ULTRA HIGH RELIABILITY ALLOYS AT HIGH TEMPERATURES.

Abstract

A lead-free solder alloy comprising: 2.5 to 5% by weight of silver; 0.01 to 5% by weight of bismuth; 1 to 7% by weight of antimony; 0.01 to 2% by weight of copper; one or more of: up to 6% by weight of indium, up to 0.5% by weight of titanium, up to 0.5% by weight of germanium, up to 0.5% by weight of rare earths, up to 0.5% by weight of cobalt, up to 5.0% by weight of aluminum, up to 5.0% by weight of silicon, up to 0.5% by weight of manganese, up to 0.5% by weight of chromium, up to 0.5% by weight of iron, up to 0.5% by weight of phosphorus, up to 0.5% by weight of gold, up to 1% by weight of gallium, up to 0.5% by weight of tellurium, up to 0.5% by weight of selenium, up to 0.5% by weight of calcium, up to 0.5% by weight of vanadium, up to 0.5% by weight of molybdenum, up to 0.5% by weight of platinum, and up to 0.5% by weight of magnesium; optionally up to 0.5% by weight of nickel; and the balance is tin along with any unavoidable impurities.

Description

ULTRA-HIGH RELIABILITY ALLOYS AT HIGH TEMPERATURES FIELD OF INVENTION The present invention relates generally to the field of metallurgy and, more particularly, to a soldering alloy. The soldering alloy is particularly, though not exclusively, suitable for use in electronic soldering applications such as wave soldering, surface mount technology, hot air leveling, and ball grid arrays, ground grid arrays, bottom finished packaging, LEDs, and chip-scale packaging. BACKGROUND OF THE INVENTION Lead-free solders were initially developed due to environmental and health concerns, and as replacements for conventional soft solder alloys. Many conventional lead-free solder alloys are based around the eutectic composition Sn-0.7 wt. Cu. The tin-silver-copper system has also been adopted by the electronics industry as a lead-free alternative for solder materials. For example, the near-eutectic composition 96.5Sn3.OAgO.5Cu exhibits superior fatigue strength compared to the eutectic Sn-Pb solder, while having a melting point in the range of approximately 217 to 220 °C. q Lzznn / zznz / E / viAi Ref. 331804 As the use of lead-free solder becomes more common, whether due to environmental guidelines or pressure from end users, the range of applications for such materials is also expanding. In some fields, such as automotive and high-power electronics, including LED lighting, solder alloys that can operate at higher temperatures, for example, 150°C or more, for a relatively longer time are preferred. However, the 96.5Sn3.OAgO.5Cu alloy does not perform well at such temperatures. Several attempts have been made to find better-performing alternatives to 96.5Sn3.OAgO.5Cu. U.S. Patent No. 10,376,994B2 relates to a solder material based on Sn, Ag, and Cu. U.S. Patent No. 2016 / 0325384A1 relates to high-reliability, lead-free solder alloys for harsh environments and electronic applications. Patent No. EP3321025A1 relates to a lead-free solder alloy, a flux composition, a solder paste composition, an electronic circuit board, and an electronic control device. U.S. Patent No. 10,195,698B2 relates to high-reliability, lead-free solder alloys. 10,300,56262 relates to an alloy for Lzznn / zznz / E / viAi soldering, a soldering paste, and an electronic circuit board. Patent No.WO2019 / 094242A1 relates to an alternative tin-based, low-silver solder alloy for standard SAC alloys for high-reliability applications. Patent No. WO2019 / 094243A1 relates to a high-reliability, lead-free solder alloy for electronic applications in extreme environments. However, neither of these alternatives provides a favorable combination of high-temperature reliability and favorable mechanical properties. SUMMARY OF THE INVENTION The present invention seeks to solve at least some of the problems associated with the prior art or to provide a commercially acceptable alternative. Accordingly, in a first aspect, the present invention provides a lead-free soldering alloy comprising: q Lzznn / zznz / E / viAi 2.5 to 5% by weight of silver; 0.01 to 5% by weight of bismuth; 1 to 7% by weight of antimony; 0.01 to more than 2% by weight of copper; up to 6% by weight of indium; up to 0.5% by weight of titanium. up to 0.5% by weight of germanium, up to 0.5% by weight of rare earths, up to 0.5% by weight of cobalt, up to 5.0% by weight of aluminum, up to 5.0% by weight of silicon, 5 up to 0.5% by weight of manganese, up to 0.5% by weight of chromium, up to 0.5% by weight of iron, up to 0.5% by weight of phosphorus, up to 0.5% by weight of gold, 10 up to 1% by weight of gallium, up to 0.5% by weight of tellurium, up to 0.5% by weight of selenium, up to 0.5% by weight of calcium, up to 0.5% by weight of vanadium, 15 up to 0.5% by weight of molybdenum, up to 0.5% by weight of platinum, and up to 0.5% by weight of magnesium; optionally up to 0.5% by weight of nickel; and 20 the balance is tin together with any unavoidable impurities. q Lzznn / zznz / E / YiAi BRIEF DESCRIPTION OF THE FIGURES The present invention will now be described in greater detail below with reference to the following figures in which: Figure 1 shows a micrograph of a welding alloy according to the present invention. Figure 2 shows a graph of solidus and liquidus temperatures for alloys with varying Sb contents. Figure 3 shows a graph of solidus and liquidus temperatures for alloys with varying Sb and Bi contents. Figure 4 shows a graph of hardness values ​​for alloys with varying Sb and Cu contents. Figure 5 shows a graph of hardness values ​​for alloys with varying Sb and Bi contents. Figure 6 shows micrographs of a series of welding alloys according to the present invention. Figure 7 shows a graph of the ultimate tensile strengths (UTS) of a series of welding alloys according to the present invention and Sn3CuO.5Ag. Figure 8 shows a graph of the elastic limits (YS) of a series of welding alloys according to the present invention and Sn3CuO.5Ag. Figure 9 shows a graph of the yield strengths at 150 °C and 200 N of a series of welding alloys according to the present invention and Sn3CuO.5Ag. Figure 10 shows a graph of yield elongations at 150 °C and 200 N of a series of welding alloys according to the present invention and Sn3CuO.5Ag Figure 11 shows a micrograph of a BGA formed using the welding alloy according to the present invention. Figure 12 shows Weibull distribution charts of in-situ monitored BGA228 failures for a series of welding alloys according to the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in greater detail. Different aspects of the invention are defined in greater detail in the following passages. Each aspect thus defined may be combined with any other aspect or aspects unless clearly stated otherwise. In particular, any feature stated as preferred or advantageous may be combined with any other feature or features stated as preferred or advantageous. The term solder alloy used herein encompasses a fusible metallic alloy with a melting point in the range of 90 to 400 °C. The alloys are preferably lead-free, meaning that no lead is intentionally added. Therefore, the lead content is zero or no greater than accidental impurity levels. The welding alloy may exhibit improved high-temperature reliability and may be able to withstand operating temperatures of typically at least 150 °C. The welding alloy may exhibit improved mechanical properties and high-temperature creep resistance compared to the conventional 96.5SnAg3.OCuO.5 alloy. The welding alloy may have a high melting point, specifically a liquidus temperature greater than 210 °C and less than 260 °C. The welding alloy preferably has a liquidus temperature greater than 212 °C, more preferably greater than 215 °C, more preferably greater than 218 °C, and still more preferably greater than 220 °C. A higher liquidus temperature may allow the alloy to be used in a higher-temperature welding process. The welding alloy preferably has a liquidus temperature less than 250 °C, more preferably less than 240 °C, and still more preferably less than 235 °C.Such liquidus temperatures can be advantageous because peak reflow temperatures are typically 25 to 30 °C above the liquidus temperature, and reflow temperatures greater than approximately 260 °C can lead to various problems during soldering, such as damage to circuit boards and printed components. Welding alloys may exhibit favorable mechanical properties and weldability. They may also exhibit superior creep properties at high temperatures, as well as superior thermomechanical properties and fatigue strength, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. Welding alloys may exhibit superior thermal cycling and / or thermal shock performance under harsh environmental conditions, such as -40 to 150 °C, with a dwell time of 30 minutes at each temperature. Alloy additions are used to modify the microstructure of the alloy and, consequently, its properties due to metallurgical physical mechanisms such as precipitation strengthening, solid solution strengthening, grain refinement, and diffusion control. Advantageously, the magnitude of the mechanical properties of the soldering alloy, such as hardness, tensile strength, and high-temperature creep, can be at least twice that of 96.5SnAg3.OCuO.5. Bismuth, antimony, and indium, for example, affect the solidus and liquidus temperatures of the soldering alloy. These elements also have high solid solubility in tin and can therefore contribute significantly to strengthening the solid solution of the matrix. Changes in the solidus or liquidus temperatures do not appear to adversely affect the mechanical properties of the alloys. The diffusion-dependent creep strain q Lzznn / zznz / E / viAi depends on the homologous temperature, that is, the ratio of the test temperature to the melting temperature of the material on an absolute scale. The homologous temperature of the welding alloy may be in the range of 0.84 to 0.86. Therefore, the melting temperature of the welding alloy does not have a significant effect on the mechanical properties. An optimal combination of solid solution and precipitation strengthening can result in a distributed network of precipitate particles within a strong matrix. The precipitate particles can include, for example, AgsSn and (Cu,Ni)gSn5. The precipitate network resists grain boundary movement during creep deformation, thereby improving creep resistance. The solder alloy comprises 2.5 to 5.0 wt% silver. The solder alloy preferably comprises 2.8 to 4.5 wt% silver, with 3 to 4 wt% silver being more preferred. The presence of silver in the specified amount can improve mechanical properties, such as strength, through the formation of network-like intermetallic compounds such as, for example, AgaSn. Furthermore, the presence of silver can improve wetting and spreading. Higher levels of silver, particularly above 4.5 wt%, can increase the liquid temperature, and the larger AgsSn precipitates formed in the solder matrix can act as crack initiation sites and lead to subsequent failure. Lower silver contents may not form sufficient AgsSn precipitates