What is solder and soldering?

Soldering is the process of joining two metals together using a filler element with a high melting point. This filler element is the solder, which is a metal alloy. The alloys within solder usually contains the elements: Lead, Tin, Silver, Bismuth, Antimony Indium & Cadmium.

Lead and Tin are the main elements of that are used in a variety of Solders specifically for soft soldering. However the use of lead based solder is reducing to its environmental factor, therefore the popular growth in lead free solder. Even though the use of lead based solder is popular amongst small scale jobs.

The main criteria for choosing the type of solder is that the melting point of the solder should be lower than the melting point of the metal you are trying to join together.

Types of Solder – Alloy

Lead-based solder

Lead based solder is a type of solder made where the material is lead and tin based. You can get high grade solder where there is more tin than lead in the alloy or the general purpose solder where 99% of the alloy is lead with some tin. These types of solder are mainly used for electronic manufacturing applications to form a strong bond between the joints of other metals. Lead-based solder is not used with pipes that handle water.

Lead-free solder

Lead-free solders tend to be used in the plumbing industry regularly due to the element lead being poisonous and hazardous to people, especially children. Lead-free solders has a higher melting point than the solders that are lead based. Some of the examples of lead-free solders are:

Tin-Antimony solder: This type of solder contains 95% tin and 5% antimony. This type of solder is designed for plumbing uses where there is extreme temperature and frequent movement present. The melting range for this solder is 450°F to 464°F.

Copper-Tin solder: This type of solder contains 97% tin and 3% copper. This solder is designed for joining copper and brass plumbing parts together. The melting range for this solder is 440°F to 572°F.

Silver-bearing solder: This solder is mixture of 4 different alloys, silver, copper, bismuth and tin. This solder is used within low-lead brass applications. It has a melting range of 420°F to 460°F.

Other examples of lead-free solders include indium solder, spelter brass solder, platinum solder, gold solder.

Flux-Core Solders

Flux core solder is also known wire solder that has flux in the centre of the wire. Without this flux in the wire, this type of solder becomes very difficult to use. The metal surface that are usually soldered on have an oxide laser and heating these surfaces during the soldering process increases its thickness. The flux helps go through the oxide and clean the metal surface so the solder can bond correctly. The flux will melt first, the metal surfaces for a better joint.

 

Types of Solder – Core Style

There are 3 different types of core that are used within the solder. These are:

Acid Core Solder

Acid core solder is solder that is in the form of wires that created with an acid-based flux core. The acid-based flux works in removing the metal oxide layer formed on the surface of the metal and prevents further oxidation of the metal. Because of this, it helps produces joints that are very strong and tough to break.

Rosin Core Solder

Rosin core solder is solder that is in the form of wires that created with an a flux-core made from rosin. The advantage of using rosin core solders is that it does not cause corrosion. So it is most commonly used in soldering electrical appliances because it is difficult to remove the residue in electrical components.

Solid Core Solder

This type of solder wire is a wire that does not contain any flux within it and only contains solder alloy instead of a hollow core unlike the acid and rosin core. This type of solder require applying flux separately.

Types of Solder – Form

The most common type of solder are solder wires that is wrapped around a spool. Solder also comes in others forms such as:

• Solder sticks
• Solder strips
• Solder pellets
• Solder rods
• Solder foil
• Solder rings
• Solder ribbons