What are solders and where are they used?

What are solders?

Solders are metal alloys designed to join parts using the soldering method. Unlike welding, in soldering the base metal does not melt — only the solder melts, filling the gap between the parts and, after solidifying, forming a strong and герметичное (airtight) connection.

Main types

Solders are classified according to several criteria: by melting point (low‑melting and high‑melting), by the content of main components, and by the presence of alloying additives.

Tin‑lead solders (POS) are the most common group. These are alloys based on tin and lead, to which antimony, bismuth, indium, and other metals may be added. The marking of such solders includes a number indicating the percentage of tin content:

• POS‑30 (30 % tin) — used for soldering and tinning parts made of zinc, copper, brass, bronze, and tinplate. Melting point: 183–238 °C.
• POS‑40 (40 % tin) — applied for soldering copper wires, iron, brass, silver, and galvanized parts. Melting point: 183–238 °C.
• POS‑61 (61 % tin) — one of the most in‑demand solders for tinning and soldering electrical and radio equipment, printed circuit boards, and precision instruments with highly airtight joints. Melts at 183–190 °C.
• POS‑90 (90 % tin) — has good fluidity, completely fills all irregularities, and produces airtight joints. Used for manufacturing food‑grade and medical utensils, as well as for creating microcircuits.

Antimony‑containing and low‑antimony solders (POSSu) are distinguished by the addition of antimony, which increases the hardness and strength of the joint. Low‑antimony solders (0.05–0.5 % Sb) are used for electrical equipment; antimony‑rich solders (1.5–2.0 % Sb) are used for components subject to vibration and loads, for example, in the automotive industry.

Lead‑free and low‑melting solders are modern eco‑friendly alternatives, as well as special alloys based on bismuth and indium for soldering components that are sensitive to overheating.

Properties of solders

The quality of a solder is determined by several key characteristics:

• Melting point — the higher the tin content, the lower the melting point. For POS‑61, it is 183–190 °C; for POS‑30, it is 183–238 °C.
• Fluidity — the ability of molten solder to fill even the smallest gaps and irregularities in the surfaces being soldered.
• Electrical conductivity — important for soldering electronic components and printed circuit boards.
• Strength and ductility — determine the reliability of the joint under vibration and mechanical loads.
• Corrosion resistance — especially important for solders used in the food and medical industries.

Applications

Due to the variety of compositions and properties, solders are used in almost all industries:

• Electronics — soldering printed circuit boards, mounting electronic components, creating microcircuits and precision instruments with highly airtight joints.
• Automotive industry — joining electrical wiring, soldering radiators and heat exchangers, tinning parts.
• Instrument making — manufacturing precision measuring instruments where joint tightness is critical.
• Food industry — tinning and soldering internal seams of food‑grade utensils and medical equipment.
• Electrical engineering — soldering windings of electrical machines, cable products, and contact surfaces.
• Aviation industry — soldering critical components that operate under high loads.

Solders are produced in various forms: ingots (bars), rods with a diameter of 8–10 mm, wire from 0.5 to 5 mm, flux‑cored tubes from 1.2 mm, and tape. This allows selecting the optimal format for any technological process — from manual soldering to automated production.

Production and quality control at the Novosibirsk Tin Plant

The manufacturing technology at the Novosibirsk Tin Plant is based on strict adherence to proportions and thorough quality control of the raw materials. The plant produces solders from its own mineral raw materials, which guarantees a stable chemical composition and compliance with GOST 21931‑76. During melting and casting, modern equipment and proven methods are used to ensure consistent product quality.

The company has implemented a modern quality control system at every stage of production. The latest‑generation equipment and technologies that meet international standards are used for manufacturing. Each batch of products is accompanied by a full set of documentation, and shipments are made exactly on time in accordance with the contract.

Advantages of purchasing from the Novosibirsk Tin Plant

• Quality guarantee — products undergo multi‑stage control and fully comply with GOST 21931‑76.
• Wide range — tin‑lead (POS), low‑antimony and antimony‑rich (POSSu), lead‑free and low‑melting, and special alloys.
• Own raw materials — stable chemical composition, independence from imports.
• Flexible delivery terms — individual solutions are possible regarding order volume and deadlines.
• Delivery across Russia and the CIS — shipping to any region of the Russian Federation and neighbouring countries.

The Novosibirsk Tin Plant provides its customers not only with reliable products but also with professional support — from selecting the optimal alloy to consulting on its application.