Due to the oxidation process on metals, Metals get deteriorated and it's an irreversible phenomenon that is what we call corrosion. We have seen it in our daily use of metals but if we talk about the electronic & electrical industrial application it is more often seen that the point of solder gets rusted which results in the malfunctioning of electronic gazets.
Having a huge contribution to the electrical and electronic industrial application "Tin" is known for its all-time use. Usually, It is used for making bronze. Tin has some great property of high corrosion resistance and low melting point. Apart from this property environment shows its existence on the corrosion of Tin. Which is regularly shown when we look out on soldering point of any solderable applications like any motherboard or any electronic item.
Even the atmospheric air, having moisture and oxygen, can start this process, on Tin surface. As Tin is used in soldering along with Lead and other metals. So it is very important to have a technical specification of Tin, which will help us to select the composition of the alloy in the soldering process
Some of the composition which is used in the industry according to the applications are as -
As you can see that there are different Number is along with Sn (Tin) like 99,96,95,63,60,50 these number shows how much of TIN material is used in the particular composition. Different composition gets differently affected by the atmosphere.
As Corrosion is an electrochemical process that appears in several forms, such as chemical corrosion and atmospheric corrosion. When atmospheric moisture in acidic form comes in contact with metals, such as TIn, Pb, Cu, Ag etc. rust begins to form. The metals make oxides by contact of air or moisture and generate a layer around the surface which protects further corrosion but in a long time metal gets slowly eroded and its outer layer depleted which results in malfunctioning of electronic instruments.
In Atmosphere there are several gases whcih affects the metals like Tin, Lead, Silver, Copper etc. The main gas is Oxygen and sulpher. They mainly used to make oxide of there respective gases.
When the gases comes in the contact of metals like Tin it tends to make a outer layer to protect the metals from further depletion of metals. Although it is a slow process in dry air because the thickness of the oxide grow according to a logarithmic law at temperatures up to about 160°C and according to a parabolic law at higher temperatures, for which the oxide identified as SnO.
Oxidation of tin in dry air is slow; the metal remains bright and interference colours are not developed below about 180°C. On a rolled tin surface heated in air [20,21], the thickness of the oxide grew according to a logarithmic law at temperatures up to about 160°C and according to a parabolic law at higher temperatures, for which the oxide was identified as SnO.
The oxide identified as SnO at temperatures down to 75°C. However, a mixture of SnO and SnO2 is formed in dry air at lower temperatures and or in humid air, at temperatures up to at least 100°C. Electrochemical reduction analysis on tin oxidised in dry air at 125 and 150°C confirmed the presence of SnO with a thin surface layer of SnO2.