to improve strength. The welding alloy comprises 0.01 to 5 wt% bismuth. Preferably, the welding alloy comprises 1.0 to 4.0 wt% bismuth, more preferably 2.0 to 4.0 wt% bismuth, even more preferably 2.5 to 4 wt% bismuth, still more preferably 2.8 to 4 wt% bismuth, and still more preferably 3 to 4 wt% bismuth. In a preferred embodiment, the alloy comprises at least 2.8 wt% bismuth, preferably at least 3 wt% bismuth. The presence of bismuth in the specified amount can improve mechanical properties through solid solution strengthening. Bismuth can also improve creep resistance. Bismuth can also improve wetting and spreading.However, adding bismuth in excess of the specified amount can cause bismuth to precipitate onto the tin, resulting in a more brittle alloy. The welding alloy comprises 1 to 7 wt% antimony. Preferably, the welding alloy q Lzznn / zznz / E / YiAi comprises 1.0 to 6.5 wt% antimony, more preferably 2 to 6 wt% antimony, even more preferably 3 to 6 wt% antimony, still more preferably 3.1 to 6 wt% antimony, and still more preferably 3.2 to 6 wt% antimony. In a preferred embodiment, the alloy comprises at least 3 wt% antimony, preferably at least 3.1 wt% antimony, and even more preferably at least 3.2 wt% antimony. The presence of antimony in the specified amount can serve to improve the mechanical properties through solid solution strengthening. The antimony can also act to improve creep resistance and thermal fatigue resistance. The antimony can also raise the liquidus temperature of the alloy.Adding less antimony than the specified range may not provide the required improvement in mechanical strength and thermal fatigue resistance. Adding more antimony than the specified range can raise the liquidus temperature, thus increasing the prescribed reflow temperature. Reflow temperatures above 260°C can cause various problems during soldering, such as damage to printed circuit boards and components. The solder alloy comprises 0.01 to 2 wt% copper. The preferably solder alloy q Lzznn / zznz / E / viAi comprises 0.3 to 1.2 wt% copper, preferably 0.4 to 0.8 wt% copper. The presence of copper in the specified amount can serve to improve mechanical properties, for example, strength, through the formation of Cu-Sn intermetallic compounds. The addition of copper within the specified range results in the optimum amount of precipitated intermetallic compounds necessary to strengthen the alloy. The solder alloy optionally comprises up to 0.5 wt% nickel, e.g., from 0.001 to 0.5 wt%. The solder alloy preferably comprises nickel. The solder alloy preferably comprises from 0.001 to 0.4 wt% nickel, more preferably from 0.01 to 0.3 wt% nickel, and even more preferably from 0.02 to 0.2 wt% nickel. The presence of nickel in the specified amount can improve mechanical properties through the formation of intermetallic compounds with tin and copper, which can result in enhanced precipitation. In addition, the presence of nickel can reduce the copper dissolution rate. Nickel can also increase thermal reliability by decreasing the IMG rise at the substrate / solder interface. The welding alloy optionally comprises up to 6% by weight of indium, e.g., from 0.001 to 6% by weight of indium. The welding alloy preferably comprises indium. The welding alloy preferably comprises from 0.001 to 5.5 wt% indium, more preferably from 0.02 to 4 wt% indium, and even more preferably from 0.5 to 3 wt% indium. The presence of indium in the specified amount can serve to improve mechanical properties through solid solution or precipitate strengthening. The addition of indium can also lower the solidus and liquidus temperatures, with a greater effect on reducing the solidus temperature. Higher levels of indium can result in the formation of low-temperature phases that will adversely affect the long-term reliability of the alloys. The welding alloy optionally comprises up to 0.5 wt% titanium, e.g., from 0.01 to 0.5 wt% titanium. The welding alloy preferably comprises titanium. The welding alloy preferably comprises from 0.001 to 0.3 wt% titanium, more preferably from 0.005 to 0.2 wt% titanium, and even more preferably from 0.007 to 0.05 wt% titanium. The presence of titanium in the specified amounts may improve one or more of the strength, solid-state interfacial reactions, and thermomechanical reliability. The welding alloy optionally comprises up to 0.5 wt% germanium, e.g., from 0.01 to 0.5 wt% germanium. The welding alloy preferably comprises germanium. The welding alloy preferably comprises from 0.001 to 0.3 wt% germanium, more preferably from 0.001 to 0.1 wt% germanium, and even more preferably from 0.001 to 0.02 wt% germanium. The presence of germanium can improve mechanical properties through particle dispersion. Germanium can also aid in deoxidation and improve wettability, strength, and appearance of the weld joints. Furthermore, germanium in combination with nickel and / or titanium can improve thermomechanical fatigue properties. The welding alloy optionally comprises up to 0.5 wt% of rare earth elements, e.g., from 0.001 to 0.5 wt% of rare earth elements. The welding alloy preferably comprises rare earth elements. The term "rare earth element," as used herein, refers to one or more elements selected from Se, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The welding alloy preferably comprises from 0.002 to 0.3 wt% of rare earth elements, with greater preference from 0.003 to 0.05 wt% of rare earth elements. Preferred rare earth elements include cerium, neodymium, and lanthanum. The presence of rare earth elements can improve mechanical properties by dispersing particles and / or modifying the microstructure. Rare earth elements can also improve spread and wettability. The welding alloy optionally comprises up to 0.5 wt% cobalt, for example, from 0.001 to 0.5 wt% cobalt. The welding alloy preferably comprises cobalt. The welding alloy preferably comprises from 0.01 to 0.2 wt% cobalt, more preferably from 0.01 to 0.2 wt% cobalt, and even more preferably from 0.02 to 0.1 wt% cobalt. The presence of cobalt in the specified amounts may improve the strength and / or high-temperature properties of the weld. In a preferred embodiment, the alloy is cobalt-free. This may be advantageous in view of the high cost and toxicity of cobalt. The welding alloy optionally comprises up to 5 wt% aluminum, e.g., from 0.001 to 5 wt% aluminum. The welding alloy preferably comprises aluminum. The weld preferably comprises from 0.001 to 3 wt% aluminum, more preferably from 0.005 to 2 wt% aluminum, even more preferably from 0.01 to 1.5 wt% aluminum, still more preferably from 0.015 to 1 wt% aluminum, and still more preferably from 0.02 to 0.08 wt% aluminum. The presence of aluminum in the aforementioned amounts can improve the fatigue strength of the weld. The solder alloy optionally comprises up to 5 wt% silicon, e.g., from 0.001 to 5 wt% silicon. The solder alloy preferably comprises silicon. The solder preferably comprises from 0.001 to 3 wt% silicon, more preferably from 0.005 to 2 wt% silicon, even more preferably from 0.01 to 1.5 wt% silicon, still more preferably from 0.015 to 1 wt% silicon, and still more preferably from 0.02 to 0.08 wt% silicon. The presence of silicon in the aforementioned amounts can improve the mechanical properties, fatigue strength, and thermal and electrical conductivity of the solder. The welding alloy optionally comprises one or more of: up to 0.5 wt% chromium, preferably from 0.001 to 0.5 wt% chromium; up to 0.5 wt% manganese, preferably from 0.001 to 0.5 wt% manganese, more preferably from 0.003 to 0.015 wt% manganese, even more preferably from 0.005 to 0.01 wt% manganese; up to 0.5 wt% iron, preferably from 0.01 to 0.5 wt% iron, more preferably from 0.01 to 0.1 wt% iron, even more preferably from 0.015 to 0.035 wt% iron or from 0.85 to 0.95 wt% iron; up to 0.5% by weight of phosphorus, preferably from 0.001 to 0.5% by weight of phosphorus; up to 0.5% by weight of gold, preferably from 0.001 to 0.5% by weight of gold; up to 1% by weight of gallium, preferably from 0.01 to 0.9% by weight of gallium, more preferably from 0.2 to 0.8% by weight of gallium, even more preferably from 0.4 to 0.6% by weight of gallium; up to 0.5% by weight of tellurium, preferably from 0.001 to 0.5% by weight of tellurium; up to 0.5% by weight of selenium, preferably from 0.001 to 0.5% by weight of selenium; up to 0.5% by weight of calcium, preferably from 0.001 to 0.5% by weight of calcium; up to 0.5% by weight of vanadium, preferably from 0.001 to 0.5% by weight of vanadium; up to 0.5% by weight of molybdenum, preferably from 0.001 to 0.5% by weight of molybdenum; up to 0.5% by weight of platinum, preferably from 0.001 to 0.5% by weight of platinum; and up to 0.5% by weight of magnesium, preferably from 0.001 to 0.5% by weight of magnesium. Aluminum, calcium, gallium, germanium, magnesium, phosphorus, and vanadium can act as deoxidizers and can also improve wettability and weld joint strength. Other elemental additions, such as gold, chromium, iron, manganese, molybdenum, platinum, selenium, and tellurium, can improve strength and interfacial reactions.Aluminum combined with silicon can improve the strength and reliability of alloys. Germanium combined with silicon can also improve the strength and reliability of alloys. The welding alloy preferably comprises one to three elements, preferably one or two elements, with greater preference two elements selected from nickel, titanium, germanium, indium, manganese, rare earths, cobalt, aluminum, silicon, chromium, iron, phosphorus, gold, gallium, tellurium, selenium, calcium, vanadium, molybdenum, platinum and magnesium, preferably selected from nickel, titanium, germanium, indium, manganese, rare earths, cobalt, silicon, iron and gallium. The brazing alloy preferably comprises nickel and indium, or nickel and manganese, or nickel and germanium, or nickel, indium and neodymium, or nickel and titanium, or nickel and cerium, or indium, or indium, titanium and germanium, or nickel, or neodymium, or germanium, or silicon, or nickel and iron, or nickel and silicon, or nickel and cobalt, or cobalt and manganese, or manganese, or manganese and iron, or cobalt and germanium, or cobalt and titanium, or nickel and gallium, or indium and cobalt.Such an alloy may exhibit favorable mechanical properties. The welding alloy preferably comprises nickel and one of titanium, germanium, indium, manganese, rare earth elements, cobalt, aluminum, silicon, chromium, iron, phosphorus, gold, gallium, tellurium, selenium, calcium, vanadium, molybdenum, platinum, and magnesium, preferably selected from nickel, titanium, germanium, indium, manganese, rare earth elements, cobalt, silicon, iron, and gallium, preferably one of titanium, germanium, manganese, cobalt, and indium, with greater preference one of titanium, germanium, and manganese. Such an alloy may exhibit favorable mechanical properties. The weight percentage of antimony is preferably greater than the weight percentage of bismuth. Such an alloy can exhibit favorable mechanical properties, particularly high