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A solder is a fusible
Fusible alloy

A fusible alloy, usually eutectic alloy is capable of being heat of fusion, as well as being liquefied by heat.Sometimes the term "fusible alloy" is used to describe alloys with a melting point below ....
 metal alloy
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
 with a melting point or melting range of 90 to 450 °C
Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
 (200 to 840 °F
Fahrenheit

Fahrenheit is a temperature scale named after the physicist Daniel Gabriel Fahrenheit , who proposed it in 1724. Today, the scale has largely been replaced by the Celsius scale; it is still in use for non-scientific purposes in the United States and a few other countries such as Belize....
), used in a process called soldering
Soldering

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point....
 where it is melted to join metallic surfaces. It is especially useful in electronics
Electronics

Electronics refers to the flow of charge through nonmetal electrical conductor , whereas electrical refers to the flow of charge through metal electrical conductor....
 and plumbing
Plumbing

Plumbing is the skilled trade of working with pipe , Tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters....
. Alloys that melt between 180 and 190 °C are the most commonly used.

The word solder comes from the Middle English
Middle English

Middle English is the name given by historical linguistics to the diverse forms of the English language spoken between the Norman conquest of England of 1066 and about 1470, when the #Chancery Standard, a form of London-based English, began to become widespread, a process aided by the introduction of the printing press into England by William...
 word soudur, via Old French
Old French

Old French was the Romance languages dialect continuum spoken in territories which span roughly the northern half of modern France and parts of modern Belgium and Switzerland from around 1000 to 1300....
 solduree and soulder, from the Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 solidare, meaning '‘to make solid’'.






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Desoldering
A solder is a fusible
Fusible alloy

A fusible alloy, usually eutectic alloy is capable of being heat of fusion, as well as being liquefied by heat.Sometimes the term "fusible alloy" is used to describe alloys with a melting point below ....
 metal alloy
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
 with a melting point or melting range of 90 to 450 °C
Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
 (200 to 840 °F
Fahrenheit

Fahrenheit is a temperature scale named after the physicist Daniel Gabriel Fahrenheit , who proposed it in 1724. Today, the scale has largely been replaced by the Celsius scale; it is still in use for non-scientific purposes in the United States and a few other countries such as Belize....
), used in a process called soldering
Soldering

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point....
 where it is melted to join metallic surfaces. It is especially useful in electronics
Electronics

Electronics refers to the flow of charge through nonmetal electrical conductor , whereas electrical refers to the flow of charge through metal electrical conductor....
 and plumbing
Plumbing

Plumbing is the skilled trade of working with pipe , Tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters....
. Alloys that melt between 180 and 190 °C are the most commonly used.

The word solder comes from the Middle English
Middle English

Middle English is the name given by historical linguistics to the diverse forms of the English language spoken between the Norman conquest of England of 1066 and about 1470, when the #Chancery Standard, a form of London-based English, began to become widespread, a process aided by the introduction of the printing press into England by William...
 word soudur, via Old French
Old French

Old French was the Romance languages dialect continuum spoken in territories which span roughly the northern half of modern France and parts of modern Belgium and Switzerland from around 1000 to 1300....
 solduree and soulder, from the Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 solidare, meaning '‘to make solid’'. Solder can contain lead and or flux
Flux (metallurgy)

In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and welding by removing oxidation from the metals to be joined....
 but in many applications solder is now lead free.

