Multi-component tin-indium system lead-free low-temperature solder and preparation method thereof

Abstract

The invention discloses a multi-component tin-indium lead-free low-temperature solder and a preparation method thereof, and belongs to the technical field of microelectronic packaging. The multi-component tin-indium system lead-free low-temperature solder comprises the following components in percentage by mass: 0.5 to 5 percent of Bi, 0.1 to 1.5 percent of Ga, and the balance of Sn25In matrix and a small amount of inevitable impurities. Compared with a traditional solder, the multi-component tin-indium system lead-free low-temperature solder has the advantages of being good in heat conduction performance, good in mobility, small in expansion and shrinkage rate, environmentally friendly, safe and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of microelectronic packaging, and particularly relates to a multi-component tin-indium-based lead-free low-temperature solder and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for low-cost and low-temperature soldering processes in the field of electronic packaging, the currently developed low-temperature solders include pure indium and pure tin solders. Among them, the pure indium solder has excellent performance, but the price of indium metal is high, and the cost is very high, so there is basically no pure indium solder product on the market; the melting point of the pure tin solder is about 232℃, but the pouring temperature reaches about 350℃, which cannot be normally applied in a low-temperature welding environment.

[0003] Lead-free low-temperature solder alloys have rapidly developed in recent years due to environmental protection requirements and the trend of miniaturization of electronic equipment. The core advantage is the low-temperature welding characteristic, which can reduce the damage to heat-sensitive components and reduce energy consumption. Commonly used lead-free low-temperature solder alloys include tin-bismuth and tin-indium systems. The tin-bismuth alloy has been scaled in the notebook computer motherboard field due to its low melting point; and the tin-indium alloy has a lower melting point and better wetting performance, and is suitable for biological medical and aviation low-temperature packaging fields, but the melting point and performance of the tin-indium alloy are related to the proportion of indium in the alloy, and the high indium content leads to high cost.

[0004] Chinese patent CN202411113336.9 proposes a full-IMC phase Sn-Bi-In-Ag-Zn high-entropy low-temperature solder for chip interconnection and a preparation method thereof. The steps of the preparation method include: (1) weighing high-purity Sn, In, Bi, and Ag particles according to the designed proportion, and covering them with 1.3:1 KCl and LiCl molten eutectic salt protection, smelting Sn-In-Bi-Ag four-element intermediate alloy, and sequentially placing Sn, In, Bi, and Ag in the order of low-density metal first and high-density metal last to reduce specific gravity segregation during smelting, and directly pouring into water for cooling after 2h of 850℃ holding and sufficient stirring; (2) weighing high-purity Zn particles and Sn-In-Bi-Ag four-element intermediate alloy according to the designed proportion, and placing the Sn-In-Bi-Ag four-element intermediate alloy on the Zn particles to play a protective role, pouring the molten KCl and LiCl eutectic salt on the surface of the metal raw material, and directly pouring into water for cooling after 1h of 500℃ holding and sufficient stirring to obtain Sn-Bi-In-Ag-Zn high-entropy alloy solder. However, the In element accounts for more than 25% in the solder obtained by the preparation method, and other noble metals are added, so the cost is still high.

[0005] In summary, it is an urgent problem in the technical field to develop a lead-free, environmentally friendly, low-cost, and low-temperature solder with welding performance comparable to that of high-indium-content alloy. SUMMARY

[0006] In order to solve the above technical problems, the application provides a multi-component tin-indium lead-free low-temperature solder and a preparation method thereof.

[0007] To achieve the above object, the application provides the following technical scheme.

[0008] One of the objects of the application is to provide a multi-component tin-indium lead-free low-temperature solder, which comprises the following components in percentage by mass: Bi: 0.5-5%, Ga: 0.1-1.5%, and the rest is Sn25In matrix and an unavoidable small amount of impurities.

