Solder alloys

Solder is a metallic material that is used to connect metal workpieces. The choice of specific solder alloys depends on their melting point, chemical reactivity, mechanical properties, toxicity, and other properties. Hence a wide range of solder alloys exist, and only major ones are listed below. Since early 2000s the use of lead in solder alloys is discouraged by several governmental guidelines in the European Union, Japan and other countries,^[1] such as Restriction of Hazardous Substances Directive and Waste Electrical and Electronic Equipment Directive.

Soldering copper pipes using a propane torch and a lead-free solder

Solder alloys

Composition	Melting point (°C)		Non-toxic	Eutectic	Comments
	Solidus	Liquidus
Bi100	271		Yes	Pure	Used as a non-superconducting solder in low-temperature physics. Does not wet metals well, forms a mechanically weak joint.[2]
In66.7Bi33.3	72.7
In61.7Bi30.8Cd7.5	62[3]		Cd	Yes
Bi56Sn30In14	79	91		Yes	ChipQuik desoldering alloy, lead-free[4]
In51.0Bi32.5Sn16.5	60.5		Yes	Yes	Field's metal
Bi50.0Pb25.0Sn12.5Cd12.5	71		Cd, Pb	Near	Wood's metal, mostly used for casting.
Bi50Pb26.7Sn13.3Cd10	70		Cd, Pb	Yes	Cerrobend. Used in low-temperature physics as a solder.[2]
Bi49.5Pb27.3Sn13.1Cd10.1	70.9		Cd, Pb	Near	Lipowitz Metal
Bi50.5Pb27.8Sn12.4Cd9.3	70	73[5]	Cd, Pb	No
Bi44.7Pb22.6In19.1Cd5.3Sn8.3	47		Cd, Pb	Yes	Cerrolow 117. Used as a solder in low-temperature physics.[2]
Bi49Pb18Sn12In21	58		Pb	Yes	Cerrolow 136. Slightly expands on cooling, later shows slight shrinkage in couple hours afterwards. Used as a solder in low-temperature physics.[2] Also the ChipQuik desoldering alloy.[6]
Bi49Pb18Sn15In18	58	69[7]	Pb	No
Bi48Pb25.4Sn12.8Cd9.6In4	61	65[8]	Cd, Pb	No
Bi47.5Pb25.4Sn12.6Cd9.5In5	57	65[9]	Cd, Pb	No
Bi58Pb42	124	126[10]	Pb
Bi58Sn42	138[11][12]		Yes	Yes	Bi58. Reasonable shear strength and fatigue properties. Combination with lead-tin solder may dramatically lower melting point and lead to joint failure.[13] Low-temperature eutectic solder with high strength.[12] Particularly strong, very brittle.[11] Used extensively in through-hole technology assemblies in IBM mainframe computers where low soldering temperature was required. Can be used as a coating of copper particles to facilitate their bonding under pressure/heat and creating a conductive metallurgical joint.[14] Sensitive to shear rate. Good for electronics. Used in thermoelectric applications. Good thermal fatigue performance.[15] Established history of use. Expands slightly on casting, then undergoes very low further shrinkage or expansion, unlike many other low-temperature alloys which continue changing dimensions for some hours after solidification.[2] https://himikatus.ru/art/phase-diagr1/Bi-Sn.php confirms eutectic at 139 C
Bi52Pb32Sn16	96		Pb	yes?	Bi52. Good fatigue resistance combined with low melting point. Reasonable shear strength and fatigue properties. Combination with lead-tin solder may dramatically lower melting point and lead to joint failure.[13]
Bi50.0Pb31.2Sn18.8	97		Pb	No	Newton's metal
Bi50Pb28Sn22	109		Pb	No	Rose's metal. It was used to secure cast iron railings and balusters in pockets in stone bases and steps. Does not contract on cooling.
Bi46Sn34Pb20	100	105[16]	Pb	No	Bi46
Sn48Bi32Pb20	140	160[17]	Pb	No	For low-temperature soldering of heat-sensitive parts, and for soldering in the vicinity of already soldered joints without their remelting.
Sn43Pb43Bi14	144	163[11]	Pb	No	Bi14. Good fatigue resistance combined with low melting point. Contains phases of tin and lead-bismuth.[13] Useful for step soldering.
Sn46Pb46Bi8	120	167[16]	Pb	No	Bi8
Sn89Zn8Bi3	191	198	Yes		Prone to corrosion and oxidation due to its zinc content. On copper surfaces forms a brittle Cu-Zn intermetallic layer, reducing the fatigue resistance of the joint; nickel plating of copper inhibits this.[14]
Sn86.5Zn5.5In4.5Bi3.5	174	186[18]	Yes	No	Lead-free. Corrosion concerns and high drossing due to zinc content.
