tinsilver

Tinsilver refers to a binary alloy of tin (Sn) and silver (Ag) used primarily as a lead-free solder or filler metal. In practice, “tin-silver” solders are designed to replace traditional tin-lead solders in electronics and related industries.

Composition and variants

The silver content in tin-silver solders typically ranges from about 1% to several percent. A notable eutectic composition occurs at roughly 3.5% Ag, which produces a relatively low and sharp melting point around 221°C for the Sn-Ag system. In electronics, many lead-free solders combine tin with silver and copper (for example, Sn-Ag-Cu, or SAC alloys such as Sn96.5-Ag3.0-Cu0.5), which have melting ranges around 217–221°C. Pure binary Sn-Ag alloys exist but are less common in mass production. Silver addition increases hardness, strength, and creep resistance, and improves corrosion resistance, at the cost of higher material price and slightly higher melting temperatures compared with some lead-containing solders.

Properties and processing

Tin-silver solders generally wet copper and many metallurgical surfaces well when proper flux is used. They require appropriate heating profiles and clean surfaces to avoid poor joints. As lead-free alternatives, they are favored under environmental regulations, but wetting, solderability, and joint reliability depend on alloy composition, flux, and processing conditions. Tin whisker formation, a risk with tin-containing solders, can be influenced by alloy choice and packaging.

Applications

Tin-silver alloys are widely used in electronics synthesis and manufacturing for surface-mount and through-hole soldering, and are also used in jewelry and some brazing filler contexts where lead-free options are preferred.