Nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth series solder and preparation method thereof

Abstract

The invention discloses a nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth series solder and a preparation method thereof, and belongs to the technical field of microelectronic packaging. The solder comprises the following components in percentage by mass: 0.5 to 3.0 percent of In, 0.5 to 2.5 percent of Ag, 0.1 to 1.0 percent of nano CeO2, and the balance of Sn58Bi matrix and a small amount of inevitable impurities. The preparation method comprises the following steps: preparing the Sn58Bi matrix, mixing the In, the Ag, the nano CeO2 and the Sn58Bi matrix in proportion, adding the antioxidant, heating and stirring, and casting and molding. The solder has good wettability, comprehensive mechanical properties and corrosion resistance, is suitable for microelectronic packaging low-temperature welding, and is low in cost and high in market competitiveness.

Description

TECHNICAL FIELD

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

[0002] In the field of electronic manufacturing, soldering technology is always the key link to connect electronic components and build reliable circuit systems. In recent years, with the enhancement of global environmental awareness and the stipulation of relevant regulations, traditional lead-containing solder is gradually restricted due to its potential harm to the environment and human health. This change has promoted the rapid development of lead-free soldering technology, which has become the mainstream process in the electronic manufacturing industry.

[0003] Among the many lead-free solder systems, tin bismuth (Sn-Bi) solder is widely studied due to its relatively low melting point. The eutectic composition Sn58Bi alloy has a melting point of only 138-140℃, which is significantly lower than that of traditional Sn-Pb solder (183℃) and widely used SAC series alloy (Sn-Ag-Cu, melting point 217-221℃). This characteristic greatly reduces the soldering temperature during reflow soldering, which is generally controlled at 240-260℃, greatly alleviating the thermal shock on temperature-sensitive components and substrate materials, effectively reducing component damage and substrate deformation caused by high temperature, and widening the range of materials that can be used in electronic manufacturing, providing strong support for the lightweight and high-performance design of new electronic equipment. However, it has the problems of greater brittleness and easy crack propagation when subjected to mechanical stress or thermal cycle stress, leading to solder joint failure and poor fatigue resistance.

[0004] In summary, there is an urgent need to develop a lead-free, environmentally friendly, cost-effective, and superior comprehensive mechanical property tin bismuth alloy solder suitable for microelectronic packaging. SUMMARY

[0005] To solve the above technical problems, the present application provides a nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder and a preparation method thereof. The method has a simple process flow and is environmentally friendly. The prepared low-temperature solder has good wettability and comprehensive mechanical properties, and is suitable for low-temperature soldering in the field of microelectronic packaging technology.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] One of the purposes of the present application is to provide a nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder, which comprises the following components by mass percentage: In: 0.5-3.0%, Ag: 0.5-2.5%, nano CeO2: 0.1-1.0%, and the balance is Sn58Bi matrix and an unavoidable small amount of impurities.

[0008] The multi-component lead-free low-temperature solder provided by the application is mainly a tin-bismuth alloy, the Bi element can reduce the melting point of the solder alloy, and no intermetallic compound is generated between Bi and Sn, the yield strength, tensile strength, wettability and weldability are equivalent, the addition of In element can increase the ductility of the alloy, the microhardness of the alloy is enhanced, and the alloy is lead-free and non-toxic and environment-friendly, the Ag element has high conductivity and can inhibit oxidation and electrochemical corrosion, and the addition of the Ag element to the solder alloy can improve the tensile strength of the alloy and significantly improve the mechanical strength and fatigue resistance of the solder, the nano CeO2 does not react with the solder matrix and cannot generate new intermetallic compounds, and the nano CeO2 has high hardness, wear resistance and corrosion resistance, and can control the growth of the IMC layer and improve the mechanical properties of the solder joint.

[0009] Further, in the Sn58Bi matrix, the mass ratio of Sn and Bi is (40-42) : (56-58).