Lead solder

Tin
Tin

Tin is a chemical element with the symbol Sn and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide, SnO2....
/lead
Lead

Lead is a main-group Chemical element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal, also considered to be one of the heavy metal ....
 solders are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder’s tensile
Tensile strength

Tensile strength , or is the Stress at which a material breaks or permanently deforms. Tensile strength is an Intensive and extensive properties and, consequently, does not depend on the size of the test specimen....
 and shear strength
Shear strength

Shear strength in engineering is a term used to describe the strength of a material or component against the type of Yield or structural failure where the material or component fails in Shearing ....
s. At the retail level, the two most common alloys are 60/40 Sn
Tin

Tin is a chemical element with the symbol Sn and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide, SnO2....
/Pb
Lead

Lead is a main-group Chemical element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal, also considered to be one of the heavy metal ....
 and 63/37 Sn/Pb used principally in electrical work. The 63/37 ratio is notable in that it is a eutectic
Eutectic point

The melting point of a mixture of two or more solids depends on the relative proportions of its ingredients. A eutectic or eutectic mixture is a mixture at such proportions that the melting point is as low as possible, and that furthermore all the constituents crystallize simultaneously at this temperature from molten liquid solution....
 mixture, which means:
  1. It has the lowest melting point (183 °C or 361.4 °F) of all the tin/lead alloys; and
  2. The melting point is truly a point — not a range


At a eutectic composition, the liquid solder solidifies as a eutectic, which consists of fine grains of nearly pure lead and nearly pure tin phases, but in no way is it an intermetallic, since there are no tin/lead intermetallics, as can be seen from a tin/lead equilibrium diagram.

In plumbing, a higher proportion of lead was used. This had the advantage of making the alloy solidify more slowly, so that it could be wiped over the joint to ensure watertightness. Although lead water pipes were displaced by copper when the significance of lead poisoning
Lead poisoning

Lead poisoning is a medical condition caused by increased levels of the metal lead in the blood. Lead may cause irreversible neurological damage as well as renal disease, cardiovascular effects, and human reproduction toxicity....
 began to be fully appreciated, lead solder was still used until the 1980s because it was thought that the amount of lead that could leach into water from the solder was negligible. Since even small amounts of lead have been found detrimental to health, lead in plumbing solder was replaced by copper
Copper

Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
 or antimony
Antimony

Antimony is a chemical element with the symbol Sb and atomic number 51. A metalloid, antimony has four allotropy forms. The stable form of antimony is a blue-white metalloid....
, with silver
Silver

Silver is a 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....
 often added, and the proportion of tin was increased (see Lead-free solder.)

Pure lead solder is known to go into solution causing big problems. Lead tin solder, however, is very stable and does not go into solution, even in land fill sites.

Hard solder

As used for brazing
Brazing

Brazing is a joining process whereby a filler metal or alloy is heated to melting temperature above ?or, by the traditional definition in the United States, above ?and distributed between two or more close-fitting parts by capillary action....
, is generally a copper/zinc
Zinc

Zinc is a metallic chemical element with the symbol Zn and atomic number 30. It is a first-row transition metal of the group 12 element of the periodic table....
 or copper/silver alloy, and melts at higher temperatures.

In silversmithing or jewelry making, special hard solders are used that will pass assay
Assay

An assay is a procedure where a property or concentration of an analyte is measured.In the field of molecular biology assays include: antigen capture assay; bioassay; competitive protein binding assay; immunoassay, microbiological assay, stem cell assay, MTT assay and others....
. They contain a high proportion of the metal being soldered and lead is not used in these alloys. These solders also come in a variety of hardnesses, known as 'enamelling', 'hard', 'medium' and 'easy'. Enamelling
Vitreous enamel

In a discussion of material science, enamel is the colorful result of fusing powdered glass to a substrate by firing, usually between 750 and 850 degrees Celsius....
  solder has a high melting point, close to that of the material itself, to prevent the joint desoldering
Desoldering

In electronics, desoldering is the removal of solder and components from a electrical network for troubleshooting, repair purposes and to salvage components....
 during firing in the enamelling process. The remaining solder types are used in decreasing order of hardness during the process of making an item, to prevent a previously soldered seam or joint desoldering while soldering a new joint. Easy solder is also often used for repair work for the same reason. Flux
Flux (metallurgy)

In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and welding by removing oxidation from the metals to be joined....
 or rouge is also used to prevent joints desoldering.

