Tin pest
Encyclopedia
Tin pest is an autocatalytic
, allotropic
transformation of the element tin
, which causes deterioration of tin objects at low temperatures. Tin pest has also been called tin disease, tin blight or tin leprosy (Lèpre d'étain).
It was observed in medieval Europe
that the pipe
s of church pipe organ
s were affected in cool climates. As soon as the tin began decomposing, the process accelerated.
With the adoption of the Restriction of Hazardous Substances Directive
(RoHS) regulations in Europe, and similar regulations elsewhere traditional lead/tin solder
s have been replaced by solders containing primarily tin, making prevention of tin pest (and related problems such as tin whiskers) a modern (21st century) technological challenge.
(about 56 degrees Fahrenheit
) and below, pure tin transforms from the (silvery, ductile) allotrope
of β-form white tin to brittle, α-form grey tin. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures ~-30 degrees Celsius aids the initiation. There is also a volume increase associated with the phase change. Eventually the α-form decomposes into powder, hence the name tin pest.
The decomposition will catalyze itself, which is why the reaction speeds up once it starts; the mere presence of tin pest leads to more tin pest. Tin objects at low temperature
s will simply disintegrate.
hoped to be the first to reach the South Pole
, but was beaten by Norwegian
explorer Roald Amundsen
. On foot, the expedition trudged through the frozen desert
s of the Antarctic
, making for caches of food
and kerosene
deposited on the way in. In early 1912, at the first cache, there was no kerosene; the cans — solder
ed with tin — were empty. The cause of the empty tins could have been related to tin pest, and some observers blame poor quality soldering, although tin cans over eighty years old have been discovered in Antarctic buildings with the soldering in good condition.
(RoHS) regulations in Europe and California banning most uses of lead
, and similar regulations elsewhere, the problem of tin pest has returned, since some manufacturers now use pure tin, but previously used tin/lead alloys. For example, the leads
of some electrical and electronic components are plated with pure tin. In cold environments, this can change to α-modification grey tin, which is not electrically conductive, and fall off the leads. After reheating, it changes back to β-modification white tin, which is electrically conductive, and can cause electrical short circuit
s and failure of equipment. Such problems can be intermittent as the powdered particles of tin move around. Tin pest can be avoided by alloy
ing with small amounts of electropositive metals or semimetals soluble in tin's solid phase e.g. antimony
or bismuth
, which prevent the decomposition. Silver
, indium
, and lead
have also been used, but lead is not soluble in tin's solid phase.
Autocatalysis
A single chemical reaction is said to have undergone autocatalysis, or be autocatalytic, if the reaction product itself is the catalyst for that reaction....
, allotropic
Allotropy
Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, known as allotropes of these elements...
transformation of the element tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
, which causes deterioration of tin objects at low temperatures. Tin pest has also been called tin disease, tin blight or tin leprosy (Lèpre d'étain).
It was observed in medieval Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
that the pipe
Organ pipe
An organ pipe is a sound-producing element of the pipe organ that resonates at a specific pitch when pressurized air is driven through it. Each pipe is tuned to a specific note of the musical scale...
s of church pipe organ
Pipe organ
The pipe organ is a musical instrument that produces sound by driving pressurized air through pipes selected via a keyboard. Because each organ pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre and volume throughout the keyboard compass...
s were affected in cool climates. As soon as the tin began decomposing, the process accelerated.
With the adoption of the Restriction of Hazardous Substances Directive
Restriction of Hazardous Substances Directive
The Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment 2002/95/EC was adopted in February 2003 by the European Union. The RoHS directive took effect on 1 July 2006, and is required to be enforced and become law in each member state...
(RoHS) regulations in Europe, and similar regulations elsewhere traditional lead/tin solder
Solder
Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece.Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of . It is commonly used in electronics and...
s have been replaced by solders containing primarily tin, making prevention of tin pest (and related problems such as tin whiskers) a modern (21st century) technological challenge.
Allotropic transformation
At 13.2 degrees CelsiusCelsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
(about 56 degrees Fahrenheit
Fahrenheit
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
) and below, pure tin transforms from the (silvery, ductile) allotrope
Allotropy
Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, known as allotropes of these elements...
of β-form white tin to brittle, α-form grey tin. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures ~-30 degrees Celsius aids the initiation. There is also a volume increase associated with the phase change. Eventually the α-form decomposes into powder, hence the name tin pest.