Bi57Sn42Ag1	137 139	139 140[19]	Yes		Addition of silver improves mechanical strength. Established history of use. Good thermal fatigue performance. Patented by Motorola.
Sn91.8Bi4.8Ag3.4	211	213[20]	Yes	No	Do not use on lead-containing metallizations.[21]
Sn88In8.0Ag3.5Bi0.5	197	208	Yes		Patented by Matsushita/Panasonic. [citation needed]
Sn99.3Cu0.7Ni?Bi?	227[22]			Yes	K100LD, a lead-free silver-free nickel-stabilized alloy, with low dissolving (LD) of copper. Proprietary to Kester. Similar to Sn99Cu1. The nickel content lowers copper erosion and promotes shiny solder fillet. Bismuth acts in synergy with nickel to further reduce copper dissolution and reduces surface tension. Performance similar to SAC alloys at lower cost. K100LDa has 0.2% copper, used to refill wave soldering pots to counteract copper buildup. Lower than optimal nickel content to avoid patents?[23]
In74Cd26	123[24]		Cd	Yes
Pb92Cd8	310?		Cd, Pb	?	For soldering aluminium.[25][26]
Cd70Sn30	140	160[16]	Cd	No	Cd70, thermal-free solder. Produces low thermal EMF joints in copper, does not form parasitic thermocouples. Used in low-temperature physics.[2]
Sn40Pb42Cd18	145		Cd, Pb		Low melting temperature allows repairing pewter and zinc objects, including die-cast toys.
Sn50Pb32Cd18	145[16]		Cd, Pb		Cd18
Cd82.5Zn17.5	265[27]		Cd	Yes	Medium temperature alloy that provide strong, corrosion-resistant joints on most metals.[27] Also for soldering aluminium and die-cast zinc alloys.[28] Used in cryogenic physics for attaching electrical potential leads to specimens of metals, as this alloy does not become superconductive at liquid helium temperatures.[2]
Cd70Zn30	265	300[27]	Cd	No	Medium temperature alloy that provide strong, corrosion-resistant joints on most metals. Works especially well on aluminium-to-aluminium and aluminium-to-copper joints, with excellent corrosion resistance and superior strength in high vibration and high stress applications in electronics, lighting and electrical products.[27]
Cd60Zn40	265	316[27]	Cd	No	Medium temperature alloy that provide strong, corrosion-resistant joints on most metals. Works especially well on aluminium-to-aluminium and aluminium-to-copper joints, with excellent corrosion resistance and superior strength in high vibration and high stress applications in electronics, lighting and electrical products.[27]
Zn60Cd40	265	335	Cd		For soldering aluminium. Very good wetting.[29]
Zn90Cd10	265	399	Cd		For soldering aluminium. Good wetting.[29]
Sn40Zn27Cd33	176	260[30]	Cd	No	KappRad[30] Developed specifically to join and repair aluminium and aluminium/copper radiators and heat exchangers. A lower melting point makes delicate repair work easier.[30]
Cd95Ag5	338	393[31]	Cd	No	KappTec General purpose solder that will join all solderable metals except aluminium. High temperature, high strength solder. It is used in applications where alloys melting higher than soft solders are required, but the cost and strength of silver-brazing alloys is not necessary.[31]
Cd78Zn17Ag5	249	316[32]	Cd	No	KappTecZ High temperature, high strength solder that may be used on most metals, but works extremely well on aluminium, copper and stainless steel. It has a high tolerance to vibration and stress, and good elongation for use on dissimilar metals. Above its liquidus of 600 °F, this solder is extremely fluid and will penetrate the closest joints.[32]
Sn51.2Pb30.6Cd18.2	145[33]		Cd, Pb	Yes	General-purpose. Maintains creep strength well. Unsuitable for gold.
In70Sn15Pb9.6Cd5.4	125[34]		Cd, Pb
In100	157		Yes	Pure	In99. Used for die attachment of some chips. More suitable for soldering gold, dissolution rate of gold is 17 times slower than in tin-based solders and up to 20% of gold can be tolerated without significant embrittlement. Good performance at cryogenic temperatures.[35] Wets many surfaces incl. quartz, glass, and many ceramics. Deforms indefinitely under load. Does not become brittle even at low temperatures. Used as a solder in low-temperature physics, will bond to aluminium. Can be used for soldering to thin metal films or glass with an ultrasonic soldering iron.[2]
In75Pb25	156	165[12]	Pb	No	Less gold dissolution and more ductile than lead-tin alloys. Used for die attachment, general circuit assembly and packaging closures.[12]
In70Pb30	160 165	174[11] 175[16][36]	Pb	No	In70. Suitable for gold, low gold-leaching. Good thermal fatigue properties.
In60Pb40	174 173	185[11] 181[16]	Pb	No	In60. Low gold-leaching. Good thermal fatigue properties.
