The art and science of soldering is one that takes a lot of practice. While over time one can perfect their soldering technique, this blog provides a basic introduction to soldering. There are four major factors that affect the quality of a soldered joint—cleanliness, temperature, time, and adequate solder coverage. Each of these factors is discussed below.

Cleanliness: All parts, including the iron tip itself, must be completely free of grease, oxidation, and any other type of contamination. Any sort of contamination makes soldering extremely difficult. In the case of oxidation, you can use a hand-held file, a knife blade, or an emery cloth to reveal the fresh metal underneath. For other types of contamination you can use a fiber-glass filament brush.

Temperature: The temperature of all parts should be raised to the same level before applying the solder. The melting point of most solder is 188 degrees Centigrade (370 degrees Fahrenheit). The iron tip temperature is usually 330-350 degrees Centigrade (626-662 degrees Fahrenheit). Keep in mind that lead-free solders require a higher temperature.

Time: Too much time will damage the component, and perhaps even the circuit board copper foil. Heat the joint with the tip of the iron, then continue heating while applying the solder. Then remove the iron to allow the joint to cool. With practice, this should take a few seconds. Larger parts typically require more heating than smaller parts, but some parts—such as semiconductor diodes and transistors—are sensitive to heat and should not be heated for more than a few seconds.

Solder Coverage: Too much solder is wasteful and may cause short circuits with adjacent joints. Too little solder, on the other hands, may not support the component properly or may not fully form a working joint. Determining the right amount of solder only comes with practice. Typically only a few millimeters is enough.

If you are interested in learning more about soldering, check out Blackfox’s solder training programs. Appropriate for novice and experienced learners, Blackfox is recognized in the electronics manufacturing industry as a premier technical training center with courses designed for hands-on learning. See the course calendar for schedules.


Winstanley, Daniel. (1996). The Basic Soldering Guide. Everyday Practical Electronics