UPSC Prelims 2006 Q128: Science & Technology – Materials & Engineering
Which are the materials generally employed as solder in soldering operation in electronics?
- (a) Iron and tin
- (b) Lead and tin
- (c) Aluminum and lead
- (d) Aluminum and iron
Answer: (b) Lead and tin
Explanation
Solder used in electronics
| Combination | Used as solder? |
|---|---|
| Iron and tin | No, iron melts at too high a temperature |
| Lead and tin | Yes — the alloy melts at a low temperature and joins components |
| Aluminium and lead | No |
| Aluminium and iron | No |
Solder is a low-melting alloy, generally of lead and tin, used to join electronic components.
Answer: (b) Lead and tin.
Why each option is right or wrong
- (a) Incorrect. Iron has a very high melting point, so iron and tin is not solder.
- (b) CORRECT. Solder is generally an alloy of lead and tin.
- (c) Incorrect. Aluminium and lead is not a standard electronics solder.
- (d) Incorrect. Aluminium and iron have high melting points and are not solder.
Key point
Electronic solder is generally a low-melting alloy of lead and tin.
Remember
Solder in electronics is generally lead and tin.
Common mistakes
- Choosing a combination with iron, which melts at a high temperature.
- Forgetting that solder must melt below the component damage temperature.
- Confusing solder with brazing alloys.
Exam tip
Solder = tin-lead (about 60:40) in classic electronics; lead-free versions use tin-silver-copper.
Sources
- Encyclopaedia Britannica — solder
- ASM International — ASM Handbook, Volume 6: Welding, Brazing, and Soldering