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Soldering is a widely used technique to join different metal items. Its reversibility has made it a reliable technique. There are some specific metals that can be soldered. Meanwhile, some metals cannot be soldered. And there are some most used metals to use for soldering.
One common question about soldering is what metal is used for soldering? The answer is, there are so many options but mostly tin and lead along with some other alloy metals.
For your convenience, the particular metals of soldering have been discussed in this article. Let’s start exploring…
What Is Soldering?
First, let’s start with very basic information for absolute beginners. Soldering is a process in which a soldering metal joins two other pieces of metal. Solder is basically a metal that works as a glue in any electrical connection or mechanical purposes.
The whole process in a nutshell-
- The solder is heated to their melting point.
- It starts melting down on the joining metals or wires.
- Then it cools down and solidifies.
- Thus it creates a strong metal bond.
This is reversible as well. This means desoldering is also possible. Soldering iron is one of the most crucial soldering tools.
Soldering is widely used in electronic components to create conductive bonds between PCB components in PCB design etc.
Which Metals Can Be Soldered?
There are a huge variety of options to choose from when it comes to soldering. You have to research which metals you should use for your particular application.
Brass is what comes to mind first when it comes to types of solders. It is easy, reliable, and less complicated. It is consistently used in soldering. For hobbyist applications, brass works quite alright.
Aluminum is a great option too. It needs special solder and stronger equipment.
Lead-based filler metals were used widely. But due to its hazardous effects on the environment and human health, it is now banned. But lead-based ones truly make the soldering process easy. These solders are still preferred in critical applications. Today there are lead-free options to choose from. Antimony, copper, silver, tin, indium, etc are some of those.
Silver, copper, brass, bronze, and steel are some common types of metals that form strong physical or chemical bonds on their own. And other metals such as cast iron titanium, aluminum, etc require some alloy whose melting point is higher.
Lead or tin are soft solders. They have a low melting point. Hard solders form stronger bonds due to their high melting point. However, lead and tin are difficult to process with metals that oxidize easily.
There are some other solders called wiping solders. They are rather fluid and easily manipulated. Cable wiping solder has a high tin content. It provides a strong bond.
Copper, silver, gold can easily be soldered. Iron, nickel, and mild steel are more difficult. And stainless steel, aluminum is tough to solder.
What are the most common metals that are used in soldering?
The two most commonly used metals in solders are lead and tin. Lead was one of the most common solders and widely used. It’s less prone to failure as well. 60/40 is a common ratio to mix lead and tin together to achieve a melting point of 180°C-190°C. It is often called soft solder. Higher tin concentration results in better tensile and shear strength.
The EU banned using lead-based soldering due to its adverse effects. Lead-free solders have a higher melting point in comparison to another conventional solder. Silver solders are a great replacement for lead-based solders. Using nickel as additives can mitigate tin whiskers. Lead-free doesn’t always mean non-toxic. Because other metal fumes are more or less toxic too.
There are often impurities like dirt, oil, oxidation, etc in or around the joint. Flux prevents oxidation and chemically cleanses the metal.
It basically prevents the formation of oxides. Rosin flux helps in the electrical contact and the mechanical strength of the joints.
What are the composition and properties of solder alloys?
Lead, tin and flux are widely found in solders. There are many solders available. Also, the mixing ratio of different metals also results in different solders. The percentage of additives also makes them differ from one another.
Antimony is used as an alloy metal in solders. It increases mechanical strength and prevents tin pests. But it doesn’t reduce wettability.
Copper, indium and bismuth cause the melting point to go lower. They also improve wetting properties.
Indium improves ductility. It is used to solder gold. They are expensive. We use silver for strength, specifically mechanical strength. But it lowers ductility.
There are specific combinations of metal ratios to use for specific applications to achieve strong joints.
What Metals Cannot Be Soldered?
Some metals, such as silver or titanium, are not easily solderable. These metals are usually too reactive to be used with substances like brazing flux.
Other metals that cannot be soldered include aluminum, steel, chromium and other alloys of nickel-based metal. This is because the melting point of these metals exceeds that of solder.
There are many types and ratios of mixtures of solders available. Lead-free, lead-based and what not! Despite the harmful effects of lead-based ones, they are still more reliable and preferred by professionals. The lead-free techniques can be used in electronic devices that meet environmental and health requirements.
Hopefully, this article was informative enough to answer your question “what metal is used for soldering?” If you have further inquiries, we suggest you get the help of a professional or research for your particular issue.