JP2008290150A - Tin / silver / copper / indium quaternary lead-free solder composition - Google Patents

Abstract

A suitable amount of indium (In) is added and the content of silver (Ag) is controlled so as to suppress a decrease in wettability due to a decrease in Ag content and to improve resistance to thermal cycling and mechanical shock. A quaternary lead-free solder composition of tin, silver, copper, and indium that optimizes and suppresses the cost rise of the lead-free solder composition and ensures sufficient processability and mechanical properties as a solder material. To provide.
SOLUTION: Silver (Ag) of 0.3 wt% or more and less than 2.5 wt%, Copper (Cu) of 0.2 wt% or more and less than 2.0 wt%, and Indium of 0.2 wt% or more and less than 1.0 wt%. It consists of (In) and other tin (Sn).
[Selection] Figure 8

Description

  The present invention relates to a lead-free solder (Pb-free) composition, and in particular, tin (Sn) / silver (Ag) / copper (Cu) / indium (In) in which the amount of silver used is reduced by using indium. The present invention relates to a quaternary lead-free solder composition.

  At present, in the case of a lead-free solder composition, the Sn—Ag—Cu system is most commonly used, and a representative composition includes a Sn—3.0Ag—0.5Cu composition. In addition, in order to improve the oxidation resistance of such a composition, P, Ge, Ga, Al, Si, etc. may be further added in the range of several tens of ppm to several thousand ppm, respectively. And Ni, Co, Fe, Bi, Au, Pt, Pb, Mn, V, Ti, Cr, Nb, Pd, Sb, Mg, Ta, Cd, and rare earths (rare earth) ) Metals and the like may be further added in the range of several tens of ppm to several thousand ppm.

  However, in recent years, as efforts for cost reduction have been expanded mainly in the field of electronic packaging, research to reduce the amount of the most expensive Ag element among additive elements has been attempted. The Sn-2.5Ag-0.5Cu composition and the Sn-1.0Ag-0.5Cu composition are applied, and recently, the characteristics of the Sn-0.3Ag-0.5Cu composition have been evaluated. .

  In Sn-Ag-Cu series solder, changes in metallographic and mechanical properties depending on the amount of Ag are summarized as follows.

1) As the added amount of Ag decreases, the difference between the liquidus temperature and the solidus temperature increases, and the solid-liquid coexistence region (passy range or mush zone) increases.
2) As the amount of Ag added decreases, wettability decreases depending on the result of 1).
3) The strength and creep resistance of the alloy decrease as the Ag addition amount decreases.
4) As the Ag addition amount decreases, the fracture rate of the solder joint by the thermal cycle experiment increases according to the result of 3).
5) As the amount of Ag added decreases, the stretch ratio of the alloy increases and the breaking speed of the solder joint by the mechanical impact experiment decreases.

Therefore, since the case 1) corresponds to the phenomenon of metallurgical property change due to the Ag content in the solder, when the Ag content is decreased, an appropriate Ag amount is set, while the conventional Sn-3. Only when the wettability close to the 0Ag-0.5Cu composition is ensured, the application as a solder material becomes smooth, and the ultimate cost can be reduced by reducing the Ag content.
In the case of the above 4) and 5), it can be said that the opposite characteristics are exhibited due to the decrease in the Ag content of the solder. Only when the improvement is complemented can an ideal solder composition be designed that can simultaneously ensure resistance to thermal cycling and mechanical shock, and further to reduce costs by reducing Ag content.

  However, the actual situation is that a lead-free solder composition satisfying the above conditions has not yet been developed.

  The present invention has been proposed to solve the above-described problems of the prior art, and its purpose is to suppress a decrease in wettability due to a decrease in Ag content, and to improve resistance to thermal cycling and mechanical shock. In order to be able to improve, by adding an appropriate amount of indium (In) and optimizing the content of silver (Ag), the cost increase of the lead-free solder composition is suppressed, and the processability and machine as a solder material It is an object of the present invention to provide a ternary lead-free solder composition of tin, silver, copper, and indium that can sufficiently ensure the desired characteristics.

Therefore, the present invention for achieving the above-described object includes a silver (Ag) of 0.3 wt% or more and less than 2.5 wt%, a copper (Cu) of 0.2 wt% or more and less than 2.0 wt%, It comprises a quaternary lead-free solder composition of tin, silver, copper, and indium, characterized by comprising indium (In) of 2 wt% or more and less than 1.0 wt% and other tin (Sn). And
In the lead-free solder composition having the above-described characteristics, in order to reduce the cost of the lead-free solder composition, a decrease in wettability caused by a decrease in the amount of silver added, a thermal cycle and a mechanical shock. By complementing the insufficient reliability through the addition of indium (In), it is possible to provide a lead-free solder composition of superior quality at a lower price.