Silver solder is also used in manufacturing, when there is a need to join metal parts that cannot be welded
Welding

Welding is a fabrication or sculpture process that joins materials, usually metals or thermoplastics, by causing coalescence . This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself,...
. The alloys used for these purposes contain a high proportion of silver (up to 40%), and may also contain toxic cadmium
Cadmium

Cadmium is a chemical element with the symbol Cd and atomic number 48. A relatively abundant , soft, bluish-white, transition metal, cadmium is known to cause cancer and occurs with zinc ores....
.

Flux core solder

Ersin Multicore Solder Tube
Solder often comes pre-mixed with, or is used with, flux
Flux (metallurgy)

In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and welding by removing oxidation from the metals to be joined....
, a reducing agent designed to help remove impurities (specifically oxidised metals) from the points of contact to improve the electrical connection. For convenience, solder is often manufactured as a hollow tube and filled with flux. Most cold solder is soft enough to be rolled and packaged as a coil, making for a convenient and compact solder/flux package. The two principal types of flux are acid flux, used for metal mending, and rosin
Rosin

Rosin, formerly called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly Pinophyta, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components....
 flux, used in electronics, where the corrosiveness of the vapours that arise when acid flux is heated could damage components. Due to concerns over atmospheric pollution and hazardous waste disposal, the electronics industry has been gradually shifting from rosin flux to water-soluble flux, which can be removed with deionised water and detergent, instead of hydrocarbon solvents.

Lead-free solder

On July 1 2006 the European Union
European Union

The European Union is an economic and political union of 27 European Union member state, located primarily in Europe. It was established by the Treaty of Maastricht on 1 November 1993 upon the foundations of the pre-existing European Economic Community....
 Waste Electrical and Electronic Equipment Directive
Waste Electrical and Electronic Equipment Directive

File:WEEE_symbol_vectors.svgThe Waste Electrical and Electronic Equipment Directive is the European Community directive 2002/96/EC on electronic waste which, together with the Restriction of Hazardous Substances Directive 2002/95/EC, became European Law in February 2003, setting collection, recycling and recovery targets for all types o...
 (WEEE) and 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....
 (RoHS) came into effect prohibiting the intentional addition of lead to most consumer electronics produced in the EU. California recently adopted a RoHS law and China has a version as well. Manufacturers in the U.S. may receive tax benefits by reducing the use of lead-based solder. Lead-free solders in commercial use may contain tin
Tin

Tin is a chemical element with the symbol Sn and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide, SnO2....
, copper
Copper

Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
, silver
Silver

Silver is a 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....
, bismuth
Bismuth

Bismuth is a chemical element that has the symbol Bi and atomic number 83. This heavy, brittle, white crystalline trivalent poor metal has a pink tinge and chemically resembles arsenic and antimony....
, indium
Indium

Indium is a chemical element with chemical symbol In and atomic number 49. This rare, soft, malleable and easily Fusible alloy Post-transition metal is chemically similar to aluminium or gallium but more closely resembles zinc ....
, zinc
Zinc

Zinc is a metallic chemical element with the symbol Zn and atomic number 30. It is a first-row transition metal of the group 12 element of the periodic table....
, antimony
Antimony

Antimony is a chemical element with the symbol Sb and atomic number 51. A metalloid, antimony has four allotropy forms. The stable form of antimony is a blue-white metalloid....
, and traces of other metals. Most lead-free replacements for conventional Sn60/Pb40 and Sn63/Pb37 solder have melting points from 5–20 °C higher, though solders with much lower melting points are available.

Drop-in replacements for silkscreen with solder paste soldering operations are available. Minor modification to the solder pots (e.g. titanium liners and/or impellers) used in wave-soldering operations may be desired to reduce maintenance costs associated with the increased tin-scavenging effects of high tin solders. The properties of lead-free solders are not as thoroughly known and may therefore be considered less reliable in select applications, e.g. High reliability aerospace and life-critical medical. "Tin whiskers
Whisker (metallurgy)

Metal whiskering is a crystalline metallurgy phenomenon involving the spontaneous growth of tiny, crystal habit hairs from a metallic surface....
" were a problem with early electronic solders, and lead was initially added to the alloy in part to eliminate them. These problems are now considered negligible in modern alloys for most applications, however solder containing lead is still used in high reliability military, aerospace-satellite and life-critical medical applications.