strength. When the bismuth content is also controlled to not exceed approximately 4% by weight, high strength can be combined with low brittleness.The sum of the weight percent of antimony and bismuth is preferably greater than or equal to 6.5, with a higher preference for greater than or equal to 7.5. This can increase the alloy's strength. The sum of the weight percent of antimony and bismuth is preferably less than or equal to 12, with a higher preference for less than or equal to 11. This can result in a solidus-liquidus gap, typically less than or equal to approximately 14 °C. This can also prevent the occurrence of an unfavorably high liquidus temperature. For example, the sum of the weight percent of antimony and bismuth is preferably 6.5 to 12, with a higher preference for 6.5 to 11, and even more preferably 7.5 to 10. Such an alloy may exhibit favorable mechanical properties.In particular, an alloy of this type can exhibit a favorable combination of high strength and a low solidus-liquidus temperature difference, typically less than approximately 14 °C, and a desirable liquidus temperature. When the sum of the weight percent of antimony and the weight percent of bismuth are controlled to be in the amounts shown in the above Lzznn / zznz / E / YiAi, and when the bismuth content is also controlled to not exceed 4 weight percent, particularly favorable mechanical properties can be obtained. The reasoning is as follows. Bismuth has a maximum solubility of approximately 4 weight percent, while antimony has a maximum solubility of 3 weight percent in Sn at room temperature. Antimony contributes to significant strengthening of the solid solution at least up to 150 °C. A greater strength-enhancing effect of antimony is obtained if the maximum solubility of bismuth is not exceeded.A bismuth content greater than 4% by weight may not lead to a further increase in strength, as it precipitates an excess of bismuth, and may even be detrimental to mechanical behavior by increasing the brittleness of the alloy. In a particularly preferred embodiment, the alloy consists of: 2.5 to 4% by weight of silver; 2.8 to 4.2% by weight of bismuth, preferably 2.8 to 4% by weight of bismuth; 3.2 to 6.2% by weight of antimony; from 0.4 to 0.8% by weight of copper; from 0.04 to 0.18% by weight of nickel; one of: from 0.007 to 0.05 wt% titanium, q Lzznn / zznz / E / YiAi from 0.001 to 0.02 wt% germanium, and from 0.005 to 0.01 wt% manganese; and the balance is tin together with any unavoidable impurities, wherein: The weight percent of antimony is greater than the weight percent of bismuth, and the sum of the weight percent of antimony and the weight percent of bismuth is greater than or equal to 6.5. Such an alloy can exhibit a particularly favorable combination of mechanical properties, weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue resistance, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. Furthermore, the alloy is cobalt-free. This can be advantageous given the high cost and toxicity of cobalt. In another particularly preferred embodiment, the welding alloy comprises: 3 to 5% by weight of silver; from 0.01 to 0.2% by weight of bismuth; 4 to 6% by weight of antimony; from 0.3 to 1% by weight of copper; q Lzznn / zznz / E / YiAi one or more of: up to 6% by weight of indium, up to 0.5% by weight of titanium, up to 0.5% by weight of kermanium, up to 0.5% by weight of rare earths, up to 0.5% by weight of cobalt, up to 5.0% by weight of aluminum, up to 5.0% by weight of silicon, up to 0.5% by weight of manganese, up to 0.5% by weight of chromium, up to 0.5% by weight of iron, up to 0.5% by weight of phosphorus, up to 0.5% by weight of gold, up to 1% by weight of gallium, up to 0.5% by weight of tellurium, up to 0.5% by weight of selenium, up to 0.5% by weight of calcium, up to 0.5% by weight of vanadium, up to 0.5% by weight of molybdenum, up to 0.5% by weight of platinum, up to 0.5% by weight of manganese; and the balance is tin along with any inevitable impurities. Such an alloy may exhibit a particularly favorable combination of mechanical properties, such as favorable weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue strength, as evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. Such an alloy may be nickel-free, i.e., it may contain nickel at no more than unavoidable impurity levels. This can be advantageous since nickel is toxic and prohibited in certain jurisdictions for use in products that come into contact with consumers. The alloy may consist of the elements listed. The welding alloy preferably has a solidus-liquidus temperature difference of less than 16 °C, preferably less than or equal to 14 °C, and more preferably less than or equal to 12 °C. An excessively large solidus-liquidus temperature difference can cause welding defects due to the soft zone formed before complete solidification of the weld. The solder alloy of any aspect is preferably in the form of a bar, rod, solid core or flux-cored wire, metal foil or strip, film, preform, powder or paste (powder plus flux mixture), solder spheres for use in ball grid array joints, a preformed solder piece or a solidified or reflowed solder joint, or previously applied to any solderable material, such as copper tape for photovoltaic applications or a printed circuit board of any type. The alloy will typically comprise at least 70% by weight of tin, more typically at least 80% by weight of tin, still more typically at least 84% by weight of tin. It will be noted that the alloys described herein may contain unavoidable impurities, although, in total, these are unlikely to exceed 1% by weight of the composition. Preferably, the welding alloys contain unavoidable impurities in an amount not greater than 0.5% by weight of the composition, more preferably not greater than 0.3% by weight of the composition, even more preferably not greater than 0.1% by weight of the composition, even more preferably not greater than 0.05% by weight of the composition, and most preferably not greater than 0.02% by weight of the composition. The soldering alloys described herein may consist of the elements mentioned. Alternatively, the soldering alloys described herein may consist essentially of the elements mentioned. Therefore, it will be appreciated that in addition to those elements that are mandatory (i.e., tin, bismuth, antimony, and copper), other unspecified elements may be present in the composition, provided that the essential characteristics of the composition are not materially affected by their presence. The alloys of the present invention can be manufactured by mixing the corresponding pure elements, or by mixing prefabricated alloys, in any form factor, and using any manufacturing method, if their final compositions are covered by the specification described herein. In a preferred embodiment, the alloy consists of 2.8 to 3.2 wt% silver, 2.8 to 3.2 wt% bismuth, 4.5 to 5.5 wt% antimony, 0.3 to 0.8 wt% copper, 0.08 to 0.2 wt% nickel, 0.001 to 0.01 wt% germanium, and the remainder is tin along with unavoidable impurities. Such an alloy may exhibit a particularly favorable combination of mechanical properties, weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue strength, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. In a preferred embodiment, the solder alloy consists of 2.8 to 3.2 wt% silver, 2.8 to 3.2 wt% bismuth, 5.5 to 6.5 wt% antimony, 0.3 to 0.8 wt% copper, 0.08 to 0.2 wt% nickel, 0.005 to 0.02 wt% titanium, and the balance is tin along with unavoidable impurities. Such an alloy can exhibit a particularly favorable combination of mechanical properties, weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue strength, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. In a preferred embodiment, the alloy consists of 3.1 to 3.7 wt% silver, 3 to 3.5 wt% bismuth, 3 to 3.8 wt% antimony, 0.4 to 0.9 wt% copper, 0.01 to 0.9 wt% nickel, 0.001 to 0.01 wt% germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy consists of 3.2 to 3.9 wt% silver, 3.5 to 4.5 wt% bismuth, 5.5 to 6.5 wt% antimony, 0.3 to 0.9 wt% copper, 0.05 to 0.12 wt% nickel, 0.001 to 0.01 wt% manganese, and the balance is tin along with unavoidable impurities. Such an alloy can exhibit a particularly favorable combination of mechanical properties, weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue strength, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. In a preferred embodiment, the alloy consists of 3.5 to 4.2 wt% silver, 0.01 to 0.1 wt% bismuth, 5 to 6 wt% antimony, 0.4 to 0.9 wt% copper, 0.001 to 0.01 wt% germanium, 0.2 to 0.8 wt% indium, 0.02 to 0.08 wt% cobalt, and the remainder is tin along with unavoidable impurities. Such an alloy can exhibit a particularly favorable combination of mechanical properties, weldability, superior creep properties at high temperatures, and superior thermomechanical properties and fatigue strength, such as those evaluated in thermal cycling or thermal shock tests covering a wide temperature range and extended dwell times. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 1 to 3 wt% antimony, 2 to 4 wt% bismuth, 0.3 to 1 wt% copper, 0.1 to 0.25 wt% nickel, 0.5 to 3.5 wt% indium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 202.8 to 217.9 °C, which is lower than the near eutectic temperature of the conventional alloy 96.5Sn3.OAgO.5Cu. This alloy has a hardness and tensile strength that are approximately twice the magnitude of the hardness of 96.5Sn3.OAgO.5Cu. The creep fracture time is 2.5 times that of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3% by weight of silver, approximately 3.1% by weight of bismuth, approximately 2.1% by weight of antimony, approximately 0.8% by weight of copper, approximately 0.25% by weight of nickel, approximately 3.3% by weight of indium and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4.5 wt% silver, 1 to 3 wt% antimony, 2.5 to 4 wt% bismuth, 0.5 to 1.5 wt% copper, 0.1 to 0.25 wt% nickel, 0.5 to 1.5 wt% indium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 209.7 to 223.5 °C and a hardness that is approximately twice the magnitude of the hardness of 96.5SnAg3.OCuO.5. The creep fracture time of this alloy is 2.5 times that of 96.5Sn3.OCuO.5Cu. In a specific example of this modality, the alloy comprises approximately 3% by weight of silver, 3.1% by weight of bismuth, 2.1% by weight of antimony, 0.75% by weight of copper, 0.2% by weight of nickel, 1.2% by weight of indium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4.5 wt% silver, 2 to 4 wt% bismuth, 3.5 to 6.5 wt% antimony, 0.5 to 1.5 wt% copper, 0.05 to 0.2 wt% nickel, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 203.3 to 236.1 °C and a tensile strength and yield strength time that is more than twice that of 96.5Sn3.OAgO.5Cu. In a specific example of this embodiment, the alloy comprises approximately 3.6 wt% silver, 3.9 wt% bismuth, 4 wt% antimony, 0.7 wt% copper, 0.1 wt% nickel, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4.5 wt% bismuth, 5 to 6.5 wt% antimony, 0.5 to 1 wt% copper, 0.05 to 0.2 wt% nickel, 0.001 to 0.01 wt% manganese, and