  According to the present invention, the content of silver (Ag) is reduced, and the wettability due to the reduction of silver (Ag) is supplemented by adding indium (In), thereby improving the resistance to thermal cycle and mechanical impact. Therefore, it is possible to provide an excellent quality lead-free solder composition at a low cost.

  Hereinafter, the features of the present invention will be described in detail through preferred embodiments of the present invention. In the description of the present invention, when it is determined that a specific description related to a known related function or configuration may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted.

  In the lead-free solder composition of the present invention, the addition ratio of silver (Ag) is 0.3 wt% or more and less than 2.5 wt%. This is because when silver (Ag) is added at less than 0.3 wt%, the drop in liquidus temperature hardly progresses and the melting point of the solder and the mounting process temperature increase. When (Ag) is added, there is a disadvantage that the cost reduction required by the present invention is hindered. Therefore, the addition ratio of silver (Ag) is 0.3 wt% or more and less than 2.5 wt%, and desirably 1.2 wt%.

In the lead-free solder composition of the present invention, the addition ratio of copper (Cu) is 0.2 wt% or more and less than 2.0 wt%. This is because, when copper (Cu) is added at less than 0.2 wt%, the drop in liquidus temperature is small, there is almost no fraction of Cu ₆ Sn ₅ phase, and the strength of the solder alloy is reduced. When copper (Cu) is added at 2.0 wt% or more, the difference between the liquidus temperature and the solidus temperature increases and the solid-liquid coexistence region increases, and Cu ₆ Sn ₅ There are disadvantages in that the phase fraction is increased to greatly increase the mechanical properties of the solder alloy and increase the growth rate of the interface reaction layer. Therefore, the addition ratio of copper (Cu) is 0.2 wt% or more and less than 2.0 wt%, and desirably 0.5 wt%.

In the lead-free solder composition of the present invention, the addition ratio of indium (In) is 0.2 wt% or more and less than 1.0 wt%. This is because when indium (In) is added at less than 0.2 wt%, the improvement in wettability and the improvement in mechanical properties due to the addition of In are very small. ), The improvement of wettability and mechanical properties do not increase in proportion to the amount of indium (In) added, while the price of the solder alloy increases rapidly. Therefore, the addition ratio of indium (In) is 0.2 wt% or more and less than 1.0 wt%, and more preferably 0.4 wt%.
On the other hand, according to the preferable addition ratio of each additive element, the most ideal lead-free solder composition is Sn-1.2Ag-0.5Cu-0.4In, which is the most ideal composition of the present invention. Sn-1.2Ag-0.5Cu-0.4In, various other research compositions, and conventional research compositions Sn-3.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu, Sn The results of evaluating the -1.2Ag-0.5Cu-0.05Ni composition through the same experimental process are shown in FIGS.

  1 and 2 show the results showing an endothermic peak due to the solder composition in the heated state. The results of FIGS. 1 and 2 show that a differential scanning calorimeter (DSC) is used to heat about 8 mg of a solder alloy at a rate of temperature increase of 10 ° C./min in a nitrogen flow atmosphere of 50 ml / min. It is the result of measuring the endothermic peak generated when As shown in FIG. 1, the Sn-3.0Ag-0.5Cu composition shows an endothermic peak temperature in the range of 217 ° C. to 218 ° C., which is consistent with the melting point of this alloy. . On the other hand, in the case of Sn-1.0Ag-0.5Cu composition, a primary endothermic peak in the range of 218 ° C to 219 ° C and a secondary endothermic peak at 226 ° C are shown, and the liquidus temperature and the solidus line, respectively. Observed as temperature, it can be seen that the solid-liquid coexistence region is greatly increased. In the case of Sn-1.2Ag-0.5Cu-0.05Ni composition, a primary endothermic peak in the range of 219 ° C. to 220 ° C. and a secondary endothermic peak in the range of 225 ° C. to 226 ° C. are shown, respectively. Observed as the temperature and the solidus temperature, it can be observed that the solid-liquid coexistence region is greatly increased.

