How to Solder Wire to PCB
You attach wires to printed circuit boards (PCB) in a process called soldering. You heat the wire and PCB pad, melting the solder wire and allowing it to flow onto the wire and pad. The solder wire used is typically a lead-tin alloy although in some special cases, silver is used. Soldering a wire to a printed circuit board may be part of making, repairing or modifying the board or connecting it to another device.
Clean the pad on the circuit board where the wire will be attached. Gently rub the eraser on the pad until it is clean and shiny. Strip about 1/4 inch of insulation from the wire.
Tin the end of the soldering iron by melting a small amount of solder onto the iron tip. Heat the wire end with the soldering iron for a few seconds and briefly touch the solder wire to the bare wire, just long enough to melt the solder, and let it flow into the stranded wires. This is called tinning the wire. Tinning the wire is not necessary with solid or single strand wire.
Insert the wire end through the hole in the circuit board pad from the top or component side of the board. Bend the end of the wire slightly to prevent the wire from falling out while soldering but do not let the wire end touch any other component lead or another pad on the circuit board.
Apply the soldering iron tip to the wire end and solder pad at the same for a few seconds until the solder used to tin the wire end melts. Apply just enough new solder to make a dome-shaped puddle on the pad that covers the hole and the wire. Remove the iron from the pad but do not move the board for a minute.
Cool the new soldered joint and do not move the board until the solder hardens. Clip the wire end off with the wire cutters. The wire is permanently attached to the printed circuit board.
- Heat the wire and the pad with the soldering iron, not the solder. If the solder is heated with the iron, it will melt but won't bond electrically to the pad or the wire.
- Do not overheat the circuit board pad because the trace it is connected to will pull away from the circuit board.
- Wash your hands when you are done soldering. The lead in the solder is poisonous.
Michael Logan is a writer, editor and web page designer. His professional background includes electrical, computer and test engineering, real estate investment, network engineering and management, programming and remodeling company owner. Logan has been writing professionally since he was first published in "Test & Measurement World" in 1989.
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