In50Pb50	180 178	209[12] 210[16]	Pb	No	In50. Only one phase. Resoldering with lead-tin solder forms indium-tin and indium-lead phases and leads to formation of cracks between the phases, joint weakening and failure.[13] On gold surfaces gold-indium intermetallics tend to be formed, and the joint then fails in the gold-depleted zone and the gold-rich intermetallic.[37] Less gold dissolution and more ductile than lead-tin alloys.[12] Good thermal fatigue properties.
Pb60In40	195	225[16]	Pb	No	In40. Low gold-leaching. Good thermal fatigue properties.
Pb70In30	245	260[16]	Pb	No	In30
Pb75In25	250 240	264[12] 260[38]	Pb	No	In25. Low gold-leaching. Good thermal fatigue properties. Used for die attachment of e.g. GaAs dies.[37] Used also for general circuit assembly and packaging closures. Less dissolution of gold and more ductile than tin-lead alloy.[12]
Pb81In19	270 260	280[16] 275[39]	Pb	No	In19. Low gold-leaching. Good thermal fatigue properties.
In60Sn40	113	122[11]	Yes	No
In52Sn48	118		Yes	Yes	In52. Suitable for the cases where low-temperature soldering is needed. Can be used for glass sealing.[14] Sharp melting point. Good wettability of glass, quartz, and many ceramics. Good low-temperature malleability, can compensate for different thermal expansion coefficients of joined materials.
In50Sn50	118	125[40]	Yes	No	Cerroseal 35. Fairly well wets glass, quartz and many ceramics. Malleable, can compensate some thermal expansion differences. Low vapor pressure. Used in low temperature physics as a glass-wetting solder.[2]
Sn52In48	118	131[11]	Yes	No	very low tensile strength
Sn58In42	118	145[41]	Yes	No
Sn37.5Pb37.5In26	134	181[16]	Pb	No	In26
Sn37.5Pb37.5In25	134	181[12]	Pb	No	Good wettability. Not recommended for gold.[12]
Sn54Pb26In20	130 140	154[16] 152[42]	Pb	No	In20
Sn70Pb18In12	162[11]		Pb	Yes	General purpose. Good physical properties.
	154	167[43]
In80Pb15Ag5	142 149	149[16] 154[44]	Pb	No	In80. Compatible with gold, minimum gold-leaching. Resistant to thermal fatigue. Can be used in step soldering.
Pb92.5In5Ag2.5	300	310[11]	Pb	No	UNS L51510. Minimal leaching of gold, good thermal fatigue properties. Reducing atmosphere frequently used..
Pb90In5Ag5	290	310[11]	Pb	No
Pb92.5In5Au2.5	300	310[16]	Pb	No	In5
Sn83.6Zn7.6In8.8	181	187[45]	Yes	No	High dross due to zinc.[46]
Sn77.2In20Ag2.8	175	187[47]	Yes	No	Similar mechanical properties with Sn63Pb37, Sn62Pb36Ag2 and Sn60Pb40, suitable lead-free replacement. Contains eutectic Sn-In phase with melting point at 118 °C, avoid use above 100 °C.
Sn86.9In10Ag3.1	204	205[48]	Yes		Potential use in flip-chip assembly, no issues with tin-indium eutectic phase.
In97Ag3	143[49]		Yes	Yes	Wettability and low-temperature malleability of indium, strength improved by addition of silver. Particularly good for cryogenic applications. Used for packaging of photonic devices.
In90Ag10	143	237[50]	Yes	No	Nearly as wettable and low-temperature malleable as indium. Large plastic range. Can solder silver, fired glass and ceramics.
Au82In18	451	485[16]	Yes	No	Au82. High-temperature, extremely hard, very stiff.
Pb90Sn10	268 275	302[11] 302[16]	Pb	No	Sn10, UNS L54520, ASTM10B. Balls for CBGA components, replaced by Sn95.5Ag3.9Cu0.6.[51] Low cost and good bonding properties. Rapidly dissolves gold and silver, not recommended for those.[12] Used for fabrication of car radiators and fuel tanks, for coating and bonding of metals for moderate service temperatures. Body solder.[52] Has low thermal EMF, can be used as an alternative to Cd70 where parasitic thermocouple voltage has to be avoided.[53]
Pb88Sn12	254	296[52]	Pb	No	Used for fabrication of car radiators and fuel tanks, for coating and bonding of metals for moderate service temperatures. Body solder.
Pb85Sn15	227	288[52]	Pb	No	Used for coating tubes and sheets and fabrication of car radiators. Body solder.