[0009] The multi-component lead-free low-temperature solder provided by the application is mainly tin-indium alloy. The melting point of In element is only 156.61℃, and the solder alloy has good thermal and electrical conductivity, good fluidity, low expansion rate and other characteristics. The addition of In element to the solder alloy can reduce the melting point, and the solder is lead-free and non-toxic, and environmentally friendly. The solder also adds Bi element and Ga element. The Bi element can reduce the melting point of the solder alloy, and the Bi also has the characteristics of solidification expansion, which can offset the stress generated by thermal expansion and cold shrinkage during welding, and reduce the risk of cracking of the solder joint. However, if the content of Bi exceeds 7.5%, the solder joint will be filled with a raised or cracked phenomenon. The Ga element has an ultra-low melting point of only 29.76℃, and the Ga also has excellent wettability and fluidity, which can increase the soldering spread area of the solder alloy by 15-20%, and reduce the risk of false welding.

[0010] Further, the multi-component tin-indium lead-free low-temperature solder comprises the following components in percentage by mass: Bi: 0.99-2%, Ga: 0.1-1%, and the rest is Sn25In matrix and an unavoidable small amount of impurities.

[0011] Further, the multi-component tin-indium lead-free low-temperature solder comprises the following components in percentage by mass: Bi: 0.99-2%, Ga: 0.1-1%, and the rest is Sn25In matrix and an unavoidable small amount of impurities.

[0012] Further, in the Sn25In matrix, the mass ratio of Sn and In is (72.75-74.18):(24.25-24.73).

[0013] The second object of the application is to provide a preparation method of a multi-component tin-indium lead-free low-temperature solder, which comprises the following steps:

[0014] Preparation of Sn25In matrix;

[0015] The Bi, Ga and Sn25In matrix are weighed and mixed to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, an antioxidant is added, and the second heating is carried out under a nitrogen atmosphere until the material is melted, and the second constant temperature stirring is carried out, and the multi-component tin indium system lead-free low-temperature solder is obtained by pouring into a mold.

[0016] Further, the preparation method of the Sn25In matrix comprises the following steps: Sn raw material is added into a lead-free graphite heating furnace for first heating until the material is melted, then In raw material is added, and heating is continued until melting, and first constant temperature stirring is carried out to obtain the Sn25In matrix.

[0017] Further, the temperature of the first heating is 300-350℃; and / or,

[0018] The specific operation steps of the first constant temperature stirring are: stirring at 300-350℃ for 30 minutes.

[0019] Further, the antioxidant is added in an amount that can fully cover the surface; and the antioxidant is rosin.

[0020] Further, the temperature of the second heating is 300-350℃; and / or,

[0021] The specific operation steps of the second constant temperature stirring are: stirring at 300-350℃ for 30 minutes and then keeping warm for 30 minutes to mix the multiple elements uniformly.

[0022] Further, the material of the mold is graphite.

[0023] The third object of the present application is to provide an application of the multi-component tin indium system lead-free low-temperature solder in the field of microelectronic packaging low-temperature welding.

[0024] Compared with the prior art, the present application has the following advantages and technical effects:

[0025] 1. Inhibit low-temperature phase transition and prevent "tin epidemic": Tin is prone to allotropy transformation (beta tin→alpha tin) in low-temperature environment, i.e. "tin epidemic", which can cause material pulverization failure. The addition of bismuth can effectively inhibit this phenomenon and improve the low-temperature stability of the solder, so that it still maintains structural integrity in a low-temperature environment. This characteristic is particularly important for electronic devices that need to work in a low-temperature environment for a long time.

[0026] 2. Enhance oxidation resistance and welding quality: The addition of bismuth and gallium can reduce the oxidation tendency of the solder and significantly improve the oxidation resistance of the solder; if further adding nano-particles in the solder, the mechanical properties caused by the addition of gallium can be compensated, so that the solder becomes a lead-free low-temperature solder with excellent low-temperature characteristics, wetting performance, mechanical properties and other performances.

[0027] 3. Optimizing mechanical properties and reliability: The addition of bismuth can improve the ductility and fatigue resistance of the alloy, while the liquid wetting properties of gallium help to form a more uniform weld structure. After adding bismuth, the solder will form a fine-grained structure during solidification, thereby reducing the tendency of cracking and improving joint strength. In addition, the flowability of gallium can also enhance the coverage of solder on complex surfaces, enhancing the reliability of welding.

[0028] 4. Expanding application scenarios: Bismuth and gallium-containing tin-indium-based solders are not only suitable for traditional electronic packaging, but also can be used for special welding in low-temperature environments (such as aerospace equipment), high-precision sputtering target binding, and connection of heat-sensitive components.

