Tin Whiskers growing on a MATTE tin-plated copper leadframe commonly used in the manufacture of 28 pin small outline integrated circuit (SOIC) leadframe after 3 years of ambient storage.

Solder dip vs. plated whisker growth.

Metal whiskering is a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Metallurgy is a domain of Materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their In Mineralogy, shape and size give rise to descriptive terms applied to the typical appearance or habit of Crystals The many terms used by mineralogists The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across The effect is primarily seen on elemental metals but also occurs with alloys. The concept of electrical elements is used in the analysis of Electrical networks. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has

The mechanism behind metal whisker growth is not well understood, but seems to be encouraged by compressive mechanical stresses including:

• residual stresses caused by electroplating;
• mechanically induced stresses;
• stresses induced by diffusion of different metals; and
• thermally induced stresses. Stress is a measure of the average amount of Force exerted per unit Area. Residual stresses are stresses that remain after the original cause of the stresses (external forces heat gradient has been removed Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object Diffusion is the net movement of particles (typically molecules from an area of high concentration to an area of low concentration by uncoordinated random movement

Metal whiskers differ from metallic dendrites in several respects; dendrites are fern-shaped, and grow across the surface of the metal, while metal whiskers are hair like and project at a right-angle to the surface. A crystal dendrite is a crystal that develops with a typical multi-branching tree-like form A fern is any one of a group of about 20000 Species of Plants classified in the phylum or division Pteridophyta, also known as Filicophyta Dendrite growth requires moisture capable of dissolving the metal into a solution of metal ions which are then redistributed by electromigration in the presence of an electromagnetic field. While the precise mechanism for whisker formation remains unknown, it is known that whisker formation does not require either dissolution of the metal or the presence of an electromagnetic field.

Whiskers can cause short circuits and arcing in electrical equipment. Short Circuit is a 1986 comedy Science fiction film starring Ally Sheedy and Steve Guttenberg and directed by An electric arc is an Electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive The phenomenon was discovered by telephone companies in the late 1940s and it was later found that the addition of lead to tin solder provided mitigation. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly A solder is a fusible metal Alloy with a melting point or melting range of 90 to 450 ° C (200 to 840 ° F) used in a process called Restriction of Hazardous Substances (RoHS) in electronic equipment is driving the development of replacement alloys for pure tin and tin/lead alloys that resist whisker growth. The Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment 2002/95/EC ( / commonly referred to as the Restriction of Hazardous Tin is a Chemical element with the symbol Sn (stannum and Atomic number 50 An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Others have focused on the development of oxygen-barrier coatings to prevent whisker formation. ^{citation needed}

Zinc whiskers have been responsible for increased system failure rates in computer server rooms. Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 A computer is a Machine that manipulates data according to a list of instructions. A server room is a room that houses mainly Computer servers In Information technology circles the term is generally used for smaller arrangements ^[1] Zinc whiskers grow from galvanized (electroplated) metal surfaces at a rate of up to 1 mm per year with a diameter of a few micrometres. Whiskers can form on the underside of zinc electroplated floor tiles on raised floors due to stresses applied when walking over them; and these whiskers can then become airborne within the floor plenum when the tiles are disturbed, usually during maintenance. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object A tile is a manufactured piece of hard-wearing material such as Ceramic, stone, metal or even Glass. Whiskers can be small enough to pass through air filters and can settle inside equipment, resulting in short circuits and system failure. Short Circuit is a 1986 comedy Science fiction film starring Ally Sheedy and Steve Guttenberg and directed by

Tin whiskers don't have to be airborne to damage equipment, as they are typically already growing in an environment where they can produce short circuits. Tin is a Chemical element with the symbol Sn (stannum and Atomic number 50 Short Circuit is a 1986 comedy Science fiction film starring Ally Sheedy and Steve Guttenberg and directed by Tin whiskers caused the failure of the Galaxy IV satellite in 1998^[2]. Galaxy IV was a model HS-601 satellite built by Hughes Space and Communications Company (HSC This article is about artificial satellites For natural satellites also known as moons see Natural satellite. At frequencies above 6 GHz or in fast digital circuits, tin whiskers can act like miniature antennas, affecting the circuit impedance and causing reflections. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into The characteristic impedance or surge impedance of a uniform Transmission line, usually written Z_0 is the ratio of the amplitudes of a single In computer disk drives they can break off and cause head crashes or bearing failures. Tin whiskers often cause failures in relays, and have been found upon examination of failed relays in nuclear power facilities. A relay is an electrical Switch that opens and closes under the control of another Electrical circuit. Nuclear power is any Nuclear technology designed to extract usable Energy from atomic nuclei via controlled Nuclear reactions ^[3] Pacemakers have been recalled due to tin whiskers ^[4]. Research has also identified a particular failure mode for tin whiskers, where in high power components a short circuiting tin whisker is ionized into a plasma that is capable of conducting hundreds of Amps of current, massively increasing the damaging effect of the short circuit. ^[5]

Silver whiskers are long filaments of elemental silver. Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen They often appear in conjunction with a layer of silver sulfide which forms on the surface of silver electrical contacts operating in an atmosphere rich in hydrogen sulfide and high humidity. Silver sulfide (or Silver sulphide in British English Ag2S is the Sulfide of Silver. Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen An electrical connector is a conductive device for joining Electrical circuits together Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. Such atmospheres can exist in sewage treatment and paper mills. Sewage treatment, or domestic wastewater treatment, is the process of removing Contaminants from Wastewater, both Runoff ( Effluents A paper mill is a Factory devoted to making Paper from wood pulp and other ingredients using a Fourdrinier Machine or similar apparatus

Gold whiskers are thin filaments of elemental gold. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Whiskers over 20 µm in length were observed on gold-plated surfaces and noted in a 2003 NASA internal memorandum. 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 ^[6]

References

See also

• Monocrystalline whisker

External links

• Fortune article "Tin Whiskers: The next Y2k problem?"
• Teverovsky Gold Whiskers
• Zinc whiskers tangle data centre ops (Computerworld)
• Zinc whisker awareness by NASA (PDF)
• Nasa photographs of silver whiskers
• Article on silver sulphide formation (PDF)
• Tin Whiskers could threaten Shuttle and International Space Station safety (Space. A monocrystalline whisker is a filament of material that is structured as a single, defect-free Crystal. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program com news article)
• Tackling tin whisker test circuit failures and whisker testing
• Tin Whiskers Imperil Electronics - Associated Press
• iNEMI Tin Whisker Activities
• A History of Tin Whisker Theory: 1946 to 2004, George T. Galyon, IBM eSG Group, SMTAI International conference, September 26-30, 2004 (Chicago, IL).
• Tin Whiskers - calce - University of Maryland