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Learning to solder: tools, technique and safety

Properties1
tagsglossar, elektronik, werkzeug

2 min read

Learning to solder: tools, technique and safety

In short: When soldering, molten solder joins components electrically and mechanically; with a temperature-controlled station, flux, a clean tip and ventilation you get reliable joints.

In more detail: Soldering is a basic skill for tinkerers: repairing cables, kits, Arduino projects, retro repairs (controllers, batteries, capacitors). Practise on perfboards and scrap.

In Depth

Tools

  • Soldering station with temperature control (about 280 to 350 °C lead-free, 250 to 320 °C leaded), fine chisel/pencil tip.
  • Solder 0.5 to 1 mm: lead-free (SAC305) or leaded (Sn63/Pb37) (not for food/children’s toys; RoHS rules apply to electronics sold in the EU); with flux core.
  • Flux gel/pen, desoldering braid and desoldering pump, sponge/brass wool, third hand, tweezers, side cutters, wire stripper, heat-shrink tubing (+ hot air), isopropanol (cleaning).
  • Good magnifier/light; solder fume extraction.

Technique

  1. Tin the tip (a little solder), keep it clean.
  2. Fix components, leads clean/bright.
  3. Heat pad and lead simultaneously (1 to 2 s), then feed solder to the joint (not to the tip), let it flow 1 to 2 s.
  4. Remove the tip, do not move until it solidifies (shiny, concave “volcano” shape).
  5. Check: cold joint (dull, ball-shaped, cracked) → resolder with a little fresh solder/flux.
  6. SMD: flux, little solder, tweezers, possibly hot air/solder paste.
  7. Desoldering: braid with flux, or pump; do not overheat the board (pads lift).

Safety

  • The tip is > 300 °C: burn risk, use a stand/holder, never leave switched on unattended.
  • Do not inhale solder fumes (flux): ventilate/extract.
  • Lead: wash hands, no eating/drinking while soldering; dispose of waste as hazardous waste/recycling centre.
  • Splashes in the eye: safety glasses when cutting/desoldering.
  • No soldering on live devices; mains devices, CRT TVs only with expertise. Do not solder batteries (Li-ion/LiPo) directly (heat → fire), use spot welding/prepared solder tabs.
  • Anti-static for sensitive ICs.
  • Teenagers: learn under supervision, keep fire protection in mind.

Practice and projects

  • Solder kits (blinker, radio), perfboard, solder headers to Pi Pico/Arduino.
  • Retro repair: replace electrolytic capacitors (polarity!), buttons, controller cables, battery replacement (back up saves: save batteries in game cartridges).
  • Joining cables: tin the stranded wire, slide heat-shrink on first.
  • Fault finding with multimeter, magnifier, take photos beforehand.
  • Documentation, schematics, forums and videos (repair communities).
  • If unsure: ask a repair café/makerspace.

See also: Using a multimeter, Electronics basics, Arduino and microcontrollers, Using lithium-ion batteries properly

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