the balance is tin along with unavoidable impurities. In this preferred embodiment, the alloy preferably consists of 3.2 to 4 wt% silver, 3.5 to 4.5 wt% bismuth, 5.5 to 6.5 wt% antimony, 0.3 to 0.09 wt% copper, 0.05 to 0.12 wt% nickel, 0.001 to 0.01 wt% manganese, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 197.4 to 231.6 °C. In a specific example of this form, the alloy comprises approximately 3.5 wt% silver, 4.2 wt% bismuth, 6.1 wt% antimony, 0.7 wt% copper, 0.1 wt% nickel, 0.005 wt% manganese, and the remainder is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 3.5 to 4.5 wt% antimony, 0.3 to 0.8 wt% copper, 0.02 to 0.3 wt% nickel, 0.001 to 0.002 wt% germanium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 211.4 to 225.5 °C. Such an alloy has more than twice the tensile strength and creep rupture time of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises 3.2% by weight of silver, 3.4% by weight of bismuth, 0.5% by weight of copper, 3.9% by weight of antimony, 0.15% by weight of nickel, 0.001% of germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 2.5 to 3.5 wt% bismuth, 4 to 5.5 wt% antimony, 0.3 to 0.8 wt% copper, 0.1 to 0.2 wt% nickel, 0.001 to 0.002 wt% germanium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 215.2 to 228.3 °C. Such an alloy has more than twice the tensile strength of 96.5Sn3.OAgO.5Cu. The creep fracture time of the alloy is four times that of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3.2% by weight of silver, 3% by weight of bismuth, 0.5% by weight of copper, 4.9% by weight of antimony, 0.15% by weight of nickel, 0.001% by weight of germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.3 to 0.8 wt% copper, 3 to 4 wt% indium, 5.5 to 6.5 wt% antimony, 0.03 to 0.1 wt% nickel, 0 to 0.005 wt% some rare-earth elements (preferably neodymium), and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 186.9 to 232.9 °C. Such an alloy has more than three times the tensile strength and four times the yield strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises 3.5% by weight of silver, 3.7% by weight of bismuth, 0.55% by weight of copper, 3.4% by weight of indium, 6.1% by weight of antimony, 0.06% by weight of nickel, 0.002% of neodymium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 2.5 to 4 wt% bismuth, 0.3 to 0.8 wt% copper, 5 to 6.5 wt% antimony, 0.1 to 0.2 wt% nickel, 0.001 to 0.01 wt% titanium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 202.5 to 234.5 °C. The tensile strength of the alloy is more than twice that of 96.5Sn3.OAgO.5Cu, and its creep fracture time is six times greater. In a specific example of this modality, q Lzznn / zznz / E / YiAi the alloy comprises 3.2 of silver, 3 of bismuth, 0.5 wt% copper, 5.9 of antimony, 0.15 wt% nickel, 0.006 wt% titanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 1 wt% copper, 1 to 2 wt% copper, 5.5 to 6.5 wt% antimony, 0.18 to 0.25 wt% nickel, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 214.3 to 228.4 °C. Such an alloy has twice the tensile strength and four times the creep fracture time of 96.5Sn3.OAgO.5Cu. In a specific example of the modality, the alloy comprises approximately 3.1% by weight of silver, 3.1% by weight of bismuth, 0.7% by weight of copper, 1.15% by weight of indium, 6.1% by weight of antimony, 0.25% by weight of nickel, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 1 wt% copper, 5.5 to 6.5 wt% antimony, 0.2 to 0.3 wt% nickel, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 214 to 230.4 °C. Such an alloy has twice the tensile strength and more than three times the yield strength of 96.5Sn3.OAgO.5Cu. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.5 wt% bismuth, 0.7 wt% copper, 6.2 wt% antimony, 0.3 wt% nickel, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.4 to 0.7 wt% copper, 2.5 to 3.5 wt% indium, 5.5 to 6.5 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 195.3 to 229.3 °C. Such an alloy has more than three times the tensile strength and more than four times the creep rupture time of 96.5Sn3.OAgO.5Cu. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.7 wt% bismuth, 0.5 wt% copper, 3.4 wt% indium, 6.1 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.4 to 0.6 wt% copper, 2.5 to 3.5 wt% indium, 5.5 to 6.5 wt% antimony, 0.001 to 0.01 wt% titanium, 0.0008 to 0.002 wt% germanium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 186.5 to 232.5 °C. Such an alloy has three times the tensile strength and three times the yield strength of 96.5Sn3.OAgO.5Cu. In a specific example of q Lzznn / zznz / E / YiAi this modality, the alloy comprises approximately 3.5 wt% silver, 3.8 wt% bismuth, 0.5 wt% copper, 3.4 wt% indium, 6.1 wt% antimony, 0.006 wt% titanium, 0.001 wt% germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.8 wt% copper, 3 to 4 wt% antimony, 0.05 to 0.1 wt% nickel, 0.001 to 0.002 wt% germanium, and the balance along with unavoidable impurities. Such an alloy has a melting range of 198.9 to 230.9 °C. Such an alloy has more than twice the tensile strength and three times the creep rupture strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3.6% by weight of silver, 3.9% by weight of bismuth, 0.7% by weight of copper, 3.9% by weight of antimony, 0.09% by weight of nickel, 0.001% by weight of germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.8 wt% copper, 3 to 4 wt% antimony, 0.03 to 0.08 wt% nickel, 0.01 to 0.03 wt% titanium, and the balance is tin with unavoidable impurities. Such an alloy has a melting range of 198.9 to 227.6 °C. Such an alloy has twice the tensile strength and more than three times the creep fracture time of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3% by weight of silver, 3.2% by weight of bismuth, 0.7% by weight of copper, 3.5% by weight of antimony, 0.06% by weight of nickel, 0.02% by weight of titanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 2.5 to 3.5 wt% silver, 2.5 to 3.5 wt% bismuth, 0.3 to 0.6 wt% copper, 5.5 to 6.5 wt% antimony, 0.01 to 0.04 wt% nickel, 0.01 to 0.03 wt% titanium, and the balance is tin with unavoidable impurities. Such an alloy has a melting range of 202.6 to 229.2 °C. Such an alloy has more than three times the tensile strength and more than six times the creep rupture strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3% by weight of silver, 3.2% by weight of bismuth, 0.5% by weight of copper, 6.1% by weight of antimony, 0.03% by weight of nickel, 0.02% by weight of titanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 2.5 to 3.5 wt% silver, 2.5 to 3.5 wt% bismuth, 0.3 to 0.6 wt% copper, 5.5 to 6.5 wt% antimony, 0.001 to 0.015 wt% nickel, 0.015 to 0.035 wt% titanium, and the balance is tin with unavoidable impurities. Such an alloy has a melting range of 203.3 to 229.7 °C. Such an alloy has more than three times the tensile strength and more than six times the creep rupture strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3% by weight of silver, 3.2% by weight of bismuth, 0.5% by weight of copper, 6.1% by weight of antimony, 0.01% by weight of nickel, 0.03% by weight of titanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.4 to 0.8 wt% copper, 3 to 4 wt% antimony, 0.03 to 0.05 wt% titanium, 0.005 to 0.01 wt% germanium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 203.8 to 226.5 °C. Such an alloy has more than twice the tensile strength and four times the creep rupture strength of 96.5Sn3.OAgO.5Cu. In a specific example of this type, the alloy comprises approximately 3.4% by weight of silver, 3.5% by weight of bismuth, 0.7% by weight of copper, 3.4% in antimony, 0.002 in titanium, 0.007 in germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.8 wt% copper, 4.5 to 5.5 wt% antimony, 0.09 to 0.15 wt% nickel, 0.02 to 0.05 wt% titanium, 0.0008 to 0.0014 wt% germanium, and the balance is tin along with unavoidable impurities. In a specific example of this embodiment, the alloy comprises approximately 3 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 5.1 wt% antimony, 0.14 wt% nickel, 0.04 wt% titanium, 0.001 wt% germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.8 wt% copper, 3 to 4 wt% antimony, 0.001 to 0.012 wt% neodymium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 210.8 to 224.5 °C. Such an alloy has almost four times the creep strength of 96.5Sn3.OAgO.5Cu. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 3.8 wt% antimony, 0.005 wt% neodymium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 3 to 4 wt% antimony, 0.4 to 0.7 wt% copper, 0.02 to 0.07 wt% nickel, 0.001 to 0.005 wt% germanium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 202.9 to 224.6 °C. Such an alloy has 2.5 times the yield strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3.5% by weight of silver, 4.16% by weight of bismuth, 3.9% by weight of antimony, 0.5% by weight of copper, 0.06% by weight of nickel, 0.001% by weight of germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 4 to 6 wt% antimony, 0.4 to 0.7 wt% copper, 2.5 to 3.5 wt% indium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 195.8 to 228.6 °C. Such an alloy has twice the creep strength of 96.5Sn3.OAgO.5Cu. In a specific example of this embodiment, the alloy comprises approximately 3.8 wt% silver, 4.2 wt% bismuth, 4.7 wt% antimony, 0.5 wt% copper, 3.2 wt% indium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 1 to 2 wt% bismuth, 1 to 2 wt% copper, 3 to 4 wt% antimony, 0.008 to 0.02 wt% aluminum, 0.005 to 0.01 wt% silicon, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 217.52 to 227.05 °C. In a specific example of this embodiment, the alloy comprises approximately 3.8 wt% silver, 1.6 wt% bismuth, 1.3 wt% copper, 4 wt% antimony, 0.015 wt% aluminum, 0.007 wt% silicon, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 3 to 4 wt% antimony, 0.5 to 0.8 wt% copper, 0.03 to 0.06 wt% nickel, 0.001 to 0.008 wt% germanium, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 212.8 to 224.5 °C. In a specific example of this embodiment, the alloy comprises approximately 3.4 wt% silver, 3.3 wt% bismuth, 0.6 wt% copper, 3.4 wt% antimony, 0.05 wt% nickel, and 0.001 wt% germanium. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3.5 to 5 wt% bismuth, 0.5 to 0.8 wt% copper, 1 to 3 wt% antimony, 0.1 to 0.2 wt% nickel, and 0.01 to 0.02 wt% iron, with tin making up the balance along with any unavoidable impurities. Such an alloy has a melting range of 209.9 to 221.2 °C. Such an alloy has three times the yield strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3.4% by weight of silver, 4.1% by weight of bismuth, 0.7% by weight of copper, 2.1% by weight of antimony, 0.2% by weight of nickel, 0.02% by weight of iron, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3.5 to 4 wt% silver, 0.02 to 1 wt% bismuth, 0.5 to 0.7 wt% copper, 0.1 to 1 wt% indium, 4.5 to 6 wt% antimony, 0.03 to 0.1 wt% nickel, and the remainder is tin along with unavoidable impurities. Such an alloy has a melting range of 222.6 to 232.3 °C. Such an alloy has more than seven times the creep rupture strength of 96.5Sn3.OAgO.5Cu. In a specific example of this modality, the alloy comprises approximately 3.8% by weight of silver, 0.06% by weight of bismuth, 0.6% by weight of copper, 0.6% by weight of indium, 5.3% by weight of antimony, 0.06% by weight of nickel, and the balance is tin with the inevitable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 2.8 to 3.8 wt% bismuth, 0.5 to 0.8 wt% copper, 3.5 to 4.5 wt% antimony, 0.02 to 0.1 wt% nickel, 0.01 to 0.025 wt% silicon, and the balance together with unavoidable impurities. Such an alloy has a melting range of 214.4 to 225.6 °C. