Guide to Different Types of Solder

What is Solder?

Solder is a metal alloy used to create strong electrical and mechanical bonds between components. It usually consists of elements like Lead (Pb), Tin (Sn), Silver (Ag), Bismuth (Bi), Antimony (Sb), Indium (In), and Cadmium (Cd).

Historically, lead-based solder (a mix of Lead and Tin) was widely used, particularly for electronics. However, due to the toxic nature of lead, industrial applications have shifted toward lead-free alternatives, especially following the UK's RoHS (Restriction of Hazardous Substances) Directive. Despite this, hobbyists and small-scale users still often prefer lead-based solder for its ease of use.

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Different Types of Solder & their Melting Points

The melting point of solder is crucial as it determines how effectively it can bond materials without damaging them. The table below lists different types of solder commonly used in UK industries, including electronics, plumbing, and jewellery:

UK Regulations and Standards

The UK adheres to strict guidelines for soldering materials. Under the RoHS Directive, lead-free solder is required for all commercial electrical and electronic equipment. The British Standard BS EN ISO 9453 specifies the composition and requirements for soft solders, ensuring safety and compliance in industrial applications.

Types of Solder by Composition

1. Lead-Based Solder

• A traditional mix of 60% Tin / 40% Lead is widely used in electronics.
• Benefits include easy flow and lower melting points.
• Now largely restricted in commercial applications due to lead toxicity.

2. Lead-Free Solder

• Made from Tin (Sn) with other elements like Silver (Ag) and Copper (Cu).
• Higher melting points than lead-based alternatives.
• Compliant with UK and EU RoHS laws.

3. Flux-Core Solder

• Contains a flux agent inside the core to remove oxidation and improve adhesion.
• Two main types:
  • Rosin Core Solder (for electronics; non-corrosive residue)
  • Acid Core Solder (for plumbing; requires cleaning after use)

4. Silver Alloy Solder

• Used in high-reliability applications such as aerospace and medical devices.
• Helps prevent silver migration, a common issue in older lead-based solders.

Types of Solder by Application

1. Electronics Soldering

• Lead-free solder is mandatory for commercial manufacturing in the UK.
• Rosin Core Solder is preferred for circuit boards.

2. Plumbing Solder

• Acid Core Solder is used for strong joints in copper pipes.
• Must comply with BS 6891 for gas and water pipework in the UK.

3. Automotive & Aerospace Soldering

• High-temperature solder is needed for extreme conditions.
• Must withstand vibration and thermal cycling.

4. Jewellery Soldering

• Silver-based solders create seamless bonds in jewellery making.
• Available in different flow temperatures for precision work.

Choosing the Right Solder for Your Needs

When selecting solder, consider:

• Application (electronics, plumbing, or metalwork?)
• Compliance (UK RoHS regulations apply to commercial work)
• Melting Temperature (low-temp for electronics, high-temp for heavy-duty soldering)
• Core Type (acid for plumbing, rosin for electronics, solid-core for manual flux application)

Final Thoughts

Soldering is an essential skill in various UK industries, from electronics and plumbing to automotive and jewellery making. With the shift towards lead-free alternatives due to safety and environmental regulations, understanding the different types of solder is more important than ever. Whether you're a DIY enthusiast or an industry professional, choosing the right solder ensures durability, compliance, and efficiency in your work.

If you need any assistance choosing the right solder for you please call our Sales Team on 01202 588900

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