Solder facts for kids

Various types of solder

Solder is a special metal or alloy that melts at a low temperature. People use it to join other metal pieces together. The process of joining metals with solder is called soldering.

There are two main kinds of solder: soft solder and hard solder. Soft solder melts easily, often with a soldering iron. It is commonly used for electronics and electrical projects. Hard solder needs much higher temperatures to melt, usually with a torch.

Soft Solder: Joining Wires and Parts

Soft solder is what you usually see in electronics. It helps connect tiny wires and parts on circuit boards.

Lead Solder: An Older Type

For a long time, a common soft solder was lead solder. It was made of about 60% tin and 40% lead. This type of solder melts at around 185°C (365°F). Lead solder was popular because it was cheap.

However, lead can be harmful. In the past, lead solder was used in water pipes. This caused lead to get into drinking water, which is not safe. It was also used for food cans. Over time, lead could get into the food, making people sick. Because of these dangers, lead solder is now illegal for water pipes and food containers. It is still sometimes used in certain electronics.

Lead-Free Solder: A Safer Choice

Around 2006, many places like the European Union, China, and California started to ban lead in products that people buy. This meant that lead solder could no longer be used in most electronic devices.

So, lead-free solder became very important. Many lead-free solders are made from a mix of tin, silver, and copper. They melt at a slightly higher temperature, around 217°C (423°F). Sometimes, a metal called indium is added to make the solder even better, but indium is quite expensive.

What is Flux and Why is it Used?

When you heat metal, it can get a thin layer of something called metal oxide on its surface. This oxide layer makes it hard for the solder to stick properly.

That's where Flux comes in! Flux is a special chemical that cleans the metal surface. It reacts with the metal oxide and turns it back into clean metal. This helps the solder connect strongly to the metal. A common type of flux is called rosin. Some solders even have a core of flux inside them, so it's applied automatically as you solder.

Other Uses for Solder

Solder isn't just for electronics. Another type of solder is used to join pieces of glass together, or to connect glass to other materials. These solders usually melt at higher temperatures, around 450-550°C (842-1022°F).

Images for kids

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  A spool of solder, ready to be used.

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  A close-up of a soldered joint, connecting a wire to a circuit board.

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  Using a propane torch to solder copper pipes.