  On the other hand, as shown in FIG. 2, in the case of Sn-1.0Ag-0.5Cu-1.0In composition, a primary endothermic peak is shown at 216 ° C., and a secondary endothermic peak is shown in the range of 224 ° C. to 225 ° C. It was observed as the liquidus temperature and the solidus temperature, respectively, and the solid-liquid coexistence region was also greatly increased, but it can be seen that the liquidus temperature and the solidus temperature are somewhat lowered. It can be seen that the result of such a low-temperature transition between the liquidus temperature and the solidus temperature is the main cause of the excellent effect of solder wettability at low temperatures. In the case of Sn-1.0Ag-0.5Cu-0.5In composition, a primary endothermic peak is shown at 217 ° C., and a secondary endothermic peak is shown at 225 ° C., which are observed as liquidus temperature and solidus temperature, respectively. Again, it can be seen that the solid-liquid coexistence region has greatly increased, but the liquidus temperature and the solidus temperature are somewhat lowered as a whole.

  In the case of Sn-1.2Ag-0.5Cu-0.8-0.4In composition, the primary endothermic peak is in the range of 217 ° C to 218 ° C, and the secondary endothermic peak is in the range of 224 ° C to 225 ° C. It was observed as liquidus temperature and solidus temperature, respectively, and the solid-liquid coexistence region was greatly increased, but again the liquidus temperature and the solidus temperature were somewhat lowered overall I understand. However, in the case of the Sn-1.2Ag-0.5Cu-0.2In composition, a primary endothermic peak is shown in the range of 219 ° C to 220 ° C, and a secondary endothermic peak is shown at 226 ° C. The solid-liquid coexistence region was greatly increased, but the liquidus temperature and the solidus temperature were not lowered compared to the Sn-1.0Ag-0.5Cu composition. I understand that. Such a result shows that, in the case of the Sn-1.2Ag-0.5Cu-0.2In composition, the solder wettability at a low temperature is not greatly improved as compared with the Sn-1.0Ag-0.5Cu composition. It turns out that it is a cause.

  FIG. 3 and FIG. 4 show the results showing the primary heat generation peak due to the solder composition in the cooled state after melting. The results of FIGS. 3 and 4 are also generated when approximately 8 mg of solder alloy is heated to 250 ° C. at a rate of 10 ° C./min in a nitrogen flow atmosphere of 50 ml / min using a differential scanning calorimeter and then cooled. It is the result of measuring a primary endothermic peak. As shown in FIG. 3, the Sn-3.0Ag-0.5Cu composition shows a first exothermic peak of about 194 ° C., which indicates the actual solidification temperature of this alloy. . Metallographically, the difference between the melting temperature of the alloy and the actual solidification temperature, i.e., in this case, the difference between about 23 ° C and 24 ° C is referred to as undercooling or supercooling. Depending on the Ag content in the alloy, the magnitude of such undercooling will increase. As an example, the Sn-1.0Ag-0.5Cu composition shows a primary exothermic peak of about 188 ° C., Shown that undercooling is increasing. On the other hand, in the case of Sn-1.2Ag-0.5Cu-0.05Ni composition, a primary exothermic peak in the range of about 206 ° C to 207 ° C is exhibited, and the addition of a small amount of Ni greatly reduces the undercooling. I understand.

  The result when indium (In) is added is as shown in FIG. In the case of the Sn-1.0Ag-0.5Cu-1.0In composition, a primary exothermic peak of about 200 ° C. is observed, and in the case of the Sn-1.0Ag-0.5Cu-0.5In composition, about 190 ° C. A primary exothermic peak in the range of from 0C to 191C was observed. Therefore, indium (In) was also analyzed as an element that greatly reduces undercooling. Further, in the case of the Sn-1.2Ag-0.5Cu-0.8In composition, the primary exothermic peak in the range of about 192 ° C to 193 ° C has the Sn-1.2Ag-0.5Cu-0.6In composition. In the case of the Sn-1.2Ag-0.5Cu-0.4In composition, the primary exothermic peak in the range of about 200 ° C to 201 ° C is obtained. In the case of Sn-1.2Ag-0.5Cu-0.2In composition, a primary exothermic peak in the range of about 202 ° C to 203 ° C was observed.

