Tin electroplating, also referred to as electro-tinning, is a type of surface treatment process. It produces a metallic coating of tin on the surface of metal components. We produce the coating in one of two electrolytes. One option is an alkaline solution producing a matt pure tin finish. The alternative is an acid solution containing organic brighteners. This second option produces a bright finish.
What is Tin Plating used for?
We often use tin electroplating for functional applications. However, in some applications the appearance of the surface is also important. This coating has a good resistance to oxidation in moderately corrosive environments. Many will apply it to equipment and machines used in the food industry. The main application of the tin coating, however, is for surfaces on which soldering is necessary – as well as electric contacts and switchgear.
The soft character and corrosion durability of the tin coating are appealing factors. It results in low and stable contact resistance, compared to copper and brass surfaces. With copper and brass, the contact resistance with time increases due to the formation of a thin layer of corrosion products.
Tin coatings have poor solder-ability. They are usually deposited directly on zinc rich copper alloys such as brass. This is because the tin coating diffuses into the zinc rich areas of the brass. As a result, this also decreases the resistance of the coating to oxidation. You can avoid diffusing tin plating by applying a nickel or pure copper barrier layer before the tin plating.
Electro-tinning can under certain circumstances spontaneously form long, thin (1-3 urn) threads of tin, so-called tin whiskers. This can create difficulties with current-division or short-circuiting in electronic components. An undercoat of nickel, applied before the tin coating, counteracts the formation of whiskers.
Corrosion Behaviour of Tin Coatings
Tin is a base metal compared to copper, copper-alloy and nickel. Therefore, it is capable of protecting these metals where minor damages and perforations occur in the tin coating. This is a principal which is known as cathodic protection.
The coating is more noble metal than steel under atmospheric conditions. However, damage and voids can penetrate the tin coating. This will result in galvanic corrosion. Additionally, rust will form on the steel surface where it is being exposed to the environment. High tin thickness or undercoats of nickel reduces the amount of porosity to base metal of the coating. However, we recommend that your components are manufactured in a corrosion resistant material if they will be under highly corrosive conditions. This is also the case if they are required to have a long service life.
Application Data for Tin (Sn)
IMDS number: 756885
Melting point: 2320 C
Volume weight: 7,3 g/cm3
Max application temperature for tin: 1000 C
Specifications for Tin Coatings
We carry out tin electroplating in accordance with the standards BS 1872, ISO 2093 (1986), as well as many industry-specific specifications.
If you would like to find out more about our tin electroplating services or zinc nickel plating, then head to our website today. Or, call to speak to a member of our helpful and friendly team. We offer a wide range of electroplating services including zinc nickel plating on to stainless steel.
If you have found this blog helpful, you may wish to read our previous blog on Zinc Nickel Coating.