ARRL Technician Practice Exam

Which of the following types of solder is best for radio and electronic use?

1. Lead-free solder

2. Flux solder

3. Rosin-core solder

4. Acid-core solder

The correct answer is: Rosin-core solder

Rosin-core solder is considered the best choice for radio and electronic work due to its formulation and characteristics that are particularly suited for delicate electronic components. This type of solder contains a core of rosin flux, which helps to clean the metal surfaces being soldered as the solder melts. This cleaning action is crucial for achieving a reliable electrical connection and minimizing oxidation. The rosin flux is non-corrosive and is effective in preventing future corrosion, which is a significant advantage in maintaining the integrity of electronic circuits. Additionally, rosin-core solder provides good wetting and adhesion properties, allowing for strong joints that are essential for the longevity and functionality of electronic devices. In contrast, lead-free solder can have a higher melting point and may not flow as smoothly as rosin-core options, making it less favorable for intricate soldering tasks. Flux solder generally refers to a product without a specific core, which might not ensure the same level of effectiveness as rosin-core solder. Acid-core solder is primarily used in plumbing and metalwork; its acid flux can damage electronic components by leaving corrosive residues, making it unsuitable for radio and electronic applications.