What is pure tin solder used for?

What is the difference between pure tin, bright tin, and matte tin?

Pure tin plating

Pure tin has long been used in food packaging applications and as a cosmetic overlay. Recently, pure tin has been introduced as a non-toxic replacement for lead-containing solders. The maximum service temperature of pure tin solders is higher because of the higher melting temperature of tin (450°F / 232°C).

Pure tin plating Characteristics:

1. Soft, ductile, silvery-white metal
2. Not easily oxidized in air
3. Has good conductivity and corrosion resistance while enhancing the solderability of substrates
4. Non-toxic and non-carcinogenic

There are two types of electroplated pure tin:

Bright tin plating

Bright tin is coated in electroplating solutions containing brighteners, which are organic additives causing the formation of fine Grain structure deposits. Bright tin coatings have excellent cosmetic appearance; however, they are characterized by high internal stresses and contain a higher amount of organics.

Bright tin Characteristics:

1. Mirror-like reflectivity
2. average grain size below one micron
3. high degree of luster and is generally preferred for electrical contact applications, such as bus bars, terminals and switching components that are not soldered
4. If bright tin plating is soldered, the co-deposited organics in the deposit can burn, resulting in a de-wetting of the solder and a visible charring of the solder joint.

Matte tin plating

Matte tin coatings are made in electrolytes without the addition of brighteners. Matte tin has a dull appearance, but the level of internal stresses in matte tin depositions is much lower than it is in bright tin depositions. Matte tin (in contrast to bright tin) is characterized by low whiskers growing. Therefore, it is used in electronics.

Matte tin Characteristics:

1. a dull, semi-bright or satin-bright appearance
2. disperse reflectivity
3. existence of grains with an average size in the range of a few microns
4. the deposit is free of the co-deposited brighteners found in bright tin plating

KBA96474

PURE TIN

PHYSICAL PROPERTIES

• Solder Alloy Composition 100 Sn (weight %)
• Melting Temperature 231.9° C 
• 449.4° C
• Density 7·29 Mg m¯³
• Brinell Hardness 51 MPa
• CAS Registry Number 7440-31-5

Tin is not easily oxidized in air and is used to coat other metals to prevent corrosion.

Tin is available in solid wire, various bar sizes as well as cored wire. It is also available in fine wire.