Pb80Sn20	183	280[16]	Pb	No	Sn20, UNS L54711. Used for coating radiator tubes for joining fins.[52]
Pb75Sn25	183	266[11]	Pb	No	Crude solder for construction plumbing works, flame-melted. Used for soldering car engine radiators. Used for machine, dip and hand soldering of plumbing fixtures and fittings. Superior body solder.[52]
Pb70Sn30	185 183	255 257[16]	Pb	No	Sn30, UNS L54280, crude solder for construction plumbing works, flame-melted, good for machine and torch soldering.[54] Used for soldering car engine radiators. Used for machine, dip and hand soldering of plumbing fixtures and fittings. Superior body solder.[52]
Pb68Sn32	253		Pb	No	"Plumber solder", for construction plumbing works[28]
Pb67Sn33	187	230	Pb	No	PM 33, crude solder for construction plumbing works, flame-melted, temperature depends on additives
Pb65Sn35	183	250[16]	Pb	No	Sn35. Used as a cheaper alternative of Pb60Sn40 for wiping and sweating joints.[52]
Pb60Sn40	183	238[11] 247[16]	Pb	No	Sn40, UNS L54915. For soldering of brass and car radiators.[54] For bulk soldering, and where wider melting point range is desired. For joining cables. For wiping and joining lead pipes. For repairs of radiators and electrical systems.[52]
Pb55Sn45	183	227[52]	Pb	No	For soldering radiator cores, roof seams, and for decorative joints.
Sn50Pb50	183	216[11] 212[16]	Pb	No	Sn50, UNS L55030. "Ordinary solder", for soldering of brass, electricity meters, gas meters, formerly also tin cans. General purpose, for standard tinning and sheetmetal work. Becomes brittle below ?150 °C.[55][28] Low cost and good bonding properties. Rapidly dissolves gold and silver, not recommended for those.[12] For wiping and assembling plumbing joints for non-potable water.[52]
Sn60Pb40	183	190[11] 188[16]	Pb	Near	Sn60, ASTM60A, ASTM60B. Common in electronics, most popular leaded alloy for dipping. Low cost and good bonding properties. Used in both SMT and through-hole electronics. Rapidly dissolves gold and silver, not recommended for those.[12] Slightly cheaper than Sn63Pb37, often used instead for cost reasons as the melting point difference is insignificant in practice. On slow cooling gives slightly duller joints than Sn63Pb37.[56]
Sn62Pb38	183		Pb	Near	"Tinman's solder", used for tinplate fabrication work.[28]
Sn63Pb37	183[57]		Pb	Yes	Sn63, ASTM63A, ASTM63B. Common in electronics; exceptional tinning and wetting properties, also good for stainless steel. One of the most common solders. Low cost and good bonding properties. Used in both SMT and through-hole electronics. Rapidly dissolves gold and silver, not recommended for those.[12] Sn60Pb40 is slightly cheaper and is often used instead for cost reasons, as the melting point difference is insignificant in practice. On slow cooling gives slightly brighter joints than Sn60Pb40.[56]
Sn70Pb30	183	193[11]	Pb	No	Sn70
Sn75Pb25	183	238[58]	Pb	No
Sn90Pb10	183	213[16]	Pb	No	formerly used for joints in food industry
Sn95Pb5	238		Pb	No	plumbing and heating
Pb63Sn34Zn3	170	256	Pb	No	Poor wetting of aluminium. Poor corrosion rating.[59]
Sn30Pb50Zn20	177	288[60]	Pb	No	Kapp GalvRepair Economical solder for repairing & joining most metals including aluminium and cast iron. Has been used for cast iron and galvanized surface repair.[60]
Sn33Pb40Zn28	230	275[60]	Pb	No	Economical solder for repairing & joining most metals including aluminium and cast iron. Has been used for cast iron and galvanized surface repair.[60]
Pb97.5Ag1.5Sn1	309[11]		Pb	Yes	Ag1.5, ASTM1.5S. High melting point, used for commutators, armatures, and initial solder joints where remelting when working on nearby joints is undesirable.[54] Silver content reduces solubility of silver coatings in molten solder. Not recommended for gold.[12] Standard PbAgSn eutectic solder, wide use in semiconductor assembly. Reducing protective atmosphere (e.g. 12% hydrogen) often used. High creep resistance, for use at both elevated and cryogenic temperatures.
Pb96Sn2Ag2	252	295[16]	Pb		Pb96
Pb95.5Sn2Ag2.5	299	304[11]	Pb	No
Pb93.5Sn5Ag1.5	296 305	301[11] 306[16]	Pb	No	Pb94, HMP alloy, HMP. Service temperatures up to 255 °C. Useful for step soldering. Also can be used for extremely low temperatures as it remains ductile down to −200 °C, while solders with more than 20% tin become brittle below −70 °C. Higher strength and better wetting than Pb95Sn5.[56]
Pb92.5Sn5Ag2.5	287 299	296[11] 304[16]	Pb	No	Pb93.
