Installing an FPV system on an RC aircraft without understanding basic soldering is nearly impossible. The good news is that soldering basics aren’t difficult to understand, and the start-up costs are fairly low.
All you need to get started is a soldering iron and some rosin core solder. A few additional supplies will make the job easier and safer, and I’ll explain how those items may help later in this post.
Types of Solder
Solder in general is a metal alloy that is used to join two metal surfaces together. The solder is designed so that it’s melting point is below that of the two surfaces.
Leaded solders used for electronics usually have a melting point between 360 to 370 °F , or 180 to 190 °C, and melt at a single temperature within that range.
An alloy that melts at a single temperature, as opposed to over a range of temperatures, is considered eutectic.
Using a eutectic solder will provide the best electrical connection. Lead-free solders are not eutectic, and make a less reliable connection.
100/140 W soldering gun.
Be sure to only buy solder specifically designed for electrical work. In the big box stores like Home Depot and Loews, you’ll find plumbing solder right next to electrical solder. The plumbing solder is designed for pipes, and uses a different type of flux that is incompatible with electronics.
Lead-Free or Leaded
In the past solder was made from alloys of lead and tin. As public knowledge of lead poisoning increased, companies developed lead-free solders.
These lead-free solders are not eutectic, and can potentially make for less reliable solder joints.
Flux or Rosin Core
Flux improves the solder connection by chemically cleaning the joint location and preventing oxidation during the soldering process.
You can either buy a container of flux and apply it separately during the soldering process, or use rosin core solder, which contains the flux inside of the solder itself. Most recommend rosin core solder as it’s less messy and eliminates the manual application of flux during soldering.
Make sure not to buy acid flux as it’s intended for plumbing use, and will corrode circuit boards.
A 1 pound spool of 0.050 inch diameter 60/40 (60% tin and 40% lead) rosin core solder will last a long time and can be used with a wide variety of wire gauges.
Soldering fume fan.
Soldering irons are used for small gauge wires and circuit board work.
Soldering guns produce much higher heat, and can melt plastic wire coating and connectors.
I use a 40 W iron, and I don’t recommend buying an iron that produces less than that. You’ll need the extra heat for soldering the larger wires.
Sometimes the wires are just too big, and you’ll need to use an instrument that can produce more heat over a larger area.
I’ve found that using a soldering gun makes soldering connectors onto battery packs and speed controllers much easier. A 30-40 W soldering iron doesn’t produce enough heat to allow solder to flow onto the heavy 12-14 gauge wire.
Soldering Iron Tips
You’ll probably need some extra tips for your soldering iron. If you leave your soldering iron on while you’re positioning the wires or doing a lot of soldering, the tip will tend to oxidize quickly. This problem gets worse for higher wattage soldering instruments.
Just as in marketing video game consoles, the manufactures will make their money on the accessories. These tips are usually a few dollars apiece, and a substantial percentage of the overall cost of a soldering station. But it’s best to have a few spares, as an oxidized tip is useless for soldering.
To prevent the tip from becoming oxidized, try to keep the tip tinned. You can learn more about tinning by watching the helpful video at the end of the article.
If you do find yourself with an oxidized tip, you might try using 200 grit sandpaper to clean off the oxidized metal. Use caution though, as the friction will wear down the tip if you sand too hard or too frequently.
The big box stores such as Home Depot, Lowe’s, etc. usually don’t have a large supply of electrical soldering equipment. You’re probably best off using Amazon to get a good deal on a nice soldering station and associated supplies.
Besides the basic soldering iron/gun and rosin core solder, a few other items will make your soldering more efficient and effective.
‘Third Hand’ device.
Sandpaper / Tip Cleaner
I recommend purchasing a soldering iron tip cleaner. I’ve found that the sponges that sometimes come with cheaper soldering stations don’t do a good job of keeping the tip free of oxidation.
But again, if you want to be cheap, you could also use 200 grit sandpaper to accomplish the same thing.
‘Third Hand’ Device
These inexpensive contraptions are lifesavers for soldering small wires together. If you use inline or pigtail splices on small gauge wire, the mechanical connection will come apart if the wires are not supported well.
Solder Fume Extractor
You have to place this small fume extractor close to the soldering surface otherwise it won’t be of much help. But if used properly, you’ll find that a good deal of the solder fumes go straight into the charcoal filter. A face mask with a charcoal filter works well, too. I use both and am much more comfortable not having to hold my breath while soldering.
Soldering Basics Video
Check out this oldie but goodie soldering video from YouTube: