What is the percentage of tin in soft solder?

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ALP CBT 2 Fitter Previous Paper: Held on 21 Jan 2019 Shift 1
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  1. 30%
  2. 63%
  3. 42%
  4. 50%

Answer (Detailed Solution Below)

Option 4 : 50%
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Explanation:

Soft Solder

  • Soldering is the process by which metallic materials are joined with the help of another liquified metal (solder)
  • Soldering can be classed as soft soldering and hard soldering.
  • The process of joining metals using tin-lead solders which melt below 420°C is known as soft soldering
  • The process of joining metals using hard solders consisting of copper, zinc, cadmium, and silver which melt above 600° is known as hard soldering
  • The soldering metal produced by alloying tin and lead is called soft solder which is widely used in an industrial and domestic applications.
  • The solder is designated by two numbers, such as 60/40.
  • The first number refers to the percentage of tin and the second number refers to the percentage of lead.
  • The 60/40 number indicates 60% tin and 40% lead and is the most used best composition having a low melting point of around 190°C and giving sound results while soldering electrical components.
  • Some other most used soft solder compositions are 70/30 and 50/50 although soft solders are available with tin and lead percentages varying between 10% to 90% depending upon their utility.
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