Pb92Sn5.5Ag2.5	286	301[17]	Pb	No	For higher-temperature applications.
Pb90Sn5Ag5	292[11]		Pb	Yes
Pb88Sn10Ag2	268 267	290[11] 299[61]	Pb	No	Sn10, Pb88. Silver content reduces solubility of silver coatings in the solder. Not recommended for gold.[12] Forms a eutectic phase, not recommended for operation above 120 °C.
Pb80Sn18Ag2	252	260[16]	Pb	No	Used for soldering iron and steel[28]
Pb54Sn45Ag1	177	210	Pb		exceptional strength, silver gives it a bright long-lasting finish; ideal for stainless steel[54]
Sn56Pb39Ag5			Pb		[55]
Sn62.5Pb36Ag2.5	179[11]		Pb	Yes
Sn62Pb36Ag2	179[11]		Pb	Yes	Sn62. Common in electronics. The strongest tin-lead solder. Appearance identical to Sn60Pb40 or Sn63Pb37. Crystals of Ag3Sn may be seen growing from the solder. Extended heat treatment leads to formation of crystals of binary alloys. Silver content decreases solubility of silver, making the alloy suitable for soldering silver-metallized surfaces, e.g. SMD capacitors and other silver-metallized ceramics.[55][56][13] Not recommended for gold.[12] General-purpose.
Sn61Pb36Ag3	205[62]		Pb		[55] Often referred as POS61 (Russian: ПОС61) in Russia (silver may not be necessarily present).
Sn97.5Pb1Ag1.5	305		Pb	Yes	Important for hybrid circuits assembly.[55]
Sn50Pb48.5Cu1.5	183	215[63]	Pb	No	Savbit, Savbit 1, Sav1. Minimizes dissolution of copper. Originally designed to reduce erosion of the soldering iron tips. About 100 times slower erosion of copper than ordinary tin/lead alloys. Suitable for soldering thin copper platings and very thin copper wires.[56]
Sn60Pb39Cu1			Pb	No
Sn60Pb38Cu2	183	190[16][17]	Pb		Cu2. Copper content increases hardness of the alloy and inhibits dissolution of soldering iron tips and part leads in molten solder.
Sn62Pb37Cu1	183[17]		Pb	Yes	Similar to Sn63Pb37. Copper content increases hardness of the alloy and inhibits dissolution of soldering iron tips and part leads in molten solder.
Sn63Pb37P0.0015-0.04	183[64]		Pb	Yes	Sn63PbP. A special alloy for HASL machines. Addition of phosphorus reduces oxidation. Unsuitable for wave soldering as it may form metal foam.
Pb80Sn12Sb8			Pb	No	Used for soldering iron and steel[28]
Pb80Sb15Sn5	300		Pb		White Metal Capping. Used for locking mineshaft winding ropes into their tapered end sockets or 'capels'.[65]
Pb79Sn20Sb1	184	270	Pb	No	Sb1
Pb68Sn30Sb2	185	243[16]	Pb	No	Pb68
Pb63Sn35Sb2	185	243[16]	Pb	No	Sb2
Pb55Sn43.5Sb1.5			Pb	No	General purpose solder. Antimony content improves mechanical properties but causes brittleness when soldering cadmium, zinc, or galvanized metals.[28]
Pb97.5Ag2.5	303[11] 304[16]		Pb	Yes	Ag2.5, UNS L50132. Used during World War II to conserve tin. Poor corrosion resistance; joints suffered corrosion in both atmospheric and underground conditions, all had to be replaced with Sn-Pb alloy joints.[59] Torch solder.
	304	579[66]
Pb96Ag4	305		Pb		high-temperature joints[54]
Pb95Ag5	305	364[67]	Pb	No
Pb94.5Ag5.5	305 304	364[16] 343[68]	Pb	No	Ag5.5, UNS L50180
Sn	232		Yes	Pure	Sn99. Good strength, non-dulling. Use in food processing equipment, wire tinning, and alloying.[54] Susceptible to tin pest.
