Tin pest

Last updated
Tin medal affected by tin disease PSM V83 D034 Two hundred year old medal affected by tin disease.png
Tin medal affected by tin disease

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).[ citation needed ]


It was observed in medieval Europe that the pipes of pipe organs were affected in cool climates. As soon as the tin began decomposing, the process accelerated.[ citation needed ]

With the adoption of the Restriction of Hazardous Substances Directive (RoHS) regulations in Europe, and similar regulations elsewhere, traditional lead/tin solder alloys in electronic devices have been replaced by nearly pure tin, introducing tin pest and related problems such as tin whiskers. [1] [2]

Allotropic transformation

At 13.2 °C (about 56 °F) and below, pure tin transforms from the silvery, ductile metallic allotrope of β-form white tin to the brittle, nonmetallic, α-form grey tin with a diamond cubic structure. 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 of roughly −30 °C aids the initiation. There is also a large volume increase of about 27% associated with the phase change to the nonmetallic low temperature allotrope. This frequently makes tin objects (like buttons) decompose into powder during the transformation, hence the name tin pest. [3]

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 temperatures will simply disintegrate.

Possible historical examples

Scott expedition to Antarctica

In 1910 British polar explorer Robert Scott 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 deserts of the Antarctic, marching for caches of food and kerosene deposited on the way. In early 1912, at the first cache, there was no kerosene; the cans – soldered with tin – were empty. The cause of the empty tins could have been related to tin pest. [4] Some observers blame poor quality soldering, as tin cans over eighty years old have been discovered in Antarctic buildings with the soldering in good condition.[ citation needed ]

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. This appears to be an urban legend, as there is no evidence of any failing buttons, and thus they cannot have been a contributing factor in the failure of the invasion. [5] Uniform buttons of that era were generally bone for enlisted, and brass for officers. [6] Critics of the theory point out that any tin that might have been used would have been quite impure, and thus more tolerant of low temperatures. Laboratory tests of 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 the invasion. [4] Nevertheless, some of the regiments in the campaign did have tin buttons and the temperature reached sufficiently low values (below −40 °C or °F). [5] In the event, none of the many survivors' tales mention problems with buttons and it has been suggested that the legend is an amalgamation of a case of disintegrating Russian tin buttons in an army warehouse in the 1860s [7] and the desperate state of Napoleon's army, having turned soldiers into ragged beggars. [5] [8]

Modern tin pest since adoption of RoHS

Re-melted tin affected with tin pest is poured into ingot molds at Rock Island Arsenal Joint Manufacturing and Technology Center, Rock Island, Illinois, in 2017. Re-melted tin affected with tin pest is poured into ingot molds at Rock Island Arsenal Joint Manufacturing and Technology Center, DVIDS3878892.jpg
Re-melted tin affected with tin pest is poured into ingot molds at Rock Island Arsenal Joint Manufacturing and Technology Center, Rock Island, Illinois, in 2017.

With the adoption of the Restriction of Hazardous Substances Directive (RoHS) regulations in Europe, California banning most uses of lead, and similar regulations elsewhere, the problem of tin pest has returned, [9] since some manufacturers who previously used tin/lead alloys now use predominately tin based 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 falls off the leads. After reheating, it changes back to β-modification white tin, which is electrically conductive. This cycle can cause electrical short circuits and failure of equipment. Such problems can be intermittent as the powdered particles of tin move around. Tin pest can be avoided by alloying with small amounts of electropositive metals or semimetals soluble in tin's solid phase, e.g. antimony or bismuth, which prevent the phase change.

See also

Related Research Articles

Solder Alloy used to join metal pieces

Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics.

Tin Chemical element, symbol Sn and atomic number 50

Tin is a chemical element with the symbol Sn and atomic number 50. Tin is a silvery-colored metal.

Printed circuit board Board to support and connect electronic components

A printed circuit board (PCB) or printed wiring board (PWB) is a laminated sandwich structure of conductive and insulating layers. PCBs have two complementary functions. The first is to affix electronic components in designated locations on the outer layers by means of soldering. The second is to provide reliable electrical connections between the component's terminals in a controlled manner often referred to as PCB design. Each of the conductive layers is designed with an artwork pattern of conductors that provides electrical connections on that conductive layer. Another manufacturing process adds vias, plated-through holes that allow interconnections between layers.

Eutectic system Mixture with a lower melting point than its constituents

A eutectic system from the Greek εὐ- and τῆξῐς, also known as a eutectic mixture, is a homogeneous mixture of substances that melts or solidifies at a single temperature that is lower than the melting point of any of the constituents. This temperature is known as the eutectic temperature, and is the lowest possible melting temperature over all of the mixing ratios for the involved component species. On a phase diagram, the eutectic temperature is seen as the eutectic point.

Flux (metallurgy)

In metallurgy, a flux is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining.

Restriction of Hazardous Substances Directive European Union directive restricting ten hazardous materials

The Restriction of Hazardous Substances Directive 2002/95/EC, short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union.

Wave soldering

Wave soldering is a bulk soldering process used for the manufacturing of printed circuit boards. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave. As the circuit board makes contact with this wave, the components become soldered to the board. Wave soldering is used for both through-hole printed circuit assemblies, and surface mount. In the latter case, the components are glued onto the surface of a printed circuit board (PCB) by placement equipment, before being run through the molten solder wave. Wave soldering is mainly used in soldering of through hole components.

Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish.

Whisker (metallurgy) Phenomenon in electrical devices

Metal whiskering is a phenomenon which occurs in electrical devices when metals form long whisker-like projections over time. Tin whiskers were noticed and documented in the vacuum tube era of electronics early in the 20th century in equipment that used pure, or almost pure, tin solder in their production. It was noticed that small metal hairs or tendrils grew between metal solder pads, causing short circuits. Metal whiskers form in the presence of compressive stress. Germanium, zinc, cadmium, and even lead whiskers have been documented. Many techniques are used to mitigate the problem, including changes to the annealing process, the addition of elements like copper and nickel, and the inclusion of conformal coatings. Traditionally, lead has been added to slow down whisker growth in tin-based solders.

Gold plating

Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver, by chemical or electrochemical plating. This article covers plating methods used in the modern electronics industry; for more traditional methods, often used for much larger objects, see gilding.

A solid solution describes a family of materials which have a range of compositions and a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to describe the intimate mixing of components at the atomic level and distinguishes these homogeneous materials from physical mixtures of components.

White tin is refined, metallic tin.

Dip soldering

Dip soldering is a small-scale soldering process by which electronic components are soldered to a printed circuit board (PCB) to form an electronic assembly. The solder wets to the exposed metallic areas of the board, creating a reliable mechanical and electrical connection.

The Occam process is a solder-free, Restriction of Hazardous Substances Directive (RoHS)-compliant method for use in the manufacturing of electronic circuit boards developed by Verdant Electronics. It combines the usual two steps of the construction of printed circuit boards (PCBs) followed by the population process of placing various leaded and non-leaded electronic components into one process.

Soldering Process of joining metal pieces with heated filler metal

Soldering is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involve melting the work pieces. In brazing, the work piece metal also does not melt, but the filler metal is one that melts at a higher temperature than in soldering. In the past, nearly all solders contained lead, but environmental and health concerns have increasingly dictated use of lead-free alloys for electronics and plumbing purposes.

Failure of electronic components Ways electronic components fail and prevention measures

Electronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.

Tin-silver-copper, is a lead-free (Pb-free) alloy commonly used for electronic solder. It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. Lead-free solder is gaining much attention as the environmental effects of lead in industrial products is recognized, and as a result of Europe's RoHS legislation to remove lead and other hazardous materials from electronics. Japanese electronics companies have also looked at Pb-free solder for its industrial advantages.

Materials for use in vacuum

Materials for use in vacuum are materials that show very low rates of outgassing in vacuum and, where applicable, are tolerant to bake-out temperatures. The requirements grow increasingly stringent with the desired degree of vacuum to be achieved in the vacuum chamber. The materials can produce gas by several mechanisms. Molecules of gases and water can be adsorbed on the material surface. Materials may sublimate in vacuum. Or the gases can be released from porous materials or from cracks and crevices. Traces of lubricants, residues from machining, can be present on the surfaces. A specific risk is outgassing of solvents absorbed in plastics after cleaning.

Copper conductor Electrical wire or other conductor made of copper

Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.

Solder fatigue is the mechanical degradation of solder due to deformation under cyclic loading. This can often occur at stress levels below the yield stress of solder as a result of repeated temperature fluctuations, mechanical vibrations, or mechanical loads. Techniques to evaluate solder fatigue behavior include finite element analysis and semi-analytical closed-form equations.


  1. Burns, Neil Douglas (Oct 2009), "A Tin Pest Failure", Journal of Failure Analysis and Prevention, 9 (5): 461–465, doi:10.1007/s11668-009-9280-8, ISSN   1864-1245, S2CID   136953708 , (Print) ISSN   1547-7029
  2. Tin Pest ControlNational Physical Laboratory, www.npl.co.uk Archived 2020-05-05 at the Wayback Machine
  3. Janey Levy Tin, The Rosen Publishing Group, 2009, ISBN   1-4358-5073-4, page 20
  4. 1 2 Adams, Cecil (May 2, 2008). "Did tin disease contribute to Napoleon's defeat in Russia?". The Straight Dope . Retrieved 17 August 2010.
  5. 1 2 3 Öhrström, Lars (2013). The Last Alchemist in Paris. Oxford, UK: Oxford University Press. ISBN   978-0-19-966109-1.
  6. Emsley, John (1 October 2011) [2001]. Nature's Building Blocks: an A-Z Guide to the Elements (New ed.). New York, United States: Oxford University Press. p. 552. ISBN   978-0-19-960563-7. Only officers had metal buttons, and those were made of brass.
  7. Fritsche, Carl (1869). "Ueber eigenthumlich modificirtes Zinn". Berichte der Deutschen Chemischen Gesellschaft. 2: 112–113. doi:10.1002/cber.18690020156.
  8. Zamoyski, Adam (2004). Napoleons Fatal March on Moscow. New York, NY: Harper Perennial.
  9. Sampson, Michael J. (2010-06-22). Lead-free Electronics; Impact for Space Electronics (PDF). 1st NASA Electronic Parts and Packaging (NEPP) Program Electronic Technology Workshop, NASA GSFC, Greenbelt, MD, USA.: NASA.{{cite conference}}: CS1 maint: location (link)
External video
Nuvola apps kaboodle.svg tin pest, transformation of beta tin into alpha modification (grey tin) on YouTube
Time lapse video of tin pest on an ingot