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Leaded Solder Wire & Rosin Core Leaded Solder

Leaded solder wire is selected based on application requirements, core type, and wire diameter. Rosin core solder is commonly used for electrical connections and circuit work, while different diameters are chosen based on the level of precision and control required.

This type of solder is typically used in electronics and controlled environments where consistent handling and predictable results are important.
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Leaded Solder Wire for Precision Electronics & Electrical Work

Leaded solder wire is used for electronics and precision electrical work where control, consistency, and ease of use are critical. Compared to lead-free options, leaded solder flows more easily and works at lower temperatures, making it the preferred choice for circuit boards, electrical repair, and detailed soldering applications.

Rosin core leaded solder is commonly used for electrical connections to improve flow and reduce the need for additional flux. Wire diameter also impacts performance—smaller diameters are used for fine circuit work, while larger diameters are better suited for electrical assembly and higher-volume soldering.

At WeldingMart, you can buy leaded solder wire in multiple diameters and core types to match your application. Our in-stock selection is ready to ship and supports fast turnaround for electronics repair and precision assembly. Explore our full range of welding wire & filler metals or shop lead free solder wire for compliance-driven and plumbing applications.

Benefits

  • Easier to work with at lower temperatures for circuit boards and electrical connections
  • Smooth flow and reliable wetting for consistent, high-quality solder joints
  • Multiple diameters and rosin core options available for precision and assembly work

Frequently Asked Questions

What is rosin core solder and when should I use it?
Rosin core solder is a wire solder with a hollow center filled with rosin flux. The flux flows ahead of the solder as you heat the joint, cleaning the surface and promoting wetting without needing separately applied flux. It is the standard choice for electronics and electrical work — rosin flux residues are non-hygroscopic, electrically non-conductive, and not corrosive after cooling, making them safe to leave in place on circuit boards.
What is the difference between 60/40 and 63/37 tin-lead solder?
60/40 solder (60% tin, 40% lead) has a mushy range between 183°C and 190°C (361–374°F) — it is partially solid and partially liquid through that range. 63/37 (63% tin, 37% lead) is the true eutectic composition: it melts and solidifies at a single temperature of 183°C (361°F), with no mushy phase. The eutectic 63/37 is preferred for fine electronics work because the instant solidification reduces the chance of disturbed (cold) joints during cooling.
Can I use rosin core solder for copper plumbing?
No. Rosin flux is too mildly active to adequately clean copper tube and fittings for plumbing work, and the rosin residue trapped in a closed water system can cause long-term issues. For copper plumbing, use a water-soluble paste flux applied externally with a solid wire solder, and flush the system after soldering to remove flux residue.
What precautions are required when using leaded solder?
Lead is a health hazard — wash hands thoroughly after handling leaded solder and before eating or drinking. Solder in well-ventilated areas to avoid inhaling flux fumes, which can cause respiratory irritation regardless of lead content. Leaded solder is restricted or banned from many applications in the EU under RoHS; confirm regulatory requirements for your end-use application before choosing a leaded alloy.
What solder alloy is best for high-temperature applications near the limits of tin-lead soldering?
For the highest end of tin-lead performance, high-lead alloys (e.g., 10/90 or 5/95 Sn-Pb, liquidus around 299–314°C / 570–597°F) are used in elevated-temperature service. The AWS handbook also lists tin-silver alloys (Sn-3.5Ag) as bridging options with better heat resistance than standard 60/40. Beyond about 300°C (570°F), brazing alloys rather than solders are the correct choice.