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Welding Accessories and Consumables

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Electronic solder and other soldering accessories and consumables are the key to ensuring quality results on every soldering project. These items play a crucial role.

Tin for Electronics or Soldering Tin

Tin solder is the most commonly used consumable in electronics. Various solder alloys exist, all of which have tin as their main component.

Below are the most commonly used alloys and their key characteristics:

Tin Alloy for Electronics – 60% Sn 40% Pb

Historically, this has been the most widely used alloy. It features a lower melting point, which makes it easier to use for soldering heat-sensitive electronic components. It is very user-friendly. However, it is important to note that it contains lead, and the use of lead in soldering has been restricted or banned in many industrial sectors. One such area is consumer electronics, due to the harmful effects of lead on health and the environment.

Today, it is mainly used in maintenance and by hobbyists. Other sectors – such as military, aerospace, etc. – have implemented stricter regulations regarding the use of lead-based solder alloys.

Tin Alloy for Electronics – 60% Sn 38% Pb 2% Cu

This alloy is also commonly used. Tin is a soft metal with a low melting point, making it ideal for soldering. Lead is also soft and has a low melting point, but it is more toxic. Copper is a harder metal with a higher melting point, but it adds strength to the alloy and improves conductivity.

This alloy melts at around 183°C, making it suitable for a wide range of applications. It melts easily and offers good wettability, meaning it adheres well to metal surfaces. It also provides good corrosion resistance. This alloy is used in various applications, including:

Electronics soldering
Pipe soldering
Electrical component soldering
Jewellery soldering

It is a versatile and cost-effective alloy used in a wide range of applications. It is often referred to as a trimetal alloy or colloquially as trimetal tin. However, nowadays, other lead-free trimetal alloys are in use, and it is advisable not to use this name due to the confusion it may cause. As with the previous alloy, it contains lead and is subject to the same usage limitations as the 60/40 alloy.

Tin Alloy for Electronics – 96.5% Sn 3% Ag 0.5% Cu

Also known as SAC305 solder, this is a lead-free tin alloy commonly used in electronic applications. It consists of 96.5% tin, 3% silver and 0.5% copper.

It has several advantages over lead-based tin alloys, including:

Greater safety: Lead-free tin is less toxic.
Improved corrosion resistance: Silver and copper enhance corrosion resistance
Better thermal conductivity: Silver and copper improve thermal performance.

This alloy is used in a variety of electronic applications, such as:

Soldering electronic components (e.g. chips, resistors, capacitors)
PCB soldering (for printed circuit board layers)
Soldering electrical wires

The 96.5% Sn 3% Ag 0.5% Cu alloy is versatile and high-quality. It is a good option for applications requiring greater safety, corrosion resistance and thermal conductivity.

Tin Alloy for Electronics – 99% Sn 0.3% Ag 0.7% Cu

Also known as SAC0307 solder, this is another lead-free tin alloy commonly used in electronic applications. It consists of 99% tin, 0.3% silver and 0.7% copper. It has specific characteristics compared to leaded alloys such as SAC307. Key differences between SAC0307 and SAC305 include:

A lower melting point than SAC305, which makes soldering easier
Better corrosion resistance than SAC305, especially in humid environments
Similar thermal conductivity to SAC305
Due to its lower silver content, it is more economical than SAC305, though slightly less conductive (both thermally and electrically)

Overall, it is a good option for electronic applications requiring good corrosion resistance, thermal conductivity, and soldering ease.

What is Soldering Flux?

Soldering flux is a substance used during the soldering process to improve the quality of the joint between parts. Its primary role is to clean and protect metal surfaces from oxidation and other contaminants and to improve the wettability of the molten metal, helping it adhere to the base materials.

Flux helps to:

Remove oxidation: It cleans metal surfaces of oxides and contaminants that might interfere with soldering
Improve flow: It allows solder (such as tin in soft soldering) to spread and adhere more evenly
Reduce bubble formation: It prevents gas formation during soldering, thus reducing bubbles and defects

There are various types of flux used in tin soldering, and the choice depends on the type of soldering and metals involved. Some are used in soft soldering (e.g. for electronics), while others are used in brazing or arc welding. For best results, it is essential to choose the right flux and follow the manufacturer's guidelines.

Types of Soldering Flux

Flux can be classified according to its chemical composition, physical form, or function.

By chemical composition:

Organic fluxes: Mainly composed of organic substances such as resin, alcohol, and oils. These are most commonly used in soft soldering due to their ease of use and performance.
Inorganic fluxes: Composed mainly of inorganic materials such as oxides, salts, and silicates. These withstand higher temperatures and are used in brazing and arc welding.

By physical form:

Liquid fluxes: The most common form. They may appear as liquids, pastes, or gels, and are applied with a brush, sponge, or flux pen.
Paste fluxes: Similar to liquid fluxes but thicker in consistency. Applied with a brush or sponge.
Solid fluxes: Appear as powders or granules. Applied using a flux pen or flux gun.

By function:

Deoxidising fluxes: Used to remove oxidation from metal surfaces before soldering
Protective fluxes: Used to prevent oxidation during soldering
Wetting fluxes: Used to enhance the flow and adhesion of molten solder

Choosing the Right Soldering Flux

The choice of flux depends on several factors such as the type of soldering, the metals involved, and the working conditions. As a general rule:

Use organic fluxes for soft soldering
Use inorganic fluxes for brazing and arc welding
For humid environments, use a flux with a high deoxidising content
For high-temperature applications, opt for a flux with a high content of protective agents