The decomposition will catalyze itself, which is why the reaction speeds up once it starts; the mere presence of tin pest leads to more tin pest. Tin objects at low temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s will simply disintegrate.
Scott expedition to Antarctica
In 1910 British polar explorer Robert ScottRobert Falcon Scott
Captain Robert Falcon Scott, CVO was a Royal Navy officer and explorer who led two expeditions to the Antarctic regions: the Discovery Expedition, 1901–04, and the ill-fated Terra Nova Expedition, 1910–13...
hoped to be the first to reach the South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
, but was beaten by Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
explorer Roald Amundsen
Roald Amundsen
Roald Engelbregt Gravning Amundsen was a Norwegian explorer of polar regions. He led the first Antarctic expedition to reach the South Pole between 1910 and 1912 and he was the first person to reach both the North and South Poles. He is also known as the first to traverse the Northwest Passage....
. On foot, the expedition trudged through the frozen desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
s of the Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
, making for caches of food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
and kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
deposited on the way in. In early 1912, at the first cache, there was no kerosene; the cans — solder
Solder
Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece.Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of . It is commonly used in electronics and...
ed with tin — were empty. The cause of the empty tins could have been related to tin pest, and some observers blame poor quality soldering, although tin cans over eighty years old have been discovered in Antarctic buildings with the soldering in good condition.
Napoleon's buttons
The story is often told of Napoleon's men freezing in the bitter Russian winter, their clothes falling apart as tin pest ate the buttons. Whether failing buttons were indeed a contributing factor in the failure of the invasion remains disputed; critics of the theory point out that the tin used would have been quite impure and thus more tolerant of low temperatures. Laboratory tests provide evidence that the time required for unalloyed tin to develop significant tin pest damage at lowered temperatures is about 18 months, which is more than twice the length of Napoleon's Russian campaign.Modern tin pest since adoption of RoHS
With the adoption of the Restriction of Hazardous Substances DirectiveRestriction of Hazardous Substances Directive
The Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment 2002/95/EC was adopted in February 2003 by the European Union. The RoHS directive took effect on 1 July 2006, and is required to be enforced and become law in each member state...
(RoHS) regulations in Europe and California banning most uses of lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, and similar regulations elsewhere, the problem of tin pest has returned, since some manufacturers now use pure tin, but previously used tin/lead alloys. For example, the leads
Lead (electronics)
In electronics, a lead is an electrical connection consisting of a length of wire or soldering pad that comes from a device. Leads are used for physical support, to transfer power, to probe circuits , and to transmit information...
of some electrical and electronic components are plated with pure tin. In cold environments, this can change to α-modification grey tin, which is not electrically conductive, and fall off the leads. After reheating, it changes back to β-modification white tin, which is electrically conductive, and can cause electrical short circuit
Short circuit
A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....
s and failure of equipment. Such problems can be intermittent as the powdered particles of tin move around. Tin pest can be avoided by alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
ing with small amounts of electropositive metals or semimetals soluble in tin's solid phase e.g. antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
or bismuth
Bismuth
Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead...
, which prevent the decomposition. Silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, indium
Indium
Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...
, and lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
have also been used, but lead is not soluble in tin's solid phase.
See also
- Gold-aluminium intermetallicGold-aluminium intermetallicA gold-aluminium intermetallic is an intermetallic compound of gold and aluminium that occurs at contacts between the two metals. These intermetallics have different properties than the individual metals which can cause problems in wire bonding in microelectronics...
- giving rise to Purple plague or White plague, another failure mode for electronic components due to the formation of a crystalline substance. - Zinc pestZinc pestZinc pest, , is a destructive, intercrystalline corrosion process of zinc alloys containing lead impurities. It was first discovered to be a problem in 1923....
- decay of zinc by an unrelated intercrystalline corrosion process.
External links
- tin pest, transformation of beta tin into alpha modification (grey tin) Time lapse video of tin pest on ingot via www.youtube.com