Learning to solder

My daughter and I have been planning and building a robot that goes around the house, recognizes people and speaks. For this I’ll need to solder some microphones, a DAC and probably a speaker too.

Usually I would go with preassembled parts that we just need to fit together with some screws and that’s it.

The two main reasons for going with soldering are:

1. Cheaper hardware. If you’re putting in the work yourself, you’re not paying someone else to do it for you.

2. More options and an open ecosystem. I can pick a board or flash custom firmware without getting locked into an ecosystem.

   I had this experience with mBot 2, a STEM robot with all sorts of content for kids to learn. While it is a good experience, once you want to do something that deviates from what they allow, you have to buy their options or you’re stranded.

This is a terrible idea

For me, that is. Having really limited close up vision on my only working eye is kind of a huge red flag. I went with a basic magnifier yet it is not enough for me. Latency on the phone magnifier means that I may need to invest in a sort of digital microscope.

My fine motor skills are far from decent. I remember in school the activities that required these skills always seemed out of reach for me. Let alone going 30 years without practicing them.

What I got

• Soldering iron kit

  I went with an iron kit instead of a station on the advice of Dr. Tiago Pimenta. He’s been doing this for years and unsuccessfully trying to convince me to join in. It is cheap and already includes a few essentials:

  • 5 soldering tips
  • Desoldering pump
  • 50 g solder wire
  • Wire stripper
  • Useless stand (not enough weight to hold the iron)
  • Tiniest of sponges
  • Tweezers
  • Case for the kit

• Flux

  Essential! Don’t skip this.

What I didn’t get

• Solder wick. Apparently you can get by with just a stranded copper wire. It is useful to absorb solder after a bad job. And I’ll be doing a lot of bad jobs.
• Leaded solder wire. Much easier for beginners since it has a fixed melting point unlike lead free. Probably should’ve gotten this.
• Brass solder tip cleaner. Very useful to make your tips last much longer and make it easier to prepare the tip for soldering.
• Third hand soldering holder. Very useful to keep things steady. It can hold PCBs, wires and even the solder wire for you. When I was looking for magnifiers I saw some with this included.

As with everything I should’ve learnt a bit more about this before shopping. But I can’t stand learning something and not being able to put my hands in the dirt. And here we are.

The good part is that none of the missing parts are really that expensive. But I can already see that this is a rabbit hole that you can sink loads of money into!

Actually learning

I’ve started with a few YouTube videos (as one does to consider themselves an expert in an hour):

iFixit’s soldering 101

How to solder (beginner’s guide)

Soldering crash course: basic techniques, tips and advice

Do this before you solder anything

First learnings

1. Heat up what you’re going to solder instead of heating the solder with the iron. This allows the solder to evenly spread and make good contact with the surfaces you’re trying to solder.
2. Always clean up the tip after using it.
3. Precondition the tip with a bit of solder and clean up before soldering.
4. Use a bit of flux, especially on pads. It will make your life much easier.
5. To attach a wire to a pad put a bit of solder first on the pad then the wire and a bit more of solder after.
6. Bend pins when soldering upside down. It holds the component to the board while you solder and then you may cut the excess of the pin.
7. Temps: around 320ºC for leaded solder and 350 to 370ºC for lead-free solder.
8. Ensure good ventilation even if you’re using lead-free solder.
9. Clean up excess flux with Isopropyl alcohol 91% or higher to avoid corrosion.

Time to try it myself

One thing I forgot was to get a practice board, I guess I’ll find broken stuff at home and make them even more broken! Wish me luck!