10 Common Soldering Mistakes (and How to Fix Them)

Every solderer makes these mistakes early on. The good news: each has a clear cause and an easy fix. Practice spotting them on a cheap practice board and they’ll soon disappear.

1. Cold solder joints

The problem: Dull, grainy or blobby joints that crack or fail. The solder never fully melted and flowed.

The fix: Use enough heat, heat the joint (not just the solder), and hold steady while it cools. Reheat bad joints with fresh solder and flux.

2. Heating the solder instead of the joint

The problem: You melt solder onto the iron and dab it on. It won’t bond properly.

The fix: Press the tip to both surfaces first, let them heat, then feed solder into the joint.

3. A dirty or un-tinned tip

The problem: A blackened, dull tip won’t transfer heat, so nothing flows.

The fix: Wipe on brass wool and re-tin with a little solder until shiny. Do this often.

4. Too much solder

The problem: Giant blobs that can hide cold joints or bridge to neighbours.

The fix: A joint needs just enough to form a small cone. Feed less; you can always add more.

5. Solder bridges

The problem: Solder accidentally connects two adjacent pads or pins.

The fix: Add flux and drag a clean tip across the bridge, or wick it away with desoldering braid.

6. Lifted or burned pads

The problem: Too much heat for too long lifts the copper pad off the board.

The fix: Work quickly (2–3 seconds per joint) at the right temperature. If a pad lifts, you may need to repair the trace.

7. Wrong temperature

The problem: Too cold and solder won’t flow; too hot and you damage parts and burn flux instantly.

The fix: Around 315–340°C (600–650°F) for leaded solder; a bit hotter for lead-free. Use the lowest temp that makes a clean joint in a couple of seconds.

8. No flux

The problem: Solder beads up and refuses to wet the surfaces.

The fix: Use rosin-core solder, and add extra flux for tricky or surface-mount joints. Flux cleans the metal so solder can bond.

9. Moving the joint while it cools

The problem: A disturbed joint solidifies fractured and unreliable.

The fix: Hold everything still for a second after you remove the iron. Helping hands make this easy.

10. Skipping safety

The problem: Burns, breathing flux smoke, or eye injuries from spitting solder.

The fix: Ventilate, wear safety glasses, keep the iron in its stand, and never touch the tip. See our beginner guide for a full safety rundown.

When a finished board does not work

Most “dead kit” faults come from the mistakes above. Work through them in this order before assuming a component is faulty:

1. Look first. Under good light or a magnifier, check every joint for dull cold joints, solder bridges and pins that were never soldered at all.
2. Check orientation. LEDs, diodes, electrolytic capacitors and chips only work one way round. Compare each with the silkscreen marking.
3. Check values. A resistor in the wrong position is easy to miss — our resistor color code calculator decodes the bands.
4. Test continuity. With power off, a multimeter confirms each suspect joint connects and neighbouring pins do not.
5. Power up carefully. A current-limited bench power supply shows a short straight away as a high current reading instead of a burnt part.
6. Reflow anything doubtful. A dab of flux and a quick reheat fixes most intermittent faults — see how to fix a cold solder joint.

Mistakes that are easy to make with lead-free solder

• Judging joints by shine. Lead-free joints are naturally satin; check the shape instead.
• Turning the heat up instead of using a bigger tip. More temperature mostly burns flux and wears the tip.
• Skipping flux. Lead-free wets less readily and needs it more.

The lead-free vs leaded guide covers hand-soldering lead-free in detail.

The cure for all of these is repetition on cheap boards where mistakes don’t matter. A multi-pack practice kit or a high-joint-count project like the LED chaser gives you plenty of reps to build clean, confident technique.