered in solder. Do not let the solder blob up because all it takes is a thin coating to protect the tip. ToT is something you should do every time you finish soldering a project. If you turn the iron off for what ever reason, you should ToT first. If you do this every time the soldering tip will last a very long time.

Connecting two wires with solder.

This is the basic use for solder. Its something that every modder will have to do at some point. It's not hard to do, but most chose to just use a crimp connector. Crimp connectors make for a crude, unreliable, and noisy connection. This is because the wires are just being held together from pressure. The noise comes from the tiny microscopic sparks that are made from the gaps between the wires in the connection. Soldering eliminates this by filling those gaps with metal. The bond between solder and the wires is a very solid and reliable connection that is less likely to fail.

Before we can solder 2 wires together we first need to strip the insulation from the wire ends. You can use a wire stripper, a knife, or what ever you like. I like to use a razor blade. It's quick, takes up less space on my work bench and very precise. I do recommend using a purpose built wire stripper though as its fool proof and quick. For wire to wire connections all you need to strip is 1/4" away from the ends. This is plenty of wire surface for a strong connection and will use less heat shrink. 1/4" is also good because once we apply the heat to the wires, the insulation will shrink back another 1/16" or so.

I like to use a fresh razor blade to strip wire.

Lets talk about the right way and the wrong way to connect 2 wires with solder. I see lots of people twisting the wires together then trying to solder them with little success. This is because twisting the wires together leaves little to no room for the solder to flow between the wires. Molten solder flowing between the strands of wires is necessary to get a proper and strong joint. I like to just mesh the wires together by holding the wire end to end and meshing them together. This leaves ample room for the molten solder to flow between the wires and keeps the wires nice and straight. If the wires do not have an open end remember to place your heat shrink on one side before you solder them together. If you forget then you will have to use ugly electrical tape.

Fig 1: Proper mesh of 2 wires

Lets get onto soldering the wires together. Place the wires you just meshed together into the clips of the helping hands. Apply some solder to your tip. You want a small blob to form on the surface of the tip. This blob of solder acts as a thermal interface material to transfer heat from the tip to the wires, much like Artic Silver does between your CPU and heat sink. to transfer heat from the tip to the wires. Now place the tip on the bottom of the wires making sure the blob of solder makes contact with the wire. You can add a little more solder here if you need to. Now apply solder to the top of the wire. In just a second you should see the solder begin to melt and flow between the wires. Continue adding solder until the joint is full of solder like the image below. If it looks fully saturated with solder, you can remove the solder and iron. Let the joint cool and then you can move on to heat shrinking.

Fig 1: Heat the wire from the bottom and apply the solder to the top. This will allow the solder to flow through the wire strands.

Heat the wires from the bottom and apply the solder to the top. This will allow the solder to flow through the wires.

Fig 1: A proper solder splice

The finished joint should look something like this.

Fig 1: Heat shrink on wire.

Remember to place your heat shrink on the wire before hand.

Fig 1: With torch on low and about 2 inches from the wire, shrink the heat shrink.

Using a heat source (match, lighter, mini torch, heat gun, etc) heat the heat shrink tubing evenly on all sides until it has fully shrank.

This concludes part 1 of our soldering tutorial. Check back next month for part 2 where we will cover soldering LEDs and resistors together.