Soldering basics
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| Guide details | |
|---|---|
| Topic | Skill |
| Applies to | Both |
| Difficulty | Easy |
| How often | — |
| Tools needed | Temperature-controlled soldering iron Solder Flux Brass tip cleaner Safety glasses Fume fan |
Soldering joins wires and parts with melted metal (solder). It's the key skill for most board and wiring repairs.
What you need
- A temperature-controlled soldering iron. Cheap uncontrolled irons make soldering much harder.
- Solder: for older arcade and pinball boards, leaded rosin-core solder (63/37 or 60/40) is easiest to work with. Lead-free solder works too but needs more heat.
- Flux helps solder flow and makes better joints.
- A brass tip cleaner or damp sponge.
- Safety glasses and good ventilation. A small fan to move fumes away from your face helps.
Temperature
Around 330–370 °C (625–700 °F) works for leaded solder. Lead-free usually needs a bit hotter. Too cold makes dull, lumpy joints. Too hot can lift pads off the board.
How to make a good joint
- Tin the tip: melt a little solder onto the clean, hot tip so it's shiny.
- Heat both parts at once: touch the tip to the board pad and the wire or part lead.
- After a second or two, feed solder into the joint, not onto the iron tip.
- Use just enough solder to flow around the lead and cover the pad.
- Remove the solder, then the iron. Don't move the part until it cools.
A good joint is smooth and shiny and shaped like a small volcano or cone. A bad (cold) joint looks dull, grainy, or balled up.
Reflowing cracked joints
A very common arcade and pinball repair. Heat and vibration crack solder joints over time, especially on connector pins and large parts. Look for thin rings around the pins. To fix: add a little flux, heat the joint, and add a small amount of fresh solder.
Safety
- The iron is hot enough to burn instantly. Always return it to its stand.
- Wash your hands after using leaded solder, and don't eat while soldering.
- Work on unplugged, discharged equipment only. See Before you open a machine.