Sn91Zn9	199[69]		Yes	Yes	KappAloy9 Designed specifically for aluminium-to-aluminium and aluminium-to-copper soldering. It has good corrosion resistance and tensile strength. Lies between soft solder and silver brazing alloys, thereby avoiding damage to critical electronics and substrate deformation and segregation. Best solder for aluminium wire to Copper busses or copper wire to aluminium busses or contacts.[69] UNS#: L91090
Sn85Zn15	199	260[69]	Yes	No	KappAloy15 Designed specifically for aluminium-to-aluminium and aluminium-to-copper soldering. It has good corrosion resistance and tensile strength. Lies between soft solder and silver brazing alloys, thereby avoiding damage to critical electronics and substrate deformation and segregation. Has a wide plastic range this makes it ideal for hand soldering aluminium plates and parts, allowing manipulation of the parts as the solder cools.[69]
Sn80Zn20	199	288[69]	Yes	No	KappAloy20 For soldering of aluminium. Good wetting. Used extensively in spray wire form for capacitors and other electronic parts. Higher temperature and higher tensile strength compared to 85Sn/15Zn and 91Sn/9Zn.[69]
Sn70Zn30	199	316[69]	Yes	No	KappAloy30 For soldering of aluminium. Good wetting. Used extensively in spray wire form for capacitors and other
Sn60Zn40	199	343[69]	Yes	No	KappAloy40 For soldering of aluminium. Good wetting. Used extensively in spray wire form for capacitors and other electronic parts. Higher temperature and higher tensile strength compared to 85Sn/15Zn and 91Sn/9Zn.[69]electronic parts. Higher temperature and higher tensile strength compared to 85Sn/15Zn and 91Sn/9Zn.[69]
Zn60Sn40	199	341	Yes	No	For soldering aluminium. Good wetting.[29]
Zn70Sn30	199	376	Yes	No	For soldering aluminium. Excellent wetting.[59] Good strength.
Zn95Sn5	382		Yes	yes?	For soldering aluminium. Excellent wetting.[59]
Sn90Zn7Cu3	200	222[70]	Yes	No	Kapp Eco-Babbitt[70] Commonly used in capacitor manufacturing as protective coating to shield against electromotive force (EMF) and electromagnetic interference (EMI) with the specified performance of the capacitor, to prevent current and charge leakage out of and within the layers of the capacitor, and to prevent the development of electron flows within the coating material itself, that would diminish capacitor performance, coating, and capacitor life.[70]
Sn50Zn49Cu1	200	300[71]	Yes	No	Galvanite Lead-free galvanizing solder formulation designed specifically for high quality repairs to galvanized steel surfaces. Simple, effective and easy to use, in both manufacturing and field applications. Metallurgically bonds to the steel, for a seamless protective barrier.[71]
Sn95Ag3.5Zn1Cu0.5		221[14]	Yes	No
Sn98Ag2			Yes		[55]
Sn96.5Ag3.5	221[11]		Yes	Yes	Sn96, Sn96.5, 96S. Fine lamellar structure of densely distributed Ag3Sn. Annealing at 125 °C coarsens the structure and softens the solder.[51] Creeps via dislocation climb as a result of lattice diffusion.[72] Used as wire for hand soldering rework; compatible with SnCu0.7, SnAg3Cu0.5, SnAg3.9Cu0.6, and similar alloys. Used as solder spheres for BGA/CSP components. Used for step soldering and die attachment in high power devices. Established history in the industry.[51] Widely used. Strong lead-free joints. Silver content minimizes solubility of silver coatings. Not recommended for gold.[12] Marginal wetting. Good for step soldering. Used for soldering stainless steel as it wets stainless steel better than other soft solders. Silver content does not suppress dissolution of silver metallizations.[56] High tin content allows absorbing significant amount of gold without embrittlement.[73]
Sn96Ag4	221	229	Yes	No	ASTM96TS. "Silver-bearing solder". Food service equipment, refrigeration, heating, air conditioning, plumbing.[54] Widely used. Strong lead-free joints. Silver content minimizes solubility of silver coatings. Not recommended for gold.[12]
Sn95Ag5	221	254[74]	Yes	No	Widely used. Strong lead-free joints. Silver content minimizes solubility of silver coatings. Not recommended for gold. Produces strong and ductile joints on Copper and Stainless Steel. The resulting joints have high tolerance to vibration and stress, with tensile strengths to 30,000 psi on Stainless.[74]
Sn94Ag6	221	279[74]	Yes	No	Produces strong and ductile joints on copper and stainless steel. The resulting joints have high tolerance to vibration and stress, with tensile strengths to 30,000 psi on sStainless.[74]
Sn93Ag7	221	302[74]	Yes	No	Produces strong and ductile joints on copper and stainless steel. The resulting joints have high tolerance to vibration and stress, with tensile strengths to 31,000 psi on stainless.[74] Audio industry standard for vehicle and home theater speaker installations. Its 7% silver content requires a higher temperature range, but yields superior strength and vibration resistance.[75]
Sn90Au10	217[76]		Yes	Yes
Au80Sn20	280		Yes	Yes	Au80. Good wetting, high strength, low creep, high corrosion resistance, high thermal conductivity, high surface tension, zero wetting angle. Suitable for step soldering. The original flux-less alloy, does not need flux. Used for die attachment and attachment of metal lids to semiconductor packages, e.g. kovar lids to ceramic chip carriers. Coefficient of expansion matching many common materials. Due to zero wetting angle requires pressure to form a void-free joint. Alloy of choice for joining gold-plated and gold-alloy plated surfaces. As some gold dissolves from the surfaces during soldering and moves the composition to non-eutectic state (1% increase of Au content can increase melting point by 30 °C), subsequent desoldering requires higher temperature.[77] Forms a mixture of two brittle intermetallic phases, AuSn and Au5Sn.[78] Brittle. Proper wetting achieved usually by using nickel surfaces with gold layer on top on both sides of the joint. Comprehensively tested through military standard environmental conditioning. Good long-term electrical performance, history of reliability.[37] One of the best materials for soldering in optoelectronic devices and components packaging. Low vapor pressure, suitable for vacuum work. Generally used in applications that require a melting temperature over 150 °C.[79] Good ductility. Also classified as a braze.