  • SnAgCu solders are used by two thirds of Japanese manufacturers for reflow and wave soldering
    Wave soldering

    Wave soldering is a large-scale soldering process by which electronic components are soldered to a printed circuit board to form an electronic assembly....
    , and by about ¾ companies for hand soldering.
    • SnAg3.0Cu0.5, tin with 3% silver and 0.5% copper, has a melting point of 217 to 220 °C and is predominantly used in Japan. It is the JEITA recommended alloy for wave and reflow soldering
      Reflow soldering

      Reflow soldering is a process in which a solder paste is used to temporarily hold the components to their attachment pads, after which the assembly is carefully heated in order to solder the joint....
      , with alternatives SnCu for wave and SnAg and SnZnBi for reflow soldering.
    • SnAg3.5Cu0.7 is another commonly used alloy, with melting point of 217-218 °C.
    • SnAg3.5Cu0.9, with melting point of 217 °C, is determined by NIST to be truly eutectic.
    • SnAg3.8Cu0.7, with melting point 217-218 °C, is preferred by the European IDEALS consortium for reflow soldering.
    • SnAg3.8Cu0.7Sb0.25 is preferred by the European IDEALS consortium for wave soldering.
    • SnAg3.9Cu0.6, with melting point 217-223 °C, is recommended by the US NEMI consortium for reflow soldering.
  • SnCu0.7, with melting point of 227 °C, is a cheap alternative for wave soldering, recommended by the US NEMI consortium.
  • SnZn9, with melting point of 199 °C, is a cheaper alloy but is prone to corrosion
    Corrosion

    Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
     and oxidation.
  • SnZn8Bi3, with melting point of 191-198 °C, is also prone to corrosion
    Corrosion

    Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
     and oxidation due to its zinc content.
  • SnSb5, tin with 5% of antimony
    Antimony

    Antimony is a chemical element with the symbol Sb and atomic number 51. A metalloid, antimony has four allotropy forms. The stable form of antimony is a blue-white metalloid....
    , is the US plumbing
    Plumbing

    Plumbing is the skilled trade of working with pipe , Tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters....
     industry standard. Its melting point is 232-240 °C. It displays good resistance to thermal fatigue and good shear strength
    Shear strength

    Shear strength in engineering is a term used to describe the strength of a material or component against the type of Yield or structural failure where the material or component fails in Shearing ....
    .
  • SnAg2.5Cu0.8Sb0.5 melts at 217-225 °C and is patented by AIM alliance
    AIM alliance

    The AIM alliance was an Business alliance formed in September 1991 between Apple Computer, International Business Machines and Motorola to create a new computing standard based on the PowerPC architecture....
    .
  • SnIn8.0Ag3.5Bi0.5 melts at 197 to 208 °C and is patented by Matsushita
    Matsushita

    Matsushita is a Japan electronics brand .Matsushita is also a family name in Japan....
    /Panasonic
    Panasonic

    Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation Under this brand the company sells Plasma display and LCD display panels, DVD recorders and players, Blu-ray Disc players, camcorders, telephones, vacuum cleaners, microwave ovens, shavers, projectors, digital cameras, batteries, lapto...
    .
  • SnBi57Ag1 melts at 137-139 °C and is patented by Motorola
    Motorola

    Motorola, Inc. is an United States, multinational, Fortune 100, telecommunications company based in Schaumburg, Illinois. It is a manufacturer of wireless telephone handsets, also designing and selling wireless network infrastructure equipment such as cellular transmission base stations and signal amplifiers....
    .
  • SnBi58 melts at 138 °C.
  • SnIn52 melts at 118 °C and is suitable for the cases where low-temperature soldering is needed.


