Soldering Basics

Adapted from "Getting Started in Electronics" by F. Mims, 1983, Radio Shack 62-5003

Hints and Tips

  1. Use a low-wattage soldering iron (24 to 40 watts). Soldering guns are way to big for electronics work.
  2. Tin the tip of a new iron according to the manufacturer's instructions. (Or, see below.)
  3. Always use 60/40 rosin core solder for electronics components. Diameter 0.031 is recommended.
  4. Solder does not adhere to grease or paint. If in doubt, clean surfaces with a solvent or rub with steel wool. (Usually this will not be necessary.)
  5. Careful of burns; the iron is HOT.
  6. Make yourself a soldering iron stand by bending up a coathanger. Just need something to keep the tip from touching the table. Also, keep a damp sponge nearby for wiping the hot tip clean.
  7. Unplug your iron when not in use.

How To Solder

  1. Heat the connection (NOT the solder) for a few seconds with the hot tip of the iron.
  2. Leave the iron in place and apply a SMALL amount of solder from the opposite side of the connection as the iron.
  3. Allow the solder to flow THROUGH and AROUND the connection (but not to blob) before removing the iron. Don't apply too much solder or move the connection before it cools. Don't leave the iron on the connection too long or else nearby insulation will melt.
  4. Keep the tip of the iron clean and shiny by wiping off debris on a damp sponge.

How To Solder A D-Connector

D-Subminiature connectors with 9 or 25 pins are commonly used for computer serial and parallel ports. Here's how to solder wires to them like a professional.
  1. Strip 1/4 inch of insulation from the wire.
  2. "Tin" the bare wire by heating with an iron for a few seconds and then applying a thin layer of solder.
  3. Snip the wire so only about 1/8 inch of bare wire shows beyond the insulation.
  4. Heat the connector solder cup by applying the iron on the outside of the cup. Fill the cup with solder. Let cool.
  5. Position the wire above the cup. Reheat the cup with the iron. When the solder just melts, jam the wire home. If you have done this step properly, the insulation will be touching the top of the solder cup with no bare wire showing.
  6. When all wires have been soldered, apply the connector hood and tighten against the cable jacket for strain relief so that if the cable is pulled, there will be no stress on the soldered joints.

How To Tin an Iron Tip

Your should always "tin" the tip of a new soldering iron to improve solder flow performance and to increase the life of the tip. Here is how to do it:
  1. Warm up iron to its operating temperature.
  2. Melt solder all over the tip so it is nice and shiny.
  3. Let idle for 2 min.
  4. Wipe tip clean on a damp sponge.


Page maintained by wkdurfee@tc.umn.edu
Last modified: Mon Feb 24 09:18:01 CST 1997