[0029] 5. Low cost: The solder formulation of the present application significantly reduces the amount of metal In compared to traditional tin-indium-based solder formulations, thereby achieving low cost. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The illustrations are shown to explain the present application and are not intended to limit the present application in an inappropriate manner. In the drawings:

[0031] Figure 1 Melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared for Example 1 of the present application;

[0032] Figure 2 Melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared for Example 2 of the present application;

[0033] Figure 3 Melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared for Example 3 of the present application;

[0034] Figure 4 Melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared for Example 4 of the present application;

[0035] Figure 5 Melting characteristic curve of the solder prepared for Comparative Example 1 of the present application;

[0036] Figure 6 Melting characteristic curve of the solder prepared for Comparative Example 2 of the present application;

[0037] Figure 7 Melting characteristic curve of the solder prepared for Comparative Example 3 of the present application;

[0038] Figure 8 Comparison chart of tensile strength of the solder prepared for Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 of the present application;

[0039] Figure 9 Crystal phase diagram of the solder prepared for Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 of the present application; wherein a) Example 1, b) Example 2, c) Example 3, d) Example 4, e) Comparative Example 1. DETAILED DESCRIPTION

[0040] The following detailed description of various exemplary embodiments of the application should not be considered to be limiting of the application, but rather a description of certain specific aspects, features, and embodiments of the application.

[0041] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, for the purposes of the present application, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" includes reference to "one or more" and reference to "the" includes reference to "one or more" or "one or more and one or more". The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains" and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "a", "an" and "the" used in the context of the present application are to be construed to cover both the singular and the plural, unless otherwise indicated.

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0043] Various modifications and changes can be made to the specific embodiments of the application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0044] As used herein, the terms "comprise", "comprising", "include", "including", "contain", "containing", "have" and "having" are open-ended terms that are intended to mean "including, but not limited to".

[0045] The lead-free low-temperature solder described in the present application is mainly tin-indium solder, the added metal Bi has the solidification expansion property; the added metal Ga has excellent wettability and flowability; the present application does not add metal Pb, compared with the traditional solder, the multi-component tin-indium system lead-free low-temperature solder has the advantages of good thermal conductivity, good flowability, small expansion and shrinkage, environmental protection and safety, etc.

[0046] The embodiment of the present application provides a multi-component tin-indium series lead-free low-temperature solder, which comprises the following components in percentage by mass: Bi: 0.5-5%, Ga: 0.1-1.5%, and the rest is Sn25In matrix and inevitable impurities. Preferably, the multi-component tin-indium series lead-free low-temperature solder comprises the following components in percentage by mass: Bi: 0.99-2%, Ga: 0.1-1%, and the rest is Sn25In matrix and inevitable impurities.

[0047] In the following optional embodiments of the present application, the mass ratio of Sn and In in the Sn25In matrix is (72.75-74.18):(24.25-24.73). For example, in the following preferred embodiments of the present application, the mass ratio of Sn and In is 73.5:24.5, 72.75:24.25, 74.18:24.73 or 74.11:24.7.

[0048] The embodiment of the present application also provides a preparation method of the multi-component tin-indium series lead-free low-temperature solder, which comprises the following steps:

[0049] (1) preparing a Sn25In matrix: Sn raw materials are added into a lead-free graphite heating furnace and heated to be melted, then In raw materials are added and heated to be melted, and constant temperature stirring is performed to obtain the Sn25In matrix;

[0050] (2) proportionally weighing Bi, Ga and the Sn25In matrix and mixing to obtain a mixture, adding the mixture into a lead-free graphite heating furnace, adding an antioxidant, heating to be melted under a nitrogen atmosphere, constant temperature stirring, and casting in a mold to obtain the multi-component tin-indium series lead-free low-temperature solder.

[0051] In the following optional embodiments of the present application, the temperature of heating in step (1) is 300-350 DEG C. For example, in the following preferred embodiments of the present application, the temperature of heating is 350 DEG C.

[0052] In the following optional embodiments of the present application, the specific operation steps of constant temperature stirring in step (1) are stirring for 30 minutes at 300-350 DEG C. For example, in the following preferred embodiments of the present application, the specific operation steps of constant temperature stirring are stirring for 30 minutes at 350 DEG C.

