Editors Note: Always wear the proper eye protection when soldering.

As you become more involved with rc airplanes, its likely that you’ll need to solder some type of electrical or mechanical component at some time. This skill becomes even more important as you progress further into the world of electric rc airplanes.

Selecting your equipment

Here’s what we recommend:

  • 45-60 watt soldering iron
  • Soldering stand with clips
  • 63-37 [or] 60-40 solder (tin-to-lead ratio)
  • Desoldering braid (to clean up excess solder)
  • Rosin flux (This is optional when using Rosin Core solder)
  • Small damp sponge
  • X-acto knife
  • Wire cutters

Most all soldering for rc should be done with a soldering iron, not a soldering gun, as a soldering iron allows for more precision through the design of a pencil or modified chisel shaped tip. A soldering gun, however, has a larger shaped tip and is generally used in heavier applications such as soldering brackets or metal plates.

An alternative to a soldering iron is a soldering station. A soldering station has its own power supply, allowing you to adjust and keep the temperature of the iron constant. This differs from a standard iron that can loose temperature when you apply heat to a joint and can increase in temperature when idle. And while having the precision of a soldering station is desirable, the cost of a soldering station can be significant and for most hobby applications a simple soldering iron will suffice.

Soldering should be done with a soldering iron rated at approximately 45-60 watts and have a tip size of around 1/4″ or 5mm. Your choice of solder should be 63-37 or 60-40 rosin-core (NOT acid-core), which is the most commonly used solder for rc. This tin-to-lead ratio provides rapid solid to liquid transitions and has the best stress resistance.

Preparing to solder

Always do your soldering on a flat, even surface that is fire resistant as you may drip solder at some point in time. Also, before turning on your soldering iron, check the tip and see if it is clean of residue. If not, wipe or lightly sand the iron’s tip, removing any build-up of rust or corrosion or if necessary, replace the tip.

Once your iron is at temperature, and before you begin soldering, the tip must be tinned. “Tinning” is the process of coating a soldering tip with a thin layer of solder. This aids in heat transfer between the tip and the component you are soldering and gives the solder a base from which to flow.

During the process of tinning and of soldering, frequently wipe the soldering iron’s tip off on the wet sponge to remove all flux residue. A clean and tinned soldering iron tip ensures good conduction of heat. Additionally, when you store the iron in the stand for a long period of time without use, ‘re-tin’ the tip to help the iron dissipate excess heat when not in use. This will save wear and tear on the heating element and extend the life of your soldering iron.

Soldering basics

The following is a step-by-step approach to some common soldering techniques that you’ll run across frequently when soldering for radio control & model airplanes.

Soldering wire to a surface

  1. Cut & tightly twist the wire. We like to add a drop of rosin flux as it helps increase the efficiency of molten solder flow (i.e. Creates a solid electrical connection).
  2. Tin the wire by heating the wire with the soldering iron and touching the solder to the wire and not the iron’s tip.
  3. Clean & prepare the surface that wire will be soldered on to. When necessary, use desoldering braid to remove excess solder from a surface.
  4. Melt a small drop of solder on to the surface where the wire will be connected.
  5. Place the wire on the surface & apply iron’s tip to the wire, not to the surface (Note: Shiny solder is good, dull solder indicates a ‘cold connection’ which is weak).

Splicing Wire: Method 1

  1. Cut wire A’s (red) silicone covering to expose approximately 1/4 inch of wire.
  2. Tin Wire A’s exposed surface. We like to add a drop of rosin flux as it helps increase the efficiency of molten solder flow (i.e. Creates a solid electrical connection).
  3. Cut & expose Wire B and flux & tin.
  4. Solder the joint using soldering stand clips (if available).
  5. Insulate the connection using heat shrink tubing.

Splicing Wire: Method 2

  1. Cut Wire A’s (red) silicone covering to expose approximately 1/4 inch of wire.
  2. Rosin flux & tin Wire A’s exposed surface.
  3. Cut approximately 3/4 of an inch of Wire B’s (black) covering.
  4. Divide wire B’s strands into 2 equal twisted portions.
  5. Rosin flux & tin Wire B’s strands.
  6. Wrap Wire B around Wire A (A needle nose pliers will help).
  7. Solder the joint using soldering stand clips (if available).
  8. Insulate the connection using heat shrink tubing.

Remember to:

  • Clean and tin your soldering iron tip frequently
  • Tin the parts of the wire that are to be joined
  • If possible, twist the wires together before soldering for a good connection
  • Don’t over tin wires or apply too much solder to the connection

2 Comments

  1. Felipe hernandez
    February 12, 2016

    Great work on soldering, wire connections and nice vivid pictures too!!

  2. Chatter
    February 13, 2016

    Thanks! I appreciate the feedback.

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