How to Solder


During small talks with the audience, one of the key reasons they are not willing to take up electronics because of the soldering of components and wires. To them, it is something new, looks complicated and, dangerous.

There is some truth in what was being said but here are some observations:
1. Soldering is not difficult. It’s something new and naturally, your mind is trying to stop you from doing it.
2. Soldering is a technique of transferring heat from the soldering iron to the solder and the component.
3. In soldering, speed is critical so things do not get cooked.
4. Solder flux is the Magic which makes everything go together.
5. Hotter irons is not necessarily better. It helps to burn things quicker.
6. Soldering is an acquired skill. Just because I was an Engineer does not mean I knew how to solder like a Boss right off the Uni.


Metal will corrode or rust and quicker if it was subjected to heat. The soldering iron is no different. After awhile, the tip becomes hot and starts to oxidise. This burns the flux which creates a film or barrier on the tip. It becomes difficult to melt solder and coat the soldering iron tip. So, every now and then, I would wipe the soldering tip on the damp sponge. If that does not work, I will dip the tip into the flux, then melt a short length of solder around it. This will tin the tip and also to stop the acidic flux from eating into the tip’s protective coating. This works for me because my solder is not lead-free.


I use 60/40 rosin cored solder. And as I solder, the melting solder will give off fumes. The fumes are not from the metal but from the burning rosin flux and few other acids inside the solder core. So, you will need to be working in a well ventilated area. If you’re not wearing glasses, do invest in a pair of safety glasses to prevent hot solder or rosin splatter. You might even need to use those 3M face masks or a fume extractors to minimise breathing in the fumes. In my case, I am using a fan to blow from across from where I am sitting and onto the open windows.

Whatever you do, please take a break after a few minutes and also, wash both your hands and face.

Gary Davies explains how toxic the solder fumes are


Hah. I could not make any proper videos so you can find lots of these on the Internet or on YouTube. Here are some which is very good:

Soldering Crash Course: Basic Techniques, Tips and Advice! by wermy
I like his explanation as his ideas are almost identical to mine and also, he is using almost the same type of 7-core wires I am using for model kits. Towards the end, I did learn a few more things like hot-air gun with a smaller and narrower nozzle does exist, a silicon soldering pad and so on.
Go to his Website for more exciting stuff:


My circuit boards now uses as much SMD components as I possibly can. Scale model kits have limited space inside and so, I have to design my circuit board as compact as possible. The only difference is that I hand-solder all the boards at the moment. SMD components are smaller and uses less power than their bigger though-hole counterparts. They also sit on the surface of the PCB.

So, I have to re-think on how to populate both sides of the PCB and, upgrade my soldering tools in the process.

This video by Orbiter Electronics shows how soldering SMD chips are done although he is testing two versions of the solder flux. If you are interested, you can start form the beginning of the video.

In most cases where I am not soldering SMD to the PCB, I would be soldering wires to tiny SMD LEDs. This is where I would either use a pair of reverse tweezers or a 3M grey double-sided tape. To me, the 3M tape lasts slightly longer during soldering.

The pair reverse of reverse tweezers are holding the 0402 (not 0403) SMD LED which measures 1.0mm x 0.5mm. Although it looked difficult, as long as you tin their solder pads, you can solder wires to them.

Anyway, here is the video below, of me trying to solder 0805 SMDs. They are small but is actually quite easy. I am using a 3M double-sided grey tape to hold the LED. This tape is good as it can stand the heat a few more seconds before it fails. But for me, this is not an issue.

I really, really hate my own voice


Recently, more and more modelers are using solder to join photo-etched brass parts. Before that, it was Superglue and epoxy. There are a lot more steps before you can solder, which usually lies in the preparation stage:

Cut out the part
Prepare the surface to be soldered
Bend and pose the part
Add liquid flux

And with brass, you cannot heat it for too long as it could burn the pre-painted surface. You could also end up annealing the metal itself. Lastly, you will need to learn to control the flow of the solder or it might pool up to a certain area.

A very important tip with Xyla Foxlin about soldering and welding at 4:24. It is a word of difference and after some years, the lead content would fail, I guess.