[0053] In the following optional embodiments of the present application, the antioxidant in step (2) is rosin, which is uniformly coated on the surface to isolate air.

[0054] In the following optional embodiments of the present application, the temperature of heating in step (2) is 300-350 DEG C. For example, in the following preferred embodiments of the present application, the temperature of heating is 350 DEG C.

[0055] In the following optional embodiment of the present application, in step (2), the specific operation steps of the constant temperature stirring are: stirring for 30 minutes and then keeping for 30 minutes at 300-350℃, so as to mix the multiple elements uniformly. Exemplarily, in the following preferred embodiment of the present application, the specific operation steps of the constant temperature stirring are: stirring for 30 minutes and then keeping for 30 minutes at 350℃.

[0056] In the following optional embodiment of the present application, in step (2), the material of the mold is graphite.

[0057] The multi-component tin-indium series lead-free low-temperature solder can be applied in the field of microelectronic packaging low-temperature welding.

[0058] Exemplarily, in the following embodiment of the present application, the multi-component tin-indium series lead-free low-temperature solder comprises the following components in mass percentage: Bi: 0.99-2% (exemplarily, Bi is 0.99% or 2%), Ga: 0.1-1% (exemplarily, Ga is 0.1%, 0.19% or 1%), Sn: 72.75-74.18% (exemplarily, Sn is 72.75%, 73.5%, 74.11% or 74.18%), and In: 24.25-24.73% (exemplarily, In is 24.25%, 24.5%, 24.7% or 24.73%).

[0059] In the present application, “room temperature” refers to 20-30℃ unless otherwise specified.

[0060] In the present application, all raw materials are obtained by purchase in the market.

[0061] The technical solutions of the present application are further illustrated by the following examples.

[0062] Example 1

[0063] A multi-component tin-indium series lead-free low-temperature solder comprises the following components in mass percentage: Bi (bismuth): 1%, Ga (gallium): 1%, Sn (tin): 73.5%, and In (indium): 24.5%.

[0064] A preparation method of a multi-component tin-indium series lead-free low-temperature solder comprises the following steps:

[0065] (1) preparing Sn25In matrix: adding Sn into a lead-free graphite heating furnace and heating to melt at 350℃, then adding In and continuing to heat to melt at 350℃, stirring and keeping for 30 minutes after melting to obtain Sn25In matrix;

[0066] (2) proportionally weigh Bi, Ga and Sn25In matrix and mix to obtain a mixture, add the mixture into a lead-free graphite heating furnace, cover the mixture surface with an antioxidant rosin (the antioxidant is added in an amount capable of uniformly covering the mixture surface, the same below, to achieve the role of air isolation), heat to melt at 350°C under a nitrogen atmosphere, after melting, stir for 30 minutes and then keep warm for 30 minutes to make it uniformly mixed, cast in a graphite mold to obtain a multi-component tin indium series lead-free low-temperature solder.

[0067] Example 2

[0068] A multi-component tin indium series lead-free low-temperature solder, comprising the following components in mass percentage: Bi (bismuth): 2%, Ga (gallium): 1%, Sn (tin): 72.75%, In (indium): 24.25%.

[0069] A preparation method of a multi-component tin indium series lead-free low-temperature solder, comprising the following steps:

[0070] (1) Preparation of Sn25In matrix: add Sn into a lead-free graphite heating furnace and heat to melt at 350°C, then add In and continue to heat to melt at 350°C, after melting, stir and keep warm for 30 minutes to obtain a Sn25In matrix;

[0071] (2) proportionally weigh Bi, Ga and Sn25In matrix and mix to obtain a mixture, add the mixture into a lead-free graphite heating furnace, cover the mixture surface with an antioxidant rosin (the antioxidant is added in an amount capable of uniformly covering the mixture surface, the same below, to achieve the role of air isolation), heat to melt at 350°C under a nitrogen atmosphere, after melting, stir for 30 minutes and then keep warm for 30 minutes to make it uniformly mixed, cast in a graphite mold to obtain a multi-component tin indium series lead-free low-temperature solder.

[0072] Example 3

[0073] A multi-component tin indium series lead-free low-temperature solder, comprising the following components in mass percentage: Bi (bismuth): 0.99%, Ga (gallium): 0.1%, Sn (tin): 74.18%, In (indium): 24.73%.