[0010] The second object of the application is to provide a preparation method of the nano ceria doped multi-component lead-free low-temperature tin-bismuth solder, which comprises the following steps:

[0011] Preparation of the Sn58Bi matrix;

[0012] The In, Ag, nano CeO2 and Sn58Bi matrix are weighed according to the proportion and mixed to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, an antioxidant is added, heated to melt, constant temperature stirring, and cast in a mold to obtain the nano ceria doped multi-component lead-free low-temperature tin-bismuth solder.

[0013] Further, the specific preparation steps of the Sn58Bi matrix include: Sn is added into a lead-free graphite heating furnace, heated to melt, then Bi is added, and heated to melt, and constant temperature stirring is performed to obtain the Sn58Bi matrix.

[0014] Further, the temperature of the heating is 250-350 DEG C; and / or,

[0015] The specific operation steps of the constant temperature stirring are: stirring at 250-350 DEG C for 30 minutes.

[0016] Further, the addition amount of the antioxidant is 1-3% of the mass of the mixture, and the antioxidant is rosin, which is uniformly coated on the surface to isolate air.

[0017] Further, the temperature of the heating is 300-500 DEG C; and / or

[0018] The specific operation steps of the constant temperature stirring are: stirring at 300-500 DEG C for 10-30 minutes.

[0019] Further, the material of the mold is graphite.

[0020] The third object of the present application is to provide an application of the nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder in the field of microelectronic packaging low-temperature welding.

[0021] Compared with the prior art, the present application has the following advantages and technical effects:

[0022] 1. Large product profit space: the addition amount of expensive metals In and Ag in the product prepared by the present application is extremely small, and the price of CeO2 is relatively low, so the comprehensive cost is not expensive. However, due to the excellent strengthening effect of the three on the comprehensive performance of tin bismuth solder, the present application has leading performance compared with traditional solder, and is beneficial to occupy the high-end market in the appropriate price range.

[0023] 2. Suitable for scenes with strict performance requirements: the synergistic effect of the added In, Ag and nano CeO2 can significantly enhance the conductivity, mechanical properties, fatigue resistance and corrosion resistance of the solder joint, and compared with traditional solder, the present application is more suitable for high-precision and other fields with strict performance requirements.

[0024] 3. Strong application adaptability: the component ratio of In, Ag and nano CeO2 can be adjusted to meet the special needs of certain specific performance in the use process. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the application, and are incorporated herein for purposes of illustrating the illustrative embodiments of the present application and the explanations provided herein and are not intended as a limitation. In the drawings:

[0026] Figure 1 is the melting characteristic curve of the mixed material in the embodiment 1 of the present application;

[0027] Figure 2 is the melting characteristic curve of the mixed material in the embodiment 2 of the present application;

[0028] Figure 3 is the melting characteristic curve of the mixed material in the embodiment 3 of the present application;

[0029] Figure 4 is the melting characteristic curve of the mixed material in the embodiment 4 of the present application;

[0030] Figure 5 is the tensile strength comparison diagram of the embodiment 1, the embodiment 2 and the comparative example 1 of the present application;

[0031] Figure 6 is the elongation at break comparison diagram of the embodiment 1, the embodiment 2 and the comparative example 1 of the present application;

[0032] Figure 7 Tensile strength comparison chart for inventive example 3, inventive example 4, and comparative example 2;

[0033] Figure 8 Tensile strength comparison chart for inventive example 3, inventive example 4, and comparative example 3;

[0034] Figure 9 Crystal phase chart for inventive examples 1-4, comparative examples 1-2, where (a) comparative example 1; (b) inventive example 2; (c) inventive example 1; (d) comparative example 2; (e) inventive example 3; (f) inventive example 4. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present application will now be described in detail, without intent to limit the application, which is only limited by the claims. Understanding that these embodiments are illustrative of the application, it will thus be readily understood that various changes can be made by one skilled in the art without departing from the scope of the application, which is set forth by the claims.

[0036] 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, the use of "including," "comprising," "having," "containing," and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless otherwise indicated, the use of the approximately or about symbol (e.g., ~) in the description or claims should not be construed to mean a deviation of 10% or less, but rather should be construed to mean a deviation of about 20% or less, preferably about 10% or less, more preferably about 5% or less, and most preferably about 1% or less.