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.1 wt% bismuth, 0.6 wt% copper, 4.1 wt% antimony, 0.03 wt% nickel, 0.006 wt% silicon, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 2.5 to 3.5 wt% bismuth, 0.5 to 0.8 wt% copper, 0.02 to 0.1 wt% nickel, 0.01 to 0.03 wt% iron, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 214.4 to 226.7 °C. In a specific example of this embodiment, the alloy comprises approximately 3.6 wt% silver, 3 wt% bismuth, 0.6 wt% copper, 3.9 wt% antimony, 0.05 wt% nickel, 0.03 wt% iron, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 2.5 to 3.5 wt% silver, 2.5 to 3.5 wt% bismuth, 0.4 to 0.6 wt% copper, 5 to 6 wt% indium, 1 to 2 wt% antimony, 0.02 to 0.08 wt% nickel, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 195.1 to 211.8 °C. In a specific example of this embodiment, the alloy comprises approximately 3 wt% silver, 3.2 wt% bismuth, 0.5 wt% copper, 6 wt% indium, 1.6 wt% antimony, 0.06 wt% nickel, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3 to 4 wt% antimony, 0.02 to 0.1 wt% nickel, 0.02 to 0.08 wt% cobalt, and the balance along with unavoidable impurities. Such an alloy has a melting range of 209.6 to 224.9 °C. In a specific example of this embodiment, the alloy comprises approximately 3.4 wt% silver, 3.6 wt% bismuth, 0.6 wt% copper, 3.6 wt% antimony, 0.05 wt% nickel, 0.06 wt% cobalt, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 2.5 to 3.5 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3 to 4 wt% antimony, 0.03 to 0.1 wt% cobalt, 0.001 to 0.005 wt% manganese, and the balance is tin along with unavoidable impurities. The alloy has a melting range of 210 to 225.3 °C. In a specific example of this embodiment, the alloy comprises approximately 3 wt% silver, 3.6 wt% bismuth, 0.7 wt% copper, 3.9 wt% antimony, 0.05 wt% cobalt, 0.002 wt% manganese, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3.5 to 4.5 wt% antimony, and 0.002 to 0.01 wt% manganese. Such an alloy has a melting range of 213.9 to 224.6 °C. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, and 0.006 wt% manganese, with the remainder being tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3.5 to 4.5 wt% antimony, 0.001 to 0.005 wt% manganese, 0.01 to 0.1 wt% iron, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 214.7 to 224.6 °C. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, 0.003 wt% manganese, 0.09 wt% iron, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3.5 to 4.5 wt% antimony, 0.01 to 0.1 wt% nickel, 0.01 to 0.1 wt% cobalt, 0.005 to 0.015 wt% germanium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 215 to 225.7 °C. In a specific example of this modality, the alloy comprises approximately 3.5% by weight of silver, 3.1% by weight of bismuth, 0.7% by weight of copper, 4% by weight of antimony, 0.05% by weight of nickel, 0.05% by weight of cobalt, 0.01% by weight of germanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 2.5 to 3.5 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 4.5 to 5.5 wt% antimony, 0.02 to 0.07 wt% cobalt, 0.01 to 0.05 wt% titanium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 213.8 to 228.5 °C. In a specific example of this embodiment, the alloy comprises approximately 3 wt% silver, 3.1 wt% bismuth, 0.6 wt% copper, 5 wt% antimony, 0.06 wt% cobalt, 0.04 wt% titanium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 0.02 to 0.1 wt% bismuth, 0.5 to 0.7 wt% copper, 4.5 to 5.5 wt% antimony, 0.1 to 1 wt% gallium, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 221.9 to 229.3 °C. In a specific example of this embodiment, the alloy comprises approximately 3.7 wt% silver, 0.08 wt% bismuth, 0.6 wt% copper, 5.2 wt% antimony, 0.05 wt% nickel, 0.5 wt% gallium, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 wt% silver, 0.01 to 0.1 wt% bismuth, 0.5 to 0.7 wt% copper, 0.4 to 0.7 wt% indium, 4.5 to 5.5 wt% antimony, 0.02 to 0.08 wt% cobalt, and the balance together with unavoidable impurities. Such an alloy has a melting range of 221.6 to 229.7 °C. In a specific example of this embodiment, the alloy comprises approximately 3.7 wt% silver, 0.07 wt% bismuth, 0.6 wt% copper, 0.6 wt% indium, 5.2 wt% antimony, 0.06 wt% cobalt, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 0.5 to 2 wt% bismuth, 0.5 to 0.7 wt% copper, 3.5 to 4.5 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 219.1 to 227.5 °C. In a specific example of this embodiment, the alloy comprises approximately 3.7 wt% silver, 1.1 wt% bismuth, 0.6 wt% copper, 4 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 2.5 to 3.5 wt% bismuth, 0.5 to 0.7 wt% copper, 3 to 4 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 216.2 to 226.9 °C. In a specific example of this embodiment, the alloy comprises approximately 3.7 wt% silver, 2.1 wt% bismuth, 0.6 wt% copper, 3.9 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3 to 4 wt% bismuth, 0.5 to 0.7 wt% copper, 3 to 4 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 212.5 to 224.8 °C. In a specific example of this embodiment, the alloy comprises approximately 3.8 wt% silver, 3.2 wt% bismuth, 0.7 wt% copper, 3.6 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 3.5 to 4.5 wt% bismuth, 0.5 to 0.7 wt% copper, 3 to 4 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 210.7 to 223.9 °C. In a specific example of this embodiment, the alloy comprises approximately 3.5 wt% silver, 4 wt% bismuth, 0.6 wt% copper, 3.6 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 4.5 to 5.5 wt% bismuth, 0.4 to 0.6 wt% copper, 3 to 4 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 209.5 to 222.7 °C. In a specific example of this embodiment, the alloy comprises approximately 3.1 wt% silver, 5.1 wt% bismuth, 0.5 wt% copper, 3.7 wt% antimony, and the balance is tin along with unavoidable impurities. In a preferred embodiment, the alloy comprises 3 to 4 wt% silver, 5.5 to 6.5 wt% bismuth, 0.4 to 0.7 wt% copper, 3 to 4 wt% antimony, and the balance is tin along with unavoidable impurities. Such an alloy has a melting range of 206.2 to 220.8 °C. In a specific example of this embodiment, the alloy comprises approximately 3.2 wt% silver, 6 wt% bismuth, 0.5 wt% copper, 3.2 wt% antimony, and the balance is tin along with unavoidable impurities. In a further aspect, the present invention provides a lead-free soldering alloy comprising: (a) 2.5 to 5% by weight of silver (b) 0.01 to 5% by weight of bismuth (c) 1.0 to 7.0% by weight of antimony (d) 0.01 to 2.0% by weight of copper (e) At least one of the following elements q Lzznn / zznz / E / viAi up to 0.5% by weight of nickel up to 0.5% by weight of titanium up to 0.5% by weight of germanium Up to 5.0 wt% indium, up to 0.5 wt% manganese, up to 0.5 wt% rare earth elements such as neodymium, cerium, and lanthanum, up to 5.0 wt% aluminum, and up to 5.0 wt% silicon. (f) optionally one or more of the following elements 0 to 0.5% by weight of chromium 0 to 0.5% by weight of iron 10 0 to 0.5% by weight of phosphorus 0 to 0.5% by weight of gold 0 to 0.5% by weight of gallium 0 to 0.5% by weight of tellurium 0 to 0.5% by weight of selenium 15 0 to 0.5% by weight of calcium 0 to 0.5% by weight of vanadium 0 to 0.5% by weight of molybdenum 0 to 0.5% by weight of platinum 0 to 0.5% by weight of magnesium (g) The balance is tin, along with any unavoidable impurities. The advantages and preferable characteristics of the first aspect apply equally to this aspect. In a further aspect, the present invention provides a welding joint comprising a welding alloy as described herein. In a further aspect, the present invention provides a soldering paste comprising: the welding alloy as described in this description and a welding flux. In a further aspect, the present invention provides a method for forming a welded joint comprising: (i) provide two or more workpieces to be joined; (ii) provide a soldering alloy as described herein or a soldering paste as described herein; and (iii) heat the soldering alloy or soldering paste in the adjacent area of ​​the workpieces to join. The workpieces can be components of a printed circuit board, such as a substrate and a die. In an additional aspect, the present invention provides the use of a soldering alloy described herein or the soldering paste described herein in a soldering method. The welding method is selected, preferably, from wave soldering, surface mount technology (SMT) soldering, die fixing, thermal interface soldering, hand soldering, laser and RF induction soldering, soldering to a solar module, level 2 LED packaging board soldering, immersion soldering, and rework soldering. In a further aspect, the present invention provides a method for manufacturing the welding alloy described herein, the method comprising: to provide the aforementioned elements, and to melt the aforementioned elements, wherein the aforementioned elements may be provided in the form of individual elements and / or in the form of one or more alloys containing one or more of the aforementioned elements. The present invention will now be described in greater detail with reference to the following non-limiting examples. Example 1 - Alloy 1 Alloy 1 comprises 3 wt% silver, 3.1 wt% bismuth, 2.1 wt% antimony, 0.8 wt% copper, 3.3 wt% indium, 0.2 wt% nickel, and the balance is tin along with unavoidable impurities. Alloy 1 has a melting range of 202.8 to 217.9 °C and a Vickers hardness of 28.6 Hv. Example la - Alloy la (Reference example) The alloy contains 3.8% by weight of silver, 3% by weight of bismuth, 1.4% by weight of antimony, 0.7% by weight of copper, 0.15% by weight of nickel, and the balance is tin along with unavoidable impurities. Example Ib - Alloy Ib (Reference example) Alloy Ib contains 3.3% by weight of silver, 3.2% by weight of bismuth, 3% by weight of antimony, 0.7% by weight of copper, 0.04% by weight of nickel, 0.01% by weight of cobalt, and the balance is tin along with unavoidable impurities. Example 2 - Alloy 2 Alloy 2 comprises 3 wt% silver, 3.1 wt% bismuth, 2.1 wt% antimony, 0.7 wt% copper, 0.2 wt% nickel, 1.2 wt% indium, and the balance is tin along with unavoidable impurities. Alloy 2 has a melting range of 209.7 to 223.5 °C and a Vickers hardness of 27.2 Hv. Example 3 - Alloy 3 Alloy 3 comprises 3.6 wt% silver, 3.9 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, 0.09 wt% nickel, 0.001 wt% manganese, and the remainder is tin along with unavoidable impurities. Alloy 3 has a melting range of 203.3 to 236.1 °C. Example 4 - Alloy 4 Alloy 4 comprises 3.5 wt% silver, 4.1 wt% bismuth, 6.1 wt% antimony, 0.7 wt% copper, 0.1 wt% nickel, 0.004 wt% manganese, and the balance is tin