  5 and 6 show zero cross time values depending on the soldering temperature. One wettability test can measure a zero cross time value, a wetting force after 2 seconds (wetting force at 2 seconds), a final wetting force (final wetting force), etc. at a time. The result of averaging the test values of the test times or more is shown. The specimen used for the wettability test is a Cu piece having a width of 3 mm and a length of 10 mm. After applying a water-soluble type flux of Senju Co., Ltd. to the surface of the Cu piece, The molten solder was charged, and the charging depth was 2 mm. The charging speed and the detaching speed of the Cu piece were 5 mm / sec, respectively. As shown in FIG. 5, in the case of Sn-1.2Ag-0.5Cu-0.05Ni composition and Sn-1.0Ag-0.5Cu composition, compared with the Sn-3.0Ag-0.5Cu composition, A large zero cross time value was measured, particularly a further increase in the zero cross time value at low temperatures in the range of 230 ° C to 240 ° C. On the other hand, when indium (In) is added as shown in FIG. 6, a significant decrease in the zero cross time value is observed, and a more effective decrease in the zero cross time value is observed at a low temperature in the range of 230 ° C. to 240 ° C. Measured. In particular, in the case of the Sn-1.2Ag-0.5Cu-0.4In composition which is a representative composition according to the present invention, a zero cross time value similar to or slightly superior to the Sn-3.0Ag-0.5Cu composition is shown. It can be confirmed that the solder material has very good wetting characteristics.

  7 and 8 show changes in the wetting force after 2 seconds depending on the soldering temperature. As shown in FIG. 7, in the case of Sn-1.0Ag-0.5Cu composition and Sn-1.2Ag-0.5Cu-0.05Ni composition, 2 seconds later than Sn-3.0Ag-0.5Cu. A very small wetting force was measured, and the wetting force after 2 seconds was further significantly reduced, particularly at a low temperature in the range of 230 ° C to 240 ° C. On the other hand, when indium (In) is added as shown in FIG. 8, a remarkable increase in the wetting force after 2 seconds is observed, and the wetting force after 2 seconds at a low temperature in the range of 230 ° C. to 240 ° C. It was found to increase more effectively. In particular, in the case of the Sn-1.2Ag-0.5Cu-0.4In composition which is a representative composition of the present invention, it has a wetting force after 2 seconds which is similar to or slightly better than Sn-3.0Ag-0.5Cu. Can be confirmed.

  When looking at the results as described above, the composition of the present invention exhibits excellent wettability characteristics despite the fact that the alloy price is very low, and possesses characteristics that are very suitable as a soldering material. I understand that. Therefore, the lead-free solder composition of the present invention comprises a solder paste, solder ball, solder bar, solder wire, solder bump, solder thin plate, solder powder, solder pellet, solder particle, solder ribbon, solder washer, solder ring, and It can be applied to the manufacture of a solder preform such as a solder disk.

  9 and 10 show changes in the final wetting force depending on the soldering temperature. As shown in FIG. 9, in the case of the Sn-1.0Ag-0.5Cu composition and the Sn-1.2Ag-0.5Cu-0.05Ni composition, the final composition compared to the Sn-3.0Ag-0.5Cu composition. The wettability was very small, and the final wettability was further reduced particularly at low temperatures in the range of 230 ° C to 240 ° C. On the other hand, as shown in FIG. 10, when indium (In) was added, an interesting result was observed, but when the composition of Sn-1.2Ag-0.5Cu-xIn was used as a reference, indium (In) When the amount is as large as 0.8 wt%, the final wettability improvement is small due to the low surface tension value of molten indium (In), and the amount of indium (In) is as small as 0.2 wt% In the case of the Sn-1.2Ag-0.5Cu-0.4In composition, which is a representative composition of the present invention, the improvement of the wetting force was slight and the final wetting force was not improved. It can be confirmed that the final wettability is similar to or slightly worse than the 0Ag-0.5Cu composition. In particular, the Sn-1.2Ag-0.5Cu-0.4In composition has a very good final wettability at a low temperature in the range of 230 ° C. to 240 ° C. compared to other low Ag-containing compositions. Can be confirmed.

  FIG. 11 shows a conventional Sn-3.0Ag-0.5Cu composition, Sn-1.0Ag-0.5Cu composition, and Sn-1.2Ag-0.5Cu-0.05Ni composition as tensile test pieces. The results of testing are shown. The tensile test piece was a proportional tensile test piece according to KS standard 13A, the thickness was 2 mm, the length was 27 mm, the tensile test temperature was room temperature, and the tensile test speed was 7.8 mm / min. As shown in the figure, in the case of Sn-3.0Ag-0.5Cu composition, the strength is high, but the stretch ratio is very small, and when used as a solder joint material, the resistance to thermal cycling is excellent, Resistance to mechanical impact is expected to represent very poor properties. On the other hand, in the case of Sn-1.0Ag-0.5Cu composition, the stretch ratio increases somewhat, but the strength is very small, and the resistance to mechanical impact is higher than that of Sn-3.0Ag-0.5Cu composition. Although relatively improved, resistance to thermal cycling is expected to represent poor properties. Further, in the case of the Sn-1.2Ag-0.5Cu-0.05Ni composition, the two compositions mentioned above, that is, an intermediate between Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu It was possible to observe the expression of the mechanical characteristics.

