Soldering is the most critical step in the assembly of an electronic circuit. The most common problem with soldering is the formation of cold solder joints.
Cold solder joint is a problem that occurs when the solder is not completely melted during soldering. The cold solder joint increases the electrical resistance of the solder joint. This can lead to some problems by reducing the reliability of the solder joint.
Cold solder joints can be detected by visual inspection. Using a magnifying glass or camera during visual inspection may facilitate detection. The ideal solder joint has a soft, shiny and concave appearance. A cold solder joint has a frozen, whitish, convex and deformed appearance. It is therefore quite easy to separate a cold solder joint from a correct solder joint.
Another way to detect cold solder joints is to use a multimeter that can measure multiple electrical properties. Because there is an increase in resistance where there is a cold solder joint. The multimeter can be used to detect the increase in electrical resistance and test the continuity of the circuit. If you test the resistance with the help of a multimeter and get a reading above zero, you probably have a cold solder joint.
Some mistakes made during soldering may cause cold soldering problems. Common causes of cold solder joint are as follows.
- Using too low or too high temperature during soldering
- Improper melting or rewetting of solder
- Exposure to vibration as the solder cools
- Dirty solder alloy
- Incompatible component geometry
Cold solder joints are one of the most frustrating things for electrical engineers. Although it is not possible to completely eliminate the cold soldering problem, there are some methods that can be applied to reduce this problem.
In order to prevent the formation of cold solder joints, the temperature recommended by the solder manufacturer should be used, vibration sources that may cause uneven distribution of solder should be removed, and a quality solder paste should be used.