Different elements serve different roles in the solder alloy:
  • Silver
    Silver

    Silver is a 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....
     provides mechanical strength, but has worse ductility
    Ductility

    Ductility is a mechanical property used to describe the extent to which materials can be deformed deformation without fracture.In material science, ductility specifically refers to a material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire....
     than lead. In absence of lead, it improves resistance to fatigue from thermal cycles.
  • Copper
    Copper

    Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
     lowers the melting point, improves resistance to thermal cycle fatigue, and improves wetting
    Wetting

    Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together....
     properties of the molten solder. It also slows down the rate of dissolution of copper from the board and part leads in the liquid solder.
  • Bismuth
    Bismuth

    Bismuth is a chemical element that has the symbol Bi and atomic number 83. This heavy, brittle, white crystalline trivalent poor metal has a pink tinge and chemically resembles arsenic and antimony....
     significantly lowers the melting point and improves wettability. In presence of sufficient lead and tin, bismuth forms crystals of Sn16Pb32Bi52 with melting point of only 95 °C, which diffuses along the grain boundaries and may cause a joint failure at relatively low temperatures. A high-power part pre-tinned with an alloy of lead can therefore desolder under load when soldered with a bismuth-containing solder.
  • Indium
    Indium

    Indium is a chemical element with chemical symbol In and atomic number 49. This rare, soft, malleable and easily Fusible alloy Post-transition metal is chemically similar to aluminium or gallium but more closely resembles zinc ....
     lowers the melting point and improves ductility. In presence of lead it forms a ternary compound that undergoes phase change at 114 °C.
  • Zinc
    Zinc

    Zinc is a metallic chemical element with the symbol Zn and atomic number 30. It is a first-row transition metal of the group 12 element of the periodic table....
     lowers the melting point and is low-cost. However it is highly susceptible to corrosion and oxidation in air, therefore zinc-containing alloys are unsuitable for some purposes, e.g. wave soldering, and zinc-containing solder pastes have shorter shelf life than zinc-free.
  • Antimony
    Antimony

    Antimony is a chemical element with the symbol Sb and atomic number 51. A metalloid, antimony has four allotropy forms. The stable form of antimony is a blue-white metalloid....
     is added to increase strength without affecting wettability.


See also

  • Soldering
    Soldering

    Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point....
  • Solder paste
    Solder paste

    Solder paste is used for connecting the terminations of IC packages with land patterns on the PCB. The paste is applied to the lands by printing the solder using a stencil, while other methods like screening and dispensing are also used....
  • Solder sucker
    Solder sucker

    A solder sucker is a device which is used to remove solder from a printed circuit board , as opposed to a desoldering bulb or solder wick. It is usually a small, spring-loaded device that "sucks", as the name implies, the solder off the previously soldered connection....
  • Solderability
    Solderability

    Solderability defines whether a solder can perform as intended in-service under normal fabrication methods or processes. The electronic industry has a consensus specification which provides guidelines for classifying, testing, marking, and packaging accepted solder compositions....
  • Soldering gun
    Soldering gun

    A soldering gun is a tool for soldering metals using lead-tin-based solder to achieve a highly conductive contact. The tool uses a pistol shape, and has a trigger style switch so it can be easily operated with one hand....
  • Soldering iron
    Soldering iron

    A soldering iron is a "device" for applying heat to melt solder for attaching two metal parts.A soldering iron is composed of a heated metal tip and an insulated handle....
  • Welding
    Welding

    Welding is a fabrication or sculpture process that joins materials, usually metals or thermoplastics, by causing coalescence . This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself,...
  • Brazing
    Brazing

    Brazing is a joining process whereby a filler metal or alloy is heated to melting temperature above ?or, by the traditional definition in the United States, above ?and distributed between two or more close-fitting parts by capillary action....


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