along with unavoidable impurities. Alloy 4 has a melting range of 197.4 to 231.6 °C. A cross-section of the microstructure, in the same state as cast, of this alloy shown in Figure 6 reveals an AgaSn distribution within the tin matrix. Larger precipitates of (Cu,Ni)eSn5 and some fine intermetallic tin-bismuth precipitates are also observed. This microstructure exemplifies solid solution and precipitation strengthening, which contribute to the alloy's strength and improved mechanical properties. Example 7 - Alloy 7 Alloy 7 comprises 3.2 wt% silver, 3.4 wt% bismuth, 0.5 wt% copper, 3.9 wt% antimony, 0.16 wt% nickel, 0.001 wt% germanium, and the balance is tin along with any unavoidable impurities. The melting range of this alloy is 211.4 to 225.5 °C. Example 8 - Alloy 8 Alloy 8 consists of 3.2 wt% silver, 3 wt% bismuth, 0.5 wt% copper, 4.9 wt% antimony, 0.16 wt% nickel, 0.001 wt% germanium, and the balance is tin along with any unavoidable impurities. The melting range of this alloy is 215.2 to 228.3 °C. The bulk microstructure of this alloy, shown in Figure 6, consists of an AgsSn eutectic network along with precipitates of Bi-Sn (white) and (Cu,Ni)gSn5 (dark particles). Some of the (Cu,Ni)gSn5 precipitates tend to form a floss-like structure. This precipitate morphology suggests that the alloy will have improved mechanical properties, as shown in Figures 7, 8, and 9. Example 9 - Alloy 9 Alloy 9 comprises 3.5 wt% silver, 3.7 wt% bismuth, 0.5 wt% copper, 3.4 wt% indium, 6.1 wt% antimony, 0.06 wt% nickel, 0.002 wt% neodymium, and the remainder is tin, along with unavoidable impurities. The melting range of this alloy is from 186.9 to 232.9 °C. Example 10 - Alloy 10 Alloy 10 comprises 3.2 wt% silver, 3 wt% bismuth, 0.5 wt% copper, 5.9 wt% antimony, 0.16 wt% nickel, 0.006 wt% titanium, and the balance is tin along with any unavoidable impurities. The bulk microstructure of this alloy consists of a well-dispersed eutectic network of AgsSn, Bi-Sn, and CusSns precipitates. This alloy has a melting range of 202.5 to 234.5 °C. Example 11 - Alloy 11 Alloy 11 comprises 3.1 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 1.1 wt% indium, 6.1 wt% antimony, 0.25 wt% nickel, and the balance is tin along with any unavoidable impurities. Alloy 11 has a melting range of 214.3 to 228.4 °C. The hardness of this alloy is 32.4 Hv. Example 12 - Alloy 12 Alloy 12 comprises 3.5 wt% silver, 3.5 wt% bismuth, 0.7 wt% copper, 6.2 wt% antimony, 0.3 wt% nickel, 0.001 wt% cerium, and the remainder is tin along with unavoidable impurities. The melting range of this alloy is 213.9 to 230.4 °C. The hardness of this alloy is 28 Hv. Example 13 - Alloy 13 Alloy 13 comprises 3.5 wt% silver, 3.7 wt% bismuth, 0.5 wt% copper, 3.4 wt% indium, 6.1 wt% antimony, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 195.3 to 229.3 °C. Example 14 - Alloy 14 Alloy 14 comprises 3.5 wt% silver, 3.8 wt% bismuth, 0.5 wt% copper, 3.4 wt% indium, 6.18 wt% antimony, 0.006 wt% titanium, 0.001 wt% germanium, and the balance is tin along with any unavoidable impurities. The melting range of this alloy is from 186.5 to 232.5 °C. q Lzznn / zznz / E / viAi Example 15 - Alloy 15 Alloy 15 comprises 3.6 wt% silver, 3.9 wt% bismuth, 0.7 wt% copper, 3.9 wt% antimony, 0.09 wt% nickel, 0.001 wt% germanium, and the balance is tin along with any unavoidable impurities. The alloy has a melting range of 198.9 to 230.9 °C. Example 16 - Alloy 16 (Reference example) Alloy 16 comprises 3.5% by weight of silver, 3.2% by weight of bismuth, 0.7% by weight of copper, 3.2% by weight of antimony, 0.05% by weight of nickel, and the balance is tin along with any unavoidable impurities. Example 17 - Alloy 17 Alloy 17 comprises 3 wt% silver, 3.2 wt% bismuth, 0.7 wt% copper, 3.5 wt% antimony, 0.06 wt% nickel, 0.02 wt% titanium, and the remainder is tin along with any unavoidable impurities. Alloy 17 has a melting range of 198.9 to 227.6 °C. The bulk microstructure of this alloy is shown in Figure 6. A fine AgsSn network with well-distributed (Cu,Ni)eSn₅ and bismuth-tin precipitates is clearly visible. Example 18 - Alloy 18 Alloy 18 comprises 3% by weight of silver, 3.2% by weight of bismuth, 0.5% by weight of copper, 6.1% by weight of antimony, 0.03% by weight of nickel, 0.02% by weight of titanium, and the balance is tin along with any unavoidable impurities. Example 19 - Alloy 19 Alloy 19 comprises 3 wt% silver, 3.2 wt% bismuth, 0.5 wt% copper, 6.1 wt% antimony, 0.01 wt% nickel, 0.03 wt% titanium, and the remainder is tin along with unavoidable impurities. The melting range of Alloy 19 is 203.3 to 229.7 °C. Example 20 - Alloy 20 Alloy 20 consists of 3.4 wt% silver, 3.4 wt% bismuth, 0.7 wt% copper, 3.4 wt% antimony, 0.002 wt% titanium, 0.007 wt% germanium, and the balance is tin along with any unavoidable impurities. Alloy 20 has a melting range of 203.8 to 226.5 °C. Example 21 - Alloy 21 Alloy 21 is composed of 3% by weight silver, 3.1% by weight bismuth, 0.7% by weight copper, 5.1% by weight antimony, 0.14% by weight nickel, 0.04% by weight titanium, 0.001% by weight germanium, and the balance is tin along with any unavoidable impurities. Example 22 - Alloy 22 Alloy 22 comprises 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 3.8 wt% antimony, 0.005 wt% neodymium, and the balance is tin along with any unavoidable impurities. Alloy 22 has a melting range of 210.8 to 224.5 °C. Example 23 - Alloy 23 Alloy 23 comprises 3.5% by weight of silver, 4.2% by weight of bismuth, 0.5% by weight of copper, 3.9% by weight of antimony, 0.06% by weight of nickel, 0.001% by weight of germanium, and the balance is tin along with any unavoidable impurities. Example 24 - Alloy 24 Alloy 24 comprises 3.8 wt% silver, 4.2 wt% bismuth, 0.5 wt% copper, 3.2 wt% indium, 4.7 wt% antimony, and the balance is tin along with any unavoidable impurities. Alloy 24 has a melting range of 195.8 to 228.6 °C. Example 25 - Alloy 25 Alloy 25 comprises 3.8 wt% silver, 4.2 wt% bismuth, 0.5 wt% copper, 3.3 wt% indium, 4.6 wt% antimony, 0.001 wt% germanium, and the balance is tin along with any unavoidable impurities. The melting range of Alloy 25 is 194.5 to 220.3 °C. Example 26 - Alloy 26 Alloy 26 comprises 3.8 wt% silver, 1.6 wt% bismuth, 1.3 wt% copper, 4 wt% antimony, 0.015 wt% aluminum, 0.007 wt% silicon, and the balance is tin along with any unavoidable impurities. The melting range of Alloy 26 is 217.5 to 227.1 °C. Example 27 - Alloy 27 Alloy 27 comprises 3.4 wt% silver, 3.3 wt% bismuth, 0.6 wt% copper, 3.4 wt% antimony, 0.05 wt% nickel, 0.001 wt% neodymium, and the balance is tin along with any unavoidable impurities. The melting range of this alloy is 212.8 to 224.5 °C. Example 28 - Alloy 29 Alloy 29 comprises 3.4% by weight of silver, 4.1% by weight of bismuth, 0.7% by weight of copper, 2.1% by weight of antimony, 0.2% by weight of nickel, 0.02% by weight of iron, and the balance is tin along with unavoidable impurities. Example 29 - Alloy 31 Alloy 31 comprises 3.8 wt% silver, 0.06 wt% bismuth, 0.6 wt% copper, 0.6 wt% indium, 5.3 wt% antimony, 0.06 wt% nickel, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 222.6 to 232.3 °C. The creep strength of Alloy 31 is seven times greater than that of 96.5Sn3.OAgO.5Cu. Example 30 - Alloy 32 Alloy 32 comprises 3.5 wt% silver, 3.1 wt% bismuth, 0.6 wt% copper, 4.1 wt% antimony, 0.03 wt% nickel, 0.006 wt% silicon, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 214.4 to 225.6 °C. Example 31 - Alloy 33 Alloy 33 comprises 3.6 wt% silver, 3 wt% bismuth, 0.6 wt% copper, 3.9 wt% antimony, 0.05 wt% nickel, 0.03 wt% iron, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 214.4 to 226.7 °C. Example 32 - Alloy 34 Alloy 34 comprises 3 wt% silver, 3.2 wt% bismuth, 0.5 wt% copper, 6.3 wt% indium, 1.6 wt% antimony, 0.06 wt% nickel, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 195.1 to 211.8 °C. Example 33 - Alloy 36 (Reference example) Alloy 36 comprises 3.8 wt% silver, 4 wt% bismuth, 0.7 wt% copper, 2 wt% antimony, 0.03 wt% nickel, and the remainder is tin along with unavoidable impurities. Alloy 36 has a melting range of 208.9 to 221.9 °C. Example 34 - Alloy 37 Alloy 37 comprises 3.4 wt% silver, 3.6 wt% bismuth, 0.6 wt% copper, 3.6 wt% antimony, 0.05 wt% nickel, 0.06 wt% cobalt, and tin along with unavoidable impurities. The melting range of this alloy is 209.6 to 224.9 °C. Example 35 - Alloy 38 Alloy 38 comprises 3 wt% silver, 3.6 wt% bismuth, 0.7 wt% copper, 3.9 wt% antimony, 0.05 wt% cobalt, 0.002 wt% manganese, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 210 to 225.3 °C. Example 36 - Alloy 39 Alloy 39 comprises 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, 0.006 wt% manganese, and the remainder is tin along with unavoidable impurities. Alloy 39 has a melting range of 213.9 to 224.6 °C. Example 37 - Alloy 40 Alloy 40 comprises 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, 0.003 wt% manganese, 0.09 wt% iron, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 214.7 to 224.6 °C. Example 38 - Alloy 41 Alloy 41 comprises 3.5 wt% silver, 3.1 wt% bismuth, 0.7 wt% copper, 4 wt% antimony, 0.05 wt% nickel, 0.05 wt% cobalt, q Lzznn / zznz / E / viAi 0.01% by weight of germanium, and the balance is tin along with unavoidable impurities. The melting range of alloy 41 is 215.0 to 225.7 °C. Example 39 - Alloy 42 Alloy 42 comprises 3 wt% silver, 3.1 wt% bismuth, 0.6 wt% copper, 5 wt% antimony, 0.06 wt% cobalt, 0.04 wt% titanium, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 213.8 to 228.5 °C. Example 40 - Alloy 43 Alloy 43 comprises 3.7 wt% silver, 0.08 wt% bismuth, 0.6 wt% copper, 5.2 wt% antimony, 0.05 wt% nickel, 0.5 wt% gallium, and the remainder is tin along with unavoidable impurities. Alloy 43 has a melting range of 221.9 to 229.3 °C. Example 41 - Alloy 45 Alloy 45 comprises 3.7 wt% silver, 0.07 wt% bismuth, 0.6 wt% copper, 0.6 wt% indium, 5.2 wt% antimony, 0.06 wt% cobalt, and the remainder is tin along with unavoidable impurities. The melting range of this alloy is 221.6 to 229.7 °C. Example 42 - Alloy 56 (Reference example) Alloy 56 comprises 3.7 wt% silver, 1.1 wt% bismuth, 0.6 wt% copper, 4 wt% antimony, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 219.1 to 227.5 °C. This alloy has a hardness of 27.7 Hv. Example 43 - Alloy 57 (Reference example) Alloy 57 comprises 3.7 wt% silver, 2.1 wt% bismuth, 0.6 wt% copper, 3.9 wt% antimony, and the remainder is tin along with unavoidable impurities. The melting range of this alloy is 216.2 to 226.9 °C. The alloy has a hardness of 28.6 Hv. Example 44 - Alloy 58 (Reference example) Alloy 58 comprises 3.8 wt% silver, 3.2 wt% bismuth, 0.7 wt% copper, 3.6 wt% antimony, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 212.5 to 224.8 °C. The alloy's hardness is 30.8 Hv. Example 45 - Alloy 59 (Reference example) Alloy 59 comprises 3.5% by weight of silver, 4% by weight of bismuth, 0.6% by weight of copper, 3.6% by weight of antimony, and the balance is tin along with unavoidable impurities. The alloy has a melting range of 210.7 to 223.9 °C and a hardness of 30.8 Hv. Example 46 - Alloy 60 (Reference example) Alloy 60 comprises 3.1 