Sn99.3Cu0.7	228[1]		Yes	Yes	Sn99Cu1. Also designated as Sn99Cu1. Cheap alternative for wave soldering, recommended by the US NEMI consortium. Coarse microstructure with ductile fractures. Sparsely distributed Cu6Sn5.[1][80] Forms large dendritic ß-tin crystals in a network of eutectic microstructure with finely dispersed Cu6Sn5. High melting point unfavorable for SMT use. Low strength, high ductility. Susceptible to tin pest.[72] Addition of small amount of nickel increases its fluidity; the highest increase occurs at 0.06% Ni. Such alloys are known as nickel modified or nickel stabilized.[81]
Sn97Cu3	227 232	250[82] 332[52]	Yes		For high-temperature uses. Allows removing insulation from an enameled wire and applying solder coating in a single operation. For radiator repairs, stained glass windows, and potable water plumbing.
Sn99Cu0.7Ag0.3	217	228[83]	Yes	No	SCA, SAC, or SnAgCu. Tin-silver-copper alloy. Relatively low-cost lead-free alloy for simple applications. Can be used for wave, selective and dip soldering. At high temperatures tends to dissolve copper; copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn96.2Ag3.8 alloy (designated e.g. SN96Ce). Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals.
Sn99Ag0.3Cu0.7			Yes
Sn98.5Ag1.0Cu0.5	220	225	Yes	Near	SAC105 alloy contains the least amount of silver among lead-free solders. It is compatible with all flux types and is relatively inexpensive; it exhibits good fatigue resistance, wetting and solder joint reliability
Sn97Cu2.75Ag0.25	228	314[52]	Yes		High hardness, creep-resistant. For radiators, stained glass windows, and potable water plumbing. Excellent high-strength solder for radiator repairs. Wide range of patina and colors.
Sn96.5Ag3.0Cu0.5	217	220 218[16][84]	Yes	Near	SAC305. It is the JEITA recommended alloy for wave and reflow soldering, with alternatives SnCu for wave and SnAg and SnZnBi for reflow soldering. Usable also for selective soldering and dip soldering. At high temperatures tends to dissolve copper; copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn97Ag3 alloy. Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals. Weakens at thermal cycling, concern of whisker growth, large Ag3Sn intermetallic platelet precipitates causing mechanical weakening and poor shock/drop performance. Tendency to creep.[85]
Sn95.8Ag3.5Cu0.7	217	218	Yes	Near	SN96C-Ag3.5 A commonly used alloy. Used for wave soldering. Usable also for selective soldering and dip soldering. At high temperatures tends to dissolve copper; copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn96.5Ag3.5 alloy (designated e.g. SN96Ce). Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals.
Sn95.6Ag3.5Cu0.9	217		Yes	Yes	Determined by NIST to be truly eutectic.
Sn95.5Ag4Cu0.5	217[86]		Yes	Yes	SAC405. Lead-Free, Cadmium free formulation designed specifically to replace lead solders in copper and stainless steel plumbing, and in electrical and electronic applications.[87]
Sn95.5Ag3.9Cu0.6	217[88]		Yes	Yes	Recommended by the US NEMI consortium for reflow soldering. Used as balls for BGA/CSP and CBGA components, a replacement for Sn10Pb90. Solder paste for rework of BGA boards.[51] Alloy of choice for general SMT assembly.
Sn95.5Ag3.8Cu0.7	217[89]		Yes	Near	SN96C. Preferred by the European IDEALS consortium for reflow soldering. Usable also for selective soldering and dip soldering. At high temperatures tends to dissolve copper; copper buildup in the bath has detrimental effect (e.g. increased bridging). Copper content must be maintained between 0.4–0.85%, e.g. by refilling the bath with Sn96.2Ag3.8 alloy (designated e.g. SN96Ce). Nitrogen atmosphere can be used to reduce losses by dross formation. Dull, surface shows formation of dendritic tin crystals.
