This page is to go over the Do's and Don'ts of soldering. Most of our soldering efforts are found after we start a race, when one of the power leads pops off the motor or battery because of our bad solder joints.
Soldering is an activity that is so important in our hobby that we take it for granted. Most attempts I've seen at soldering are a terrible thing to look at. How many of us have ever really learned to do it right? Most go from the cold joint, to the more solder the better.
Having the right equipment to start with is the first thing to look at. We need to solder capacitors to motor cans, and thick 14 or 12ga. wires to batteries, a 20 watt pencil iron is not going to work. But it will work for those re wires on the inside of receivers and speed controls.
I recommend a nice 80 watt soldering iron with a broad tip for most battery building jobs, and a 45 watt for around the track use on wire soldering on motors and batteries. I would stay away from soldering guns, because they are never ready when you need them, and they do not have the large wide tip with all that stored energy to do the job quickly. Anytime the job takes longer than necessary, you can damage batteries and expensive electronic equipment. The key is to have a hot iron that transfers heat quick and doesn't loose it.
Solder is the next thing you need and remember to use the right kind! I use a 60/40 rosin core solder for electronics and small stuff. I use a medium thickness for battery building. The quickest way to destroy components is to use acid core solder. It is not made for anything we do in the R/C car field that I know of.
Clean connections is the next big key to a happy solder joints. Using sandpaper and sometimes a file to clean a spot on a motor can, and a little flux is probably necessary. The flux should be for electrical use. Remember motor magnets are affected by heat, and so are batteries. So by making sure the connections clean, it keeps the time down on the soldering job. On batteries you need to sand or rough up the end of them. I use a sanding drum on the end of my dremel tool, it works fast and quick.
When you are joining everything together the key is to tin your iron (melt solder on it) to get everything going. Then heat the part and let it melt the soldering. This will also help the heat transfer. Apply the heat to the items you are soldering, then apply the solder. It should melt very easy and flow like a thick liquid, if it doesn't then you don't have everything nice and hot yet. Once the solder has flowed over the joint, remove the solder and then the heat, and don't move anything or it will make the joint weak! I have even been told to only let the joint cool at it's own rate, and not to blow on it.
I always tin the wires first, to minimize the amount of heat on the battery also. Another tip on soldering motors is to always make sure the can is clean and that you clean the can up a little where you want the solder to stick with a file to get through the paint and powder coating. Then it requires a hot iron to do properly, or it is impossible when your soldering those capacitors on to the can.
Well if there anything that I have missed, you will probably know it about two minutes into the race.