[0074] A preparation method of a multi-component tin indium series lead-free low-temperature solder, comprising the following steps:

[0075] (1) Preparation of Sn25In matrix: add Sn into a lead-free graphite heating furnace and heat to melt at 350°C, then add In and continue to heat to melt at 350°C, after melting, stir and keep warm for 30 minutes to obtain a Sn25In matrix;

[0076] (2) Weigh Bi, Ga and Sn25In matrix in proportion and mix to obtain a mixture, add the mixture into a lead-free graphite heating furnace, cover the mixture surface with an antioxidant rosin, heat to melt at 350℃ under nitrogen atmosphere, after melting, stir for 30 minutes and then keep warm for 30 minutes to make the mixture uniform, cast in a graphite mold to obtain the multi-component tin indium series lead-free low-temperature solder.

[0077] Example 4

[0078] A multi-component tin indium series lead-free low-temperature solder, comprising the following components in mass percentage: Bi (bismuth): 0.99%, Ga (gallium): 0.2%, Sn (tin): 74.11%, In (indium): 24.7%.

[0079] A preparation method of a multi-component tin indium series lead-free low-temperature solder, comprising the following steps:

[0080] (1) Preparation of Sn25In matrix: add Sn into a lead-free graphite heating furnace and heat to melt at 350℃, then add In and continue to heat to melt at 350℃, after melting, stir and keep warm for 30 minutes to obtain the Sn25In matrix;

[0081] (2) Weigh Bi, Ga and Sn25In matrix in proportion and mix to obtain a mixture, add the mixture into a lead-free graphite heating furnace, cover the mixture surface with an antioxidant rosin, heat to melt at 350℃ under nitrogen atmosphere, after melting, stir for 30 minutes and then keep warm for 30 minutes to make the mixture uniform, cast in a graphite mold to obtain the multi-component tin indium series lead-free low-temperature solder.

[0082] Comparative Example 1

[0083] A Sn25In solder, comprising the following components in mass percentage: Sn (tin): 75%, In (indium): 25%.

[0084] A preparation method of a Sn25In solder, comprising the following steps: add Sn into a lead-free graphite heating furnace and heat to melt at 350℃, then add In and continue to heat to melt at 350℃, after melting, stir and keep warm for 30 minutes to obtain the Sn25In solder.

[0085] Comparative Example 2

[0086] The same as Example 1, except that the components are changed to Bi (bismuth): 2%, Ga (gallium): 0%, Sn (tin): 73.5%, In (indium): 24.5%.

[0087] The result is that the melting point is slightly higher than that of Examples 1-4, and the melting performance is general.

[0088] Comparative Example 3

[0089] Same as Example 1, except that the composition is changed to Bi (bismuth): 0.5%, Ga (gallium): 0.05%, Sn (tin): 74.5875%, In (indium): 24.8625%.

[0090] The results showed that the melting point was much higher than that of Examples 1-4, and the melting performance was very poor.

[0091] Performance testing:

[0092] 1. For welding materials, melting characteristics are an important aspect of their weldability. The melting points of the samples prepared in the examples and comparative examples were determined using a differential thermal analyzer at an acceleration rate of 5°C / min under nitrogen conditions. The results are as follows: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown.

[0093] Figure 1 The melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared in Example 1 of this invention is shown below. Figure 1 As can be seen, the melting temperature is 118.2℃.

[0094] Figure 2 The melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared in Example 2 of this invention is shown below. Figure 2 As can be seen, the melting temperature is 115.9℃.

[0095] Figure 3 The melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared in Example 3 of this invention is shown below. Figure 3 As can be seen, the melting temperature is 115.6℃.

[0096] Figure 4 The melting characteristic curve of the multi-component tin-indium-based lead-free low-temperature solder prepared in Example 4 of this invention is shown below. Figure 4 As can be seen from this, the melting temperature is 114.4℃.

[0097] Figure 5 The melting characteristic curve of the solder prepared in Comparative Example 1 of this invention is shown below. Figure 5 As can be seen, the melting temperature is 141.12℃.