Sn95.5Cu4Ag0.5	226	260[87]	Yes	No	KappFree provides good joint strength, vibration resistance, and thermal cycle fatigue resistance in both piping and electrical products as opposed to tin-lead solders. Higher working temperature. Wets well to brass, copper, and stainless steel. Good electrical conductivity.[87]
Sn95Ag4Cu1			Yes
Sn90.7Ag3.6Cu0.7Cr5	217	1050[90]	Yes	No	C-Solder. Lead-free, low-temperature soldering alloy for joining of various carbon materials including carbon fibres and carbon nanotube fibres in both carbon-carbon and carbon-metal arrangements. Produces mechanically strong and electrically conductive bonds. Provides wetting of carbon[91] and other materials generally considered as difficult to solder, including aluminium, stainless steel, titanium, glass, and ceramics.
Sn65Ag25Sb10	233		Yes	Yes	Very high tensile strength. For die attachment. Very brittle. Old Motorola die attach solder.
Sn96.2Ag2.5Cu0.8Sb0.5	217[16]	225	Yes		Ag03A. Patented by AIM alliance.
Sn95.25Ag3.8Cu0.7Sb0.25			Yes		Preferred by the European IDEALS consortium for wave soldering.
Sn99.3Cu0.7Ni0.05Ge0.009	227[92]			Yes	Sn100C, a lead-free silver-free nickel-stabilized alloy. Similar to Sn99Cu1. The nickel content lowers copper erosion and promotes shiny solder fillet. The presence of germanium promotes flow and reduces dross formation. Performance similar to SAC alloys at lower cost. Dross formation rate comparable to lead-tin alloys.
Sn99Sb1	232	235[93]	Yes	No
Sn97Sb3	232	238[94]	Yes	No
Sn95Sb5	235 232	240[11][16]	Yes	No	Sb5, ASTM95TA. The US plumbing industry standard. It displays good resistance to thermal fatigue and good shear strength. Forms coarse dendrites of tin-rich solid solution with SbSn intermetallic dispersed between. Very high room-temperature ductility. Creeps via viscous glide of dislocations by pipe diffusion. More creep-resistant than SnAg3.5. Antimony can be toxic. Used for sealing chip packagings, attaching I/O pins to ceramic substrates, and die attachment; a possible lower-temperature replacement of AuSn.[72] High strength and bright finish. Use in air conditioning, refrigeration, some food containers, and high-temperature applications.[54] Good wettability, good long-term shear strength at 100 °C. Suitable for potable water systems. Used for stained glass, plumbing, and radiator repairs.
Zn100	419		Yes	Pure	For soldering aluminium. Good wettability of aluminium, relatively good corrosion resistance.[29]
Zn95Al5	382		Yes	Yes	For soldering aluminium. Good wetting.[29]
Au87.5Ge12.5	361 356[16]		Yes	Yes	Au88. Used for die attachment of some chips.[11] The high temperature may be detrimental to the chips and limits reworkability.[37]
Au98Si2	370	800[16]	Yes		Au98. A non-eutectic alloy used for die attachment of silicon dies. Ultrasonic assistance is needed to scrub the chip surface so a eutectic (3.1% Si) is reached at reflow.
Au96.8Si3.2	370[16]	363[95]	Yes	Yes	Au97.[77] AuSi3.2 is a eutectic with melting point of 363 °C. AuSi forms a meniscus at the edge of the chip, unlike AuSn, as AuSi reacts with the chip surface. Forms a composite material structure of submicron silicon plates in soft gold matrix. Tough, slow crack propagation.[80]

Notes on the above table

In the Sn-Pb alloys, tensile strength increases with increasing tin content. Indium-tin alloys with high indium content have very low tensile strength.^[11]

For soldering semiconductor materials, e.g. die attachment of silicon, germanium and gallium arsenide, it is important that the solder contains no impurities that could cause doping in the wrong direction. For soldering n-type semiconductors, solder may be doped with antimony; indium may be added for soldering p-type semiconductors. Pure tin can also be used.^[59][96]

Various fusible alloys can be used as solders with very low melting points; examples include Field's metal, Lipowitz's alloy, Wood's metal, and Rose's metal.

Properties

The thermal conductivity of common solders ranges from 30 to 400 W/(m·K), and the density from 9.25 to 15.00 g/cm³.^[97][98]

Material	Thermal conductivity[98] (W/m·K)	Melting point[98] (°C)
Sn-37Pb (eutectic)	50.9	183
Sn-0.7Cu	53[1]	227
Sn-2.8Ag-20.0In	53.5	175–186
Sn-2.5Ag-0.8Cu-0.5Sb	57.26	215–217
Pb-5Sn	63	310
Lead (Pb)	35.0	327.3
Tin (Sn)	73.0	231.9
Aluminium (Al)	240	660.1
Copper (Cu)	393–401	1083
FR-4	1.7