FIG. 12 shows the Sn-1.2Ag-0.5Cu-0.4In composition, which is a representative composition of the present invention, and other Sn-1.2Ag-0.5Cu-0.2In and Sn-1.2Ag-0. .5Cu-0.6In, Sn-1.2Ag-0.5Cu-0.8In, Sn-1.0Ag-0.5Cu-1.0In composition as tensile test pieces and the results of testing Show. In the case of Sn-1.2Ag-0.5Cu-0.4In, the strength is greatly improved as compared with Sn-1.0Ag-0.5Cu which is a similar composition, and the stretch ratio is also greatly improved. In particular, it can be seen that the toughness of the alloy has been greatly improved. Such characteristics represent the best resistance to mechanical impact and are also expected to be relatively resistant to thermal cycling, especially mobile products that are susceptible to mechanical shock or vibration, It is expected to be a solder composition that is very suitable as a bonding material for electronics inside automobiles. In the case of Sn-1.2Ag-0.5Cu-0.2In, the strengthening phenomenon of the metal due to the addition of indium (In) is reduced and the strength value is decreased, and Sn-1.2Ag-0.5Cu-0. In the case of 6In and Sn-1.2Ag-0.5Cu-0.8In, a phenomenon in which the stretch ratio gradually decreased with an increase in the amount of indium (In) added. In the case of Sn-1.0Ag-0.5Cu-1.0In, although the amount of indium (In) added was large, an excellent strength value was not exhibited.
In addition, another example of Sn-Ag-Cu-In quaternary lead-free solder composition according to the present invention is Sn-0.3Ag-0.7Cu-0.2In composition and conventional Sn-3.0Ag. The results of evaluating the wetting characteristics through the same test process described above for the -0.5Cu, Sn-1.0Ag-0.5Cu, and Sn-0.3Ag-0.7Cu compositions are shown in FIGS. ing.

  FIG. 13 shows the change in the zero cross time value due to the soldering temperature, FIG. 14 shows the change in the wetting force after 2 seconds due to the soldering temperature, and FIG. 15 shows the change in the final wetting force due to the soldering temperature. Show. As shown in FIGS. 13 to 15, the Sn-0.3Ag-0.7Cu-0.2In composition to which a small amount of indium (In) is added is particularly compared with the Sn-0.3Ag-0.7Cu composition. It can be seen that the above-mentioned various wettability characteristics are greatly improved at a temperature of 240 ° C. or higher, and show a value almost similar to the Sn-1.0Ag-0.5Cu composition. As a result, the quaternary lead-free solder composition of tin, silver, copper, and indium according to the present invention minimizes the increase in cost by adding a small amount of indium, and improves the wettability by reducing the silver content. It can further be confirmed that the reduction can be suppressed.

Meanwhile, in order to improve the oxidation resistance of the Sn—Ag—Cu—In quaternary lead-free solder composition according to the present invention, phosphorus (P), germanium (Ge), gallium (Ga), aluminum (Al ) And one or more elements selected from silicon (Si) can be mixed and further added in the range of 0.001 wt% to 1 wt%.
In addition, it is selected from zinc (Zn) and arsenic (Bi) in order to improve the interfacial reaction characteristics and lower the melting point of the Sn—Ag—Cu—In quaternary lead-free solder composition according to the present invention. One element or two elements formed can be mixed and further added in the range of 0.001 wt% to 2 wt%.

In order to improve the mechanical characteristics and interfacial reaction characteristics of the Sn-Ag-Cu-In quaternary lead-free solder composition according to the present invention, nickel (Ni), cobalt (Co), iron (Fe) , Gold (Au), platinum (Pt), lead (Pb), manganese (Mn), vanadium (V), titanium (Ti), chromium (Cr), niobium (Nb), palladium (Pd), antimony (Sb) , Magnesium (Mg), tantalum (Ta), cadmium (Cd), and one or more elements selected from rare earth (Rare Earth) metals may be mixed to form 0.001 wt% to 1 wt% Further additions can be made within the range.
In order to avoid the patent of the Sn-Ag-Cu-In quaternary lead-free solder composition according to the present invention, the above-mentioned supplementary notes are Sn-Ag-Cu-In quaternary lead-free solder composition. This is to convey that the method of adding a trace amount of one or more elements to the above is also a technical field belonging to the present invention.