wt% silver, 5.1 wt% bismuth, 0.5 wt% copper, 3.7 wt% antimony, and the remainder is tin along with unavoidable impurities. The melting range of this alloy is 209.5 to 222.7 °C and it has a hardness of 32.2 Hv. Example 47 - Alloy 61 (Reference example) Alloy 61 comprises 3.2 wt% silver, 6 wt% bismuth, 0.5 wt% copper, 3.2 wt% antimony, and the remainder is tin along with unavoidable impurities. This alloy has a melting range of 206.2 to 220.8 °C and a hardness of 32.2 Hv. A summary of the melting range of all alloys is presented in Table 1. Table 1: Melting range of the alloys q Lzznn / zznz / E / viAi Alloys Melting Range (°C) 96.5Sn3.OAgO.5Cu 216.6 - 219 1 215.4 - 221.9 201.5 - 228.5 1 202.8 - 217.9 2 209.7 - 223.5 3 203.3 - 236.1 4 197.4 - 231.6 7 211.4 - 225.5 8 215.2 - 228.3 9 186.9 - 232.9 10 202.5 - 232.5 11 214.3 - 228.4 12 213.9 - 230.4 13 195.3 - 229.3 14 186.5 - 232.5 15 198.9 - 230.9 17 198.9 - 227.6 18 202.6 - 229.2 19 203.3 - 229.7 20 203.8 - 226.5 22 210.8 - 224.5 23 202.9 - 224.6 24 195.8 - 228.6 25 194.5 - 220.3 26 217.5 - 227.1 27 212.8 - 224.5 29 209.9 - 221.2 31 222.6 - 232.3 32 214.4 - 225.6 34 195.1 - 211.8 36 208.9 - 221.9 37 209.6 - 224.9 38 210 - 225.3 39 213.9 - 224.6 40 214.7 - 224.6 41 215 - 225.7 42 213.8 - 228.5 43 221.9 - 229.3 45 221.6 - 229.7 46 197.5 - 209.3 47 200 - 211.3 48 203.7 - 211.9 49 218.4 - 222.5 q Lzznn / zznz / E / viAi 50 221.4 - 228.3 51 222.7 - 234.2 52 222.7 - 229.8 53 223.3 - 232.6 54 220.4 - 227.4 55 223.8 - 232.6 56 219.1 - 227.5 57 216.2 - 226.9 58 212.5 - 224.8 59 210.7 - 223.9 60 209.5 - 222.7 61 206.2 - 220.8 Figure 1 shows a micrograph of a welding alloy according to the present invention (Sn-5.3Sb3.8Ag-0.06Bi-0.6Cu-0.6In-0.06Ni). As can be seen, the welding alloy exhibits a microstructure showing an extensive AgaSn network. As described above, the distributed network of precipitate particles can resist grain boundary movement during creep deformation, thereby improving creep resistance. As discussed previously, reflow temperatures above 260 °C can cause several problems during soldering, such as damage to printed circuit boards and components. Figures 2 and 3 show the negative effects on the melting behavior of a Sn-Ag-Cu alloy when too much antimony or bismuth is added. As shown in Figure 2, increasing the antimony content from 1 to 8 wt% significantly increases the liquidus temperature, while the solidus temperature shows a gradual increase. In this example, when the antimony content is 7 wt% or less, the required reflow temperature will be 260 °C or less, considering that the peak reflow temperature is 25 to 30 °C above the liquidus temperature. The alloy that is the subject of Figure 2 contains 3.2-3.8 wt% Ag, 1-8 wt% Sb, 0.5-0.9 wt% Cu, the balance is Sn.In Figure 3, the antimony content is maintained between 3 and 4 wt%, while the bismuth content increases. The alloy shown in Figure 3 contains 3.2–3.8 wt% Ag, 3–4 wt% Sb, 1–6 wt% Bi, 0.5–0.7 wt% Cu, with Sn as the main component. In this example, when the bismuth content is 5 wt% or less, its solidus temperature remains above 210 °C, and the solidus-liquidus temperature difference is less than 10 °C. This is important because a lower solidus temperature can limit the operating temperature of the weld, and an excessively large solidus-liquidus temperature difference can lead to weld defects due to the soft zone formed before complete weld solidification. As can be seen in Figures 2 and 3, increasing antimony has a greater effect on increasing the liquidus temperature than on the solidus temperature (Figure 2).Decreasing antimony and increasing bismuth decrease the solidus and liquidus temperatures of the alloy (Figure 3). Solid solution strengthening and precipitation hardening caused by various alloying additions lead to increased hardness. For example, antimony contributes significantly to solid solution strengthening, while copper, with its very limited solubility in Cu-Sn intermetallics in tin forms, also increases alloy hardness. This effect is shown in Figure 4. Bismuth is also a well-known solid solution strengthening element for tin. The effect of increasing bismuth and slightly decreasing antimony on alloy hardness is shown in Figure 5. While increased hardness is often perceived as a negative and undesirable property of solder alloys due to the risk of increased brittleness, hardness can be transformed into a desirable property through balanced alloy design.In this way, hardness can contribute to improving the high thermomechanical properties of the alloys described in this document. Figure 6 shows the microstructures in the same state as cast, from left to right, alloys 4, 8, and 17. The (Cu,Ni)gSn5 precipitates are uniformly distributed in the AgsSn matrix and Sn grains (containing Bi and Sb). The white precipitates are those of Bi-Sn intermetallic particles that form when the solid solubility limit of bismuth in tin is exceeded. Figures 7 and 8 compare the room temperature tensile properties of several of the example alloys with those of 96.5Sn3.OAgO.5Cu. There is a notable increase in tensile strength compared to 96.5Sn3.OAgO.5Cu, between 66% and 144%. The results of a creep test provide important information about creep strength and creep deformation (elastic and plastic) over a relatively long period. In the case of high-temperature creep, the phenomenon of microstructure strengthening alternates with stress attenuation caused by microstructure annealing. The high-temperature creep properties of the alloys are presented graphically and compared with those of 96.5Sn3.OAgO.5Cu in Figures 9 and 10. The alloys of the present invention have a significantly higher creep strength, as indicated by the yield rupture time and the total yield plastic stress. A longer yield rupture time indicates higher creep strength. For example, at 150 °C, the yield rupture time of alloy 8 is 255% higher than that of 96.5Sn3.OAgO.5Cu. Diffusion-dependent creep strain depends on the homologous temperature, that is, the ratio of the test temperature to the material's melting point on an absolute scale. The homologous temperature of the welding alloy may be in the range of 0.84 to 0.86. Therefore, the melting point of the welding alloy does not have a significant effect on its mechanical properties. Table 2 compares the zero wetting time (To) of some of the example alloys with 96.5Sn3.OAgO.5Cu, which can be used as a measure of their weldability and wettability. The wetting properties of the alloys according to the present invention are comparable to those of the 96.5Sn3.OAgO.5Cu alloy. This is important because there is very often a degradation in the wetting properties of alloys with multiple alloying additions. The wetting tests were performed at 250 °C according to JIS Z 3198-4. q Lzznn / zznz / E / YiAi Table 2: Comparison of zero wetting time Intermetallic compounds due to alloy additions in these illustrative alloys resulted in additional strength in both the bulk alloy and the weld joint. Figures 11 and 12 show the results of thermal cycling performance tests. The thermal cycling was performed from -40 to 150 °C, with 30 minutes of dwell time at each temperature, in a test conducted according to IPC 9701A. Three key aspects of the post-thermal cycling test of the weld joints are the characteristic in-situ life, the extent of cracking in the weld joint, and the percentage of shear strength retained after the thermal cycling test. The characteristic thermal cycling life is given at a cumulative failure rate of 63.2% for BGA228 bundles when their electrical resistance is monitored in-situ using a high-speed data logger.According to IPC 9701A, a failure is defined as a 20% increase in electrical resistance measured over five consecutive readings. Figure 11 shows an example of how the total weld joint length is measured to calculate crack extent in BGAs. Crack extent is measured as a percentage of the total weld joint length. For illustrative purposes, the crack shown here starts near the weld-IMC interface and extends to 23% of the total weld joint length. Crack extent on each ball along the outermost row of weld joints in the BGA bundle was measured after 2500 cycles. An average crack extent was measured for each alloy and summarized in Table 3. q Lzznn / zznz / E / YiAi Table 3: Crack extension after 2500 thermal cycles Alloys Average crack extension in BGA228 (%) after 2500 thermal cycles 43.0 lb 32.0 Alloy 4 17.0 Alloy 8 7.0 Alloy 17 27.0 Alloy 22 23.0 Alloy 27 24.0 The shear strength retained after thermal aging at 150 °C for 2000 hours is calculated as a fraction of the initial shear strength obtained from chip resistors in the same state as when they were soldered. Table 4 shows results for some of these alloys, where the remaining shear strength is at least 85% of the shear strength of the original solder joint. Table 4: Shear strength retained after thermal aging of a 0805 q Lzznn / zznz / E / viAi chip resistor Alloys % shear strength retained after 2000 hours of thermal aging 95 lb 90 Alloy 4 88 Alloy 8 92 Alloy 17 96 Alloy 27 85 Figure 12 shows Weibull distribution plots of in-situ monitored BGA228 failures for a series of illustrative alloys according to the present invention. All the invented alloys have a longer characteristic life and a greater number of surviving components. During thermal cycling, the alloys are subjected to thermal stresses that lead to creep deformation. Alloys that can resist creep deformation or accumulate large deformations before fracture are expected to have higher thermal fatigue strength. The increased creep resistance of the invented alloys may result in higher thermal fatigue strength. The foregoing detailed description is provided for illustrative purposes only and is not intended to limit the scope of the appended claims. Many variations of the preferred embodiments currently illustrated herein will be obvious to a person skilled in the art and remain within the scope of the appended claims and their equivalents. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A lead-free solder alloy characterized in that it comprises: from 2.5 to 5% by weight of silver; from 0.01 to 5% by weight of bismuth; from 1 to 7% by weight of antimony; from 0.01 to 2% by weight of copper; one or more of: up to 6% by weight of indium, up to 0.5% by weight of titanium, up to 0.5% by weight of germanium, up to 0.5% by weight of rare earth elements, up to 0.5% by weight of cobalt, up to 5.0% by weight of aluminum, up to 5.0% by weight of silicon, up to 0.5% by weight of manganese, up to 0.5% by weight of chromium, up to 0.5% by weight of iron, up to 0.5% by weight of phosphorus, up to 0.5% by weight of gold, up to 1% by weight of... gallium by weight, up to 0.5% by weight of tellurium, up to 0.5% by weight of selenium, up to 0.5% by weight of calcium, up to 0.5% by weight of vanadium, up to 0.5% by weight of molybdenum, up to 0.5% by weight of platinum, and up to 0.5% by weight of magnesium; or Lzznn / zznz / E / viAi optionally up to 0.5% by weight of nickel; and the balance is tin together with any unavoidable impurities.

