Desoldering and Fixing Bad Joints

Undoing mistakes without damaging the board.

A solder sucker pulls molten solder away, and desoldering braid wicks it up. Heat the joint, remove the solder, and wiggle the lead free. Add a little fresh solder first if the old joint is stubborn, because it helps heat flow.

Common faults are cold joints, which look dull and grainy, and solder bridges between neighbouring pads. Reheat a cold joint with a bit of fresh flux and solder. Remove a bridge by drawing a clean, hot tip or braid between the pads.

• Do not overheat pads; they can lift off the board.
• Clean flux residue afterward.
• Practise on scrap boards first.

Browse all 50 physics and electronics pages  |  Back to the course index