Weller's Solder, or solder wire, is a fusible metal alloy with a low temperature melting point used to permanently join two metals that have a higher melting point. Soldering is a process commonly used in the electronics industry for PCBs and electronics components, jewellery manufacturing and pipework in plumbing, with the majority of soldering carried out through the use of a soldering iron.

Our range of Weller solder wire has a variety of wire diameters (ranging from 0.2mm to 1.6mm) which have leadfree content.

What is solder made of?

The alloys used in solder vary depending on the manufacturer and the intended application, as different applications require different materials.

• Soft solder is commercially available at varying concentrations of tin, ranging from 5% to 70%. Higher percentages of tin provide greater tensile strength, with a 60/40 balance being a popular composition.
• Lead-free solder is also available, created due to the call to remove or reduce hazardous materials in consumer electronics, which often has a lower melting point than lead-based alloys. Lead-free solder wire may contain copper, zinc, tin, silver, bismuth, antimony and/or traces of other materials depending on its intended use.

What is flux?

L0, M1, and rosin flux are different types of flux used in soldering to aid in the formation of strong and reliable joints by cleaning and preparing the surfaces being soldered. Here's a detailed overview of each:

L0 Flux

• Type: No-Clean Flux
• Characteristics: L0 flux is classified as a low-activity, no-clean flux. It leaves behind minimal residue that is non-corrosive and non-conductive, which usually doesn't need to be cleaned off after soldering.
• Usage: Ideal for applications where cleaning the soldered joints is difficult or undesirable. Commonly used in high-volume electronics manufacturing, especially for consumer electronics where reliability and minimal maintenance are critical.

M1 Flux

• Type: Halide-Free, Organic Flux
• Characteristics: M1 flux is a type of flux that is free from halides (which can be corrosive) and organic-based. It is generally classified under the ROL0 or ORL0 categories, indicating a no-clean, low-residue type of flux.
• Usage: Suitable for sensitive electronic applications where the presence of halides could lead to corrosion and long-term reliability issues. Often used in military, aerospace, and high-reliability applications.

Rosin Flux

• Type: Rosin-Based Flux
• Characteristics: Made from natural rosin (a solid form of resin obtained from pine trees) combined with other chemicals to improve its effectiveness. Rosin fluxes are categorised by their activity levels:
• R (Rosin): Pure rosin, low activity, leaves a residue that is non-corrosive.
• RMA (Rosin Mildly Activated): Contains small amounts of activators to improve cleaning efficiency, and leaves a slightly more active residue that is still generally non-corrosive.
• RA (Rosin Activated): Contains more aggressive activators for better cleaning, but the residue can be corrosive and usually needs to be cleaned off.
• Usage: Widely used in traditional electronics soldering, especially where post-soldering cleaning is feasible. RMA flux is popular in both consumer and industrial electronics, while RA flux is used when more aggressive cleaning is needed but also requires careful post-soldering cleaning.

What forms of Weller solder are there?

Weller solder comes in wire form, with a range of wire diameters available to suit various applications and joints. The wire form is often used for electrical maintenance but also is useful for Connector Assembly, Wire Splicing and Automotive electronics.