2. The welding alloy according to claim 1, characterized in that it comprises 2.8 to 4.5% by weight of silver, preferably 3 to 4% by weight of silver.

3. The welding alloy according to claim 1 or 2, characterized in that it comprises 1.0 to 4.0% by weight of bismuth, preferably 2.0 to 4.0% by weight of bismuth, more preferably 2.5 to 4% by weight of bismuth, even more preferably 2.8 to 4% by weight of bismuth, even more preferably 3 to 4% by weight of bismuth.

4. The welding alloy according to any of the preceding claims, characterized in that it comprises from 1.0 to 6.5% by weight of antimony, preferably from 2 to 6% by weight of antimony, more preferably from 3 to 6% by weight of antimony, even more preferably from 3.1 to 6% by weight of antimony, still more preferably from 3.2 to 6% by weight of antimony.

5. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.3 to 1.2% by weight of copper, and preferably from 0.4 to 0.8% by weight of copper.

6. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 0.4% by weight of nickel, preferably from 0.01 to 0.3% by weight of nickel, more preferably from 0.02 to 0.2% by weight of nickel.

7. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 5.5% by weight of indium, preferably from 0.02 to 4% by weight of indium, more preferably from 0.5 to 3% by weight of indium.

8. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 0.3% by weight of titanium, preferably from 0.005 to 0.2% by weight of titanium, more preferably from 0.007 to 0.05% by weight of titanium.

9. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 0.3% by weight of germanium, preferably from 0.001 to 0.1% by weight of germanium, more preferably from 0.001 to 0.02% by weight of germanium.

10. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.002 to 0.3% by weight of rare earths, preferably from 0.003 to 0.05% by weight of rare earths.

11. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.01 to 0.2% by weight of cobalt, preferably from 0.01 to 0.2% by weight of cobalt, more preferably from 0.02 to 0.1% by weight of cobalt.

12. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 3% by weight, preferably from 0.005 to 2% by weight of aluminum, more preferably from 0.01 to 1.5% by weight of aluminum, even more preferably from 0.015 to 1% by weight of aluminum, still more preferably from 0.02 to 0.08% by weight of aluminum.

13. The welding alloy according to any of the preceding claims, characterized in that it comprises from 0.001 to 3% by weight of silicon, preferably from 0.005 to 2% by weight of silicon, more preferably from 0.01 to 1.5% by weight of silicon, even more preferably from 0.015 to 1% by weight of silicon, still more preferably from 0.02 to 0.08% by weight of silicon.

14. The welding alloy according to any of the preceding claims, characterized in that it comprises one or more of: 0.001 to 0.5 wt% chromium, 0.01 to 0.5 wt% iron, 0.001 to 0.5 wt% phosphorus, 0.001 to 0.5 wt% gold, 0.2 to 0.8 wt% gallium, 0.001 to 0.5 wt% tellurium, 0.001 to 0.5 wt% selenium, 0.001 to 0.5 wt% calcium, 0.001 to 0.5 wt% vanadium, 0.001 to 0.5 wt% molybdenum, 0.001 to 0.5% by weight of platinum, and 0.001 to 0.5% by weight of magnesium.

15. The welding alloy according to any of the preceding claims, characterized in that it comprises one to three elements, preferably one or two elements, more preferably two elements selected from nickel, titanium, germanium, indium, manganese, rare earths, cobalt, aluminum, silicon, chromium, iron, phosphorus, gold, gallium, tellurium, selenium, calcium, vanadium, molybdenum, platinum and magnesium, preferably selected from nickel, titanium, germanium, indium, manganese, rare earths, cobalt, silicon, iron and gallium.

16. The welding alloy according to any of the preceding claims, characterized in that it comprises nickel and one of titanium, germanium, indium, manganese, rare earths, cobalt, aluminum, silicon, chromium, iron, phosphorus, gold, gallium, tellurium, selenium, calcium, vanadium, molybdenum, platinum and magnesium, preferably selected from nickel, titanium, germanium, indium, manganese, rare earths, cobalt, silicon, iron and gallium.

17. The welding alloy according to any of the preceding claims, characterized in that the weight percent of antimony is greater than the weight percent of bismuth.

18. The welding alloy according to any of the preceding claims, characterized in that the sum of the weight % of antimony and the weight % of bismuth is greater than or equal to 6.

5.

19. The welding alloy according to any preceding claim, characterized in that it consists of: 2.5 to 4% by weight of silver; 2.8 to 4.2% by weight of bismuth; 3.2 to 6.2% by weight of antimony; 0.4 to 0.8% by weight of copper; 0.04 to 0.18% by weight of nickel; and 0.007 to 0.05% by weight of titanium, 0.001 to 0.02% by weight of germanium, and 0.005 to 0.01% by weight of manganese; and the balance is tin together with any unavoidable impurities, wherein: the weight % of antimony is greater than the weight % of bismuth, and the sum of the weight % of antimony and the weight % of bismuth is greater than or equal to 6.

5.

20. The soldering alloy according to claim 1, characterized in that it comprises: 3 to 5% by weight of silver; 0.01 to 0.2% by weight of bismuth; 4 to 6% by weight of antimony; 0.3 to 1% by weight of copper; one or more of: up to 6% by weight of: indium, up to 0.5% by weight of titanium, up to 0.5% by weight of germanium, up to 0.5% by weight of rare earths, up to 0.5% by weight of cobalt, up to 5.0% by weight of aluminum, up to 5.0% by weight of silicon, up to 0.5% by weight of manganese, up to 0.5% by weight of chromium, up to 0.5% by weight of iron, up to 0.5% by weight of phosphorus, up to 0.5% by weight of gold, up to 1% by weight of: gallium, up to 0.5% by weight of tellurium, up to 0.5% by weight of selenium, up to 0.5% by weight of calcium, up to 0.5% by weight of vanadium, up to 0.5% by weight of molybdenum, up to 0.5% by weight of platinum, up to 0.5% by weight of magnesium; yq Lzznn / zznz / E / viAi the balance is tin along with any unavoidable impurities.

21. The soldering alloy according to claim 1, characterized in that it consists of 2.8 to 3.2% by weight of silver, 2.8 to 3.2% by weight of bismuth, 4.5 to 5.5% by weight of antimony, 0.3 to 0.8% by weight of copper, 0.08 to 0.2% by weight of nickel, 0.001 to 0.01% by weight of germanium, and the balance is tin together with unavoidable impurities.

22. The soldering alloy according to claim 1, characterized in that it consists of 2.8 to 3.2% by weight of silver, 2.8 to 3.2% by weight of bismuth, 5.5 to 6.5% by weight of antimony, 0.3 to 0.8% by weight of copper, 0.08 to 0.2% by weight of nickel, 0.005 to 0.02% by weight of titanium, and the balance is tin together with unavoidable impurities.

23. The soldering alloy according to claim 1, characterized in that it consists of 3.1 to 3.7% by weight of silver, 3 to 3.5% by weight of bismuth, 3 to 3.8% by weight of antimony, 0.4 to 0.9% by weight of copper, 0.01 to 0.9% by weight of nickel, 0.001 to 0.01% by weight of germanium, and the balance is tin together with unavoidable impurities.

24. The soldering alloy according to claim 1, characterized in that it consists of 3.2 to 3.9 wt% silver, 3.5 to 4.5 wt% bismuth, 5.5 to 6.5 wt% antimony, 0.3 to 0.9 wt% copper, 0.05 to 0.12 wt% nickel, 0.001 to 0.01 wt% manganese, and the balance is tin together with unavoidable impurities. (Alloy 4) 25. The soldering alloy according to claim 1, characterized in that it consists of 3.5 to 4.2% by weight of silver, 0.01 to 0.1% by weight of bismuth, 5 to 6% by weight of antimony, 0.4 to 0.9% by weight of copper, 0.001 to 0.01% by weight of germanium, 0.2 to 0.8% by weight of indium, 0.02 to 0.08% by weight of cobalt, and the balance is tin together with unavoidable impurities.

26. The soldering alloy according to any preceding claim, characterized in that it is in the form of a bar, rod, solid core or flux-cored wire, metal foil or strip, film, preform, powder or paste (powder plus flux mixture), soldering spheres for use in ball grid array joints, a preformed solder piece or a solidified or reflowed solder joint, pre-applied to any solderable material, such as copper tape for photovoltaic applications or a printed circuit board of any type.

27. A welded joint characterized in that it comprises the welding alloy in accordance with any of the preceding claims.

28. A soldering paste characterized in that it comprises: the soldering alloy according to any of claims 1 to 26, and a soldering flux.

29. A method for forming a solder joint, characterized in that it comprises: (i) providing two or more workpieces to be joined; (ii) providing a solder alloy according to any one of claims 1 to 26 or solder paste according to claim 28; and (iii) heating the solder alloy or solder paste in the adjacent area of ​​the workpieces to join them.

30. Use of a solder alloy according to any of claims 1 to 26, or solder paste according to claim 28 in a soldering method, preferably wherein the soldering method is selected from wave soldering, surface mount technology (SMT) soldering, die-fix soldering, thermal interface soldering, hand soldering, laser and RF induction soldering, soldering to a solar module, soldering of level 2 LED packaging boards, dip soldering, and rework soldering.

31. A method for manufacturing the welding alloy according to any of claims 1 to 26, characterized in that it comprises: providing the aforementioned elements, and melting the aforementioned elements, wherein the aforementioned elements may be provided in the form of individual elements and / or in the form of one or more alloys containing one or more of the aforementioned elements.