Tinapinnoitteissa

Tinapinnoitteissa refers to coatings in which a thin layer of tin is deposited on a metal surface. The term is used in Finnish industry to describe tin plating and tin-coated products, such as tinplate steel and various electronic or mechanical components. Tin coatings are chosen for their combination of solderability, corrosion resistance, and relatively low toxicity.

Methods and types: The most common tin coatings are electrolytic tin plating, where tin is deposited from a tin-containing solution using electrical current; immersion tin plating, where tin deposits without external current through a chemical reaction; and hot-dip tinning, in which steel is coated by dipping into molten tin to form a continuous layer. The resulting coating thickness is typically a few micrometres, enough to protect the base metal while remaining workable for further processing.

Properties and limitations: Tin coatings provide a ductile, solderable surface and improve resistance to corrosion in neutral or mildly acidic environments. They can form tin oxide on exposure to air, which influences appearance and conductivity over time. In electronics, a known reliability consideration is whisker growth, where tin filaments can extend from a pure tin surface and affect performance. Tin coatings can also be susceptible to certain types of galvanic corrosion if paired with incompatible metals.

Applications: Tinapinnoitteissa are widely used for food packaging via tinplate steel, as well as for protective finishes on hardware and in electrical components such as connectors and leadframes. In electronics, tin plating is common as a finishing layer or a starting surface for soldering before lead-free solder technologies became prevalent.

History and regulation: Tin plating has a long history dating to the 19th century and remains relevant under modern regulations, including RoHS, which influences the choice of tin finishes in lead-free solder contexts.