  As described above, the present invention reduces the content of silver (Ag), and supplements the wettability due to the reduction of silver (Ag) by adding indium (In), thereby preventing thermal cycle and mechanical impact. It has become possible to provide a lead-free solder composition with improved quality and excellent quality at a low cost.

  The present invention is not limited to the specific preferred embodiments described above, but has a general knowledge in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Anyone can make various modifications, and such changes are within the scope of the claims.

It is the result which showed the endothermic peak by the conventional solder composition in a heating state. It is the result which showed the endothermic peak by the solder composition of this invention in a heating state. It is the result which showed the exothermic peak by the conventional solder composition in the cooling state after melting. It is the result which showed the exothermic peak by the solder composition of this invention in the cooling state after melting. It is the graph which showed the zero crossing time value by the soldering temperature in the conventional solder composition. 4 is a graph showing a zero cross time value depending on a soldering temperature in the solder composition of the present invention. It is the graph which showed the change of the wetting force after 2 second by soldering temperature in the conventional solder composition. In the solder composition of this invention, it is the graph which showed the change of the wetting force after 2 second by soldering temperature. It is the graph which showed the change of the final wettability with soldering temperature in the conventional solder composition. 5 is a graph showing a change in final wetting force depending on a soldering temperature in the solder composition of the present invention. Results of manufacturing and testing conventional Sn-3.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu, Sn-1.2Ag-0.5Cu-0.05Ni solder compositions as tensile test pieces It is the graph which showed. In the solder composition of the present invention, Sn-1.2Ag-0.5Cu-0.4In and Sn-1.2Ag-0.5Cu-0.2In, Sn-1.2Ag-0.5Cu-0.6In, Sn It is the graph which showed the result of having manufactured and tested the -1.2Ag-0.5Cu-0.8In and Sn-1.0Ag-0.5Cu-1.0In composition as a tensile test piece. The Sn-0.3Ag-0.7Cu-0.2In composition of the present invention is made up of conventional Sn-3.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu, Sn-0.3Ag-0.7Cu. It is the graph which showed the change of the zero crossing time value by the soldering temperature compared with the composition. The Sn-0.3Ag-0.7Cu-0.2In composition of the present invention is made up of conventional Sn-3.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu, Sn-0.3Ag-0.7Cu. It is the graph which showed the change of the wetting force after 2 seconds by the soldering temperature compared with the composition. The Sn-0.3Ag-0.7Cu-0.2In composition of the present invention is made up of conventional Sn-3.0Ag-0.5Cu, Sn-1.0Ag-0.5Cu, Sn-0.3Ag-0.7Cu. It is the graph which showed the change of the final wetting power by the soldering temperature compared with the composition.

Claims (4)

  0.3 wt% or more and less than 2.5 wt% silver (Ag), 0.2 wt% or more and less than 2.0 wt% copper (Cu), 0.2 wt% or more and less than 1.0 wt% indium (In) A quaternary lead-free solder composition of tin, silver, copper, and indium, characterized by comprising other tin (Sn).   One or more selected from phosphorus (P), germanium (Ge), gallium (Ga), aluminum (Al), and silicon (Si) in order to improve the oxidation resistance of the lead-free solder composition; The quaternary lead-free solder composition of tin, silver, copper, and indium according to claim 1, wherein two or more elements are mixed and further added in a range of 0.001 wt% to 1 wt%. .   One or two elements selected from zinc (Zn) and arsenic (Bi) are mixed in order to improve the interfacial reaction characteristics and lower the melting point of the lead-free solder composition. The quaternary lead-free solder composition of tin, silver, copper, and indium according to claim 1, further added in a range of 2 wt%.   To the lead-free solder composition, nickel (Ni), cobalt (Co), iron (Fe), gold (Au), platinum (Pt), lead (Pb), manganese (Mn), vanadium (V), titanium ( Ti), chromium (Cr), niobium (Nb), palladium (Pd), antimony (Sb), magnesium (Mg), tantalum (Ta), cadmium (Cd), and rare earth (Rare Earth) metals 2. A quaternary lead of tin, silver, copper, and indium according to claim 1, wherein one or more elements are mixed and further added in a range of 0.001 wt% to 1 wt%. Free solder composition.

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