What You'll Need

I've wanted to make this video for a long time. Most of the projects I show involve some amount of soldering, and I always try to give tips for whatever specific type of soldering I'm doing. But I still see comments from people saying they'd love to try these projects but the soldering is what's holding them back.

So this is for those people. Soldering isn't as scary or as hard to learn as you might think.

I'll start with some basic concepts and common mistakes, then show techniques for different types of components, and finish with advice on what to look for when buying a soldering iron and other tools I recommend.

  • Soldering iron (adjustable temperature recommended)
  • 60/40 rosin core solder (tin/lead, preferably thin diameter)
  • Wire strippers
  • Heat shrink tubing
  • Multimeter
  • Helping hands (quad hands or similar)
  • Wire tip cleaner
  • Tip tinner and cleaner
  • Silicone soldering pad
  • Isopropyl alcohol (for cleaning flux residue)

Basic Concepts

Soldering is fusing two electrical components together using a metal alloy called solder. (Yes, I know most other countries pronounce the "l" in solder. We don't in the US — wasn't my idea.)

The solder I like is 60/40 rosin core — 60% tin, 40% lead. You can get lead-free, but I find it harder to work with. If you use leaded solder, just wash your hands when you're done.

Rosin core means the center contains flux. Flux cleans metal surfaces and removes oxidation so the solder can actually fuse with them. Some flux is thin and evaporates as you work. Thicker flux leaves a sticky residue that can be corrosive — clean that off with alcohol.

If you're using rosin core solder, you usually don't need extra flux for basic work. But flux is useful for ribbon cables or tiny PCB pads because it creates better surface tension to pull the solder where you want it.

Common Mistakes Beginners Make

Mistake #1: Melting solder onto the parts like icing on a cake. That's not how it works. You need to heat up both things you're trying to join together, then melt the solder into them. If you just dribble solder on, you'll get a cold solder joint — it looks connected but hasn't actually fused. You'll get an intermittent connection at best, no connection at worst.

Mistake #2: Using too much solder. Less is more. Only use enough to make the connection. Sometimes you need a bit more for physical reinforcement (like on the Minty Pie where the button board connects to the power board), but most of the time, just enough is plenty. Too much solder and you'll bridge neighboring components, which can be really bad.

A good starting temperature is 300-325°C.

Step-by-Step Techniques

Through-Hole Components

These are components with long legs that go through a circuit board — resistors, capacitors, LEDs. You find them on commercially made boards too.

  1. Insert the component into the pinholes
  2. Bend the legs outward to hold it in place
  3. Use the tip of your iron to heat both the pinhole and the leg at the same time
  4. Feed a little solder onto it

That's it. Hardly any solder needed.

Header Pins

For attaching header pins to a board (like a tiny Arduino from Adafruit), the easiest way is:

  1. Put the header pins into a breadboard to keep them lined up and perpendicular
  2. Heat both the pinhole and the pin
  3. Feed a little more solder than usual — these take some stress when you insert and remove from breadboards

Do one on each side first, then go down the line. When you're done, the solder should extend just above the board in a cone shape.

Tinning Wires

Tinning means adding a little solder to wire to make it easier to connect to other components.

  1. Strip a couple millimeters of wire
  2. Twist the strands together tight
  3. Heat them up and apply just a little solder to coat them

You'll do this a lot, so practice it.

Splicing Wires

  1. Strip about 5mm from both wires
  2. Twist the strands together (no solder yet)
  3. Slide a piece of heat shrink tubing over one wire first
  4. Twist both halves together tight
  5. Heat the wires and apply solder — just enough to coat them
  6. Trim if needed, fold the exposed wire parallel to the wires
  7. Slide the heat shrink over it and heat it up

Connecting Wires to Pinholes

  1. Prep the pinhole by heating it from one side and feeding solder down into it
  2. Twist and tin the wire
  3. Heat the pinhole and slide the wire in from the other side
  4. If you didn't use enough solder, add a little to the back

The hole should be completely filled but not sticking out much. Insert the wire all the way through so no metal is exposed on top — that prevents accidental shorts.

Attaching Wires to Pads (No Pinholes)

  1. Strip, twist, and tin the wire
  2. Heat the pad and feed solder onto it at the tip of the iron
  3. You should get smooth bumps sticking up about a millimeter
  4. Heat those blobs and insert the tinned wire

Only strip as much wire as you need. It keeps things clean and prevents accidental shorts.

Fusing Boards Together (Castle Soldering)

This is for connecting boards where pads on one board correspond with pinholes on another (like a Raspberry Pi Zero to a custom PCB). You melt solder down into the pinholes and onto the pads behind them.

This is more challenging. The common mistake is trying to drizzle solder down into the holes — that makes a mess. Instead:

  1. Use a finer tip that can reach into the hole, but not too thin — you need enough mass to transfer heat
  2. Put some solder down into the pinhole
  3. Insert the iron tip behind it for a few seconds
  4. Remove quickly — if you did it right, the solder settles down into the hole

Use a multimeter to check continuity between what you soldered and wherever that pad leads. If you didn't get a good connection, take a piece of wire, heat it up, stick it into the pinhole, and wiggle it around to help the solder make its way down.

Don't use too much solder — it can leak onto neighboring pads underneath.

This article is based on content from YouTube. View original source →

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