[0098] Figure 6 The melting characteristic curve of the solder prepared in Comparative Example 2 of this invention is shown below. Figure 6 As can be seen, the melting temperature is 121.2℃;

[0099] Figure 7 The melting characteristic curve of the solder prepared in Comparative Example 3 of this invention is shown below. Figure 7 As can be seen, the melting temperature is 140.69℃.

[0100] By comparison Figures 1-7 It can be seen that the melting point of the multi-component tin-indium-based lead-free low-temperature solder prepared in Examples 1-4 is lower than that of Comparative Examples 1, 2, and 3, indicating that the multi-component tin-indium-based lead-free low-temperature solder prepared in Examples 1-4 of the present invention has a better low-temperature melting effect.

[0101] 2. The tensile strength of the solder is one of the important indicators for evaluating the quality of welding.

[0102] Figure 8 This is a comparison chart of the tensile strength of the solders prepared in Examples 1, 2, 3, 4, and Comparative Example 1 of the present invention. Figure 8 As shown, the tensile strength of Examples 1-4 is significantly improved compared with Comparative Example 1 because the added bismuth metal forms a solid solution or intermetallic compound with tin, which significantly improves the hardness and tensile strength of the solder. Although the added gallium metal will gradually reduce the tensile strength, it is still improved overall compared with the comparative example.

[0103] Figure 9 The crystal phase diagrams of the solders prepared in Examples 1, 2, 3, 4 and Comparative Example 1 of this invention are shown below. Figure 9 As can be seen, the microcracks in Comparative Example 1 are significantly wider than those in the other four examples, indicating that the solidification expansion characteristics of Bi effectively offset the welding stress, and the low melting point of Ga improves the melt fluidity, forming a dense and continuous gradient phase distribution. The addition of Bi element inhibits the formation of brittle phases (such as Sn3In4) in the Sn-In alloy and avoids the segregation of brittle networks at grain boundaries, while the wettability of Ga optimizes the bonding interface between the liquid metal and the matrix. No needle-like or blocky brittle phases were observed in the crystal phase diagram, only Sn-In solid solution and a small amount of uniformly dispersed second-phase particles were present.

[0104] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-component Sn-In based lead-free low temperature solder, characterized by, The raw material components include the following mass percentages: Bi: 0.5-5%, Ga: 0.1-1.5%, and the balance of Sn25In matrix and inevitable impurities.

2. The multi-component Sn-In based lead-free low temperature solder according to claim 1, wherein, The raw material components include the following mass percentages: Bi: 0.99-2%, Ga: 0.1-1%, and the balance of Sn25In matrix and inevitable impurities.

3. The multi-component Sn-In based lead-free low temperature solder according to claim 2, wherein The raw material components include the following mass percentages: Bi: 0.99-2%, Ga: 0.1-1%, and the balance of Sn25In matrix and inevitable impurities.

4. A method for producing a multi-component Sn-In-based lead-free low-temperature solder according to any one of claims 1 to 3, characterized by, The method comprises the following steps: Preparation of Sn25In matrix; The Bi, Ga and Sn25In matrix are weighed in proportion and mixed to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, an antioxidant is added, and the second heating is carried out under a nitrogen atmosphere until the material is melted, and then the second constant temperature stirring is carried out, and the material is cast in a mold to obtain the multi-component tin indium lead-free low-temperature solder.

5. The preparation method according to claim 4, characterized in that, The preparation method of the Sn25In matrix comprises the following steps: Sn raw material is added into a lead-free graphite heating furnace for first heating until the material is melted, then In raw material is added, and heating is continued until melting, and first constant temperature stirring is carried out to obtain the Sn25In matrix.

6. The production method according to claim 5, wherein The temperature of the first heating is 300-350°C; and / or, The specific operation steps of the first constant temperature stirring are: stirring at 300-350°C for 30 minutes.

7. The preparation method according to claim 4, characterized in that, The antioxidant is rosin.

8. The preparation method according to claim 4, characterized in that, The temperature of the second heating is 300-350°C; and / or, The specific operation steps of the second constant temperature stirring are: stirring at 300-350°C for 30 minutes and then holding for 30 minutes.

9. The preparation method according to claim 4, characterized in that, The material of the mold is graphite.

10. Application of the multi-component tin indium lead-free low-temperature solder according to any one of claims 1-3 in the field of microelectronic packaging low-temperature welding.

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