I’d like to expand a bit on the excellent tips offered by Phil Laperriere in the July 2010 edition of the AMA Insider, entitled “Understanding Deans“. As someone who has been involved in electronics since I was a teenager, I get a lot of requests from the members of my own R/C club to help them with the same kinds of soldering issues Phil discussed in his article. The recent boom in the popularity of all-electric planes and helicopters, and the ever-increasing size and capacity of the batteries, motors, and speed controllers they use has made what used to be fairly simple tasks very difficult for a lot of modelers. So here are a couple of my own soldering tips.
1. Use a smaller gauge solder. Solder comes in different sizes, just like wire does, and a small gauge solder will melt more quickly and flow much better than a thicker one. I use .032 gauge solder (available at Radio Shack) for all my electronic soldering tasks. It takes much less heat to melt it, which helps reduce the damage excess heat can do to terminals, connectors, and insulation. And the smaller gauge solder has a greater percentage of flux, compared to a larger diameter solder, which helps it stick better to the joints. You’ll be amazed at how much easier it is to use.
2. Use a bigger soldering iron. A larger soldering iron (measured in Watts) will often make a better joint quicker, and with less damage to the terminals and wire. If your iron is too small, you’ll be forced to leave it against the joint way too long, which will allow the heat to travel up the wire and into other parts, causing damage. The bigger iron will heat the joint quickly, resulting in much better, more electrically reliable joint. For most R/C tasks a 35-40 watt iron is ideal, for larger joints on heavy gauge wire, including connections to large ESCs and battery terminals, a 50 watt or larger is even better.
3. Get yourself a flux pen, also available at Radio Shack, or from any good electronics retailer. They’re made like a magic marker, but contain the same rosin flux that’s in the center of the solder. Coat the wire and terminal to be soldered with flux before you “tin” them, and your solder will adhere and flow much better, making a stronger, more reliable connection. Use only rosin core flux on electronic wires, NEVER acid core!
4. Use the soldering iron to heat the joint, not to melt the solder! This is a big one, and very important. The job of the iron or gun is to heat the wire and/or joint to a temperature hot enough so that it, the joint, can melt the solder. Don’t place the solder against the tip of the iron and try to drip it onto the joint. Place the iron against the joint, let it heat the joint, then let the joint melt your solder. Once you get the joint hot enough, the solder will flow over the wires and connectors, coating everything evenly. This is the only way to prevent a cold solder joint, which can rob you of performance and may even break loose completely. Remember, use the iron to heat the joint, not melt the solder. Let the joint do the melting. It takes practice, but it works.
5. Wear a glove. How many times have you had to turn a hot wire loose before the solder had cooled enough to hold it well? How many times has the heat from the joint traveled up the wire and shrunk your tubing before you were ready? Use a pot-holder type glove, or whatever you have, to protect your hands while soldering. You’ll be able to hold the wires longer and more steady while soldering, and they will help cool the wire more quickly once you’re done, which will save your heat-shrink.
I’d also suggest you invest in one of the small devices that have 2 or 3 alligator clips to hold your wires and terminals, sometimes called a “Helping Hands”. (They often also include a soldering iron holder.) Cover the alligator clips with a piece of fuel tubing to pad them and prevent them from marring your wires. They’re great for holding things steady while you apply the heat and solder. Good Luck!
Falling Water Radio Control Flying Club