[0037] 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 any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference to the extent allowed by law. In the case of conflict between the descriptions mentioned herein and the incorporated references, the present specification shall control.

[0038] Various modifications and changes can be made to the specific embodiments 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 in any way.

[0039] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or variants thereof are open-ended, and include one or more steps, integers, compositions or elements listed thereafter, but not to the exclusion of any additions thereof.

[0040] The lead-free low-temperature solder provided by the application is mainly tin bismuth solder, and the added metal In has low melting point and high wettability; the added metal Ag can improve the shear strength and fracture energy of the solder joint; the added nano cerium dioxide can refine the microstructure of the composite solder, improve the mechanical properties of the solder and improve the corrosion resistance; and no metal Pb is added in the application. Compared with the traditional solder, the In, Ag and nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder has the advantages of high strength, good wettability, corrosion resistance, environmental protection and safety.

[0041] The embodiment of the application provides a nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder, which comprises the following components in percentage by mass: In: 0.5-3.0%, Ag: 0.5-2.5%, nano CeO2: 0.1-1.0%, and the balance is Sn58Bi matrix and an unavoidable small amount of impurities.

[0042] In some preferred embodiments, the nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder comprises the following components in percentage by mass: In: 1-2% (for example, 1%, 1.5% or 2%), Ag: 0.5-1.5% (for example, 0.5%, 1%, 1.25% or 1.5%), nano CeO2: 0.2-0.5% (for example, 0.2%, 0.3% or 0.5%), and the balance is Sn58Bi matrix and an unavoidable small amount of impurities.

[0043] In some optional embodiments, in the Sn58Bi matrix, the mass ratio of Sn and Bi is (40-42):(56-58). For example, in the following embodiments of the application, the mass ratio of Sn and Bi is 40.32:55.68, 40.782:56.318, 41.034:56.666 or 41.286:57.014.

[0044] The embodiment of the application also provides a preparation method of the nano cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder, comprising the following steps:

[0045] (1) preparing a Sn58Bi matrix: adding Sn into a lead-free graphite heating furnace, heating to melt at 250-350 DEG C, then adding Bi, continuing to heat to melt at 250-350 DEG C, stirring and keeping at the temperature for 30 minutes after melting to obtain the Sn58Bi matrix;

[0046] (2) proportionally weigh In, Ag, nano-CeO2 and Sn58Bi matrix and mix to obtain a mixture, add the mixture into a lead-free graphite heating furnace, cover the mixture with an antioxidant, heat to melting at 300-500℃, after melting, stir and keep at the temperature for 10-30 minutes to ensure uniform dispersion of nano-CeO2 in the solder and uniform mixing of various elements, then cast in a mold to obtain a nano-CeO2 doped multi-component lead-free low-temperature tin bismuth solder.

[0047] In some optional embodiments, in step (1), the heating temperature is 250-350℃. For example, in the following embodiments of the present application, the heating temperature is 350℃.

[0048] In some optional embodiments, in step (1), the constant temperature stirring has the following specific operation steps: stirring at 250-350℃ for 30 minutes. For example, in the following embodiments of the present application, the constant temperature stirring refers to stirring at 350℃ for 30 minutes.

[0049] In some optional embodiments, in step (2), the antioxidant is added in an amount of 1-3% of the mass of the mixture.

[0050] In some preferred embodiments, in step (2), the antioxidant is rosin.

[0051] In some optional embodiments, in step (2), the heating temperature is 300-500℃. For example, in the following embodiments of the present application, the heating temperature is 350℃ or 500℃.

[0052] In some optional embodiments, in step (2), the constant temperature stirring has the following specific operation steps: stirring at 300-500℃ for 10-30 minutes. For example, in the following embodiments of the present application, the constant temperature stirring refers to stirring at 350℃ or 500℃ for 10 minutes.

[0053] In some optional embodiments, in step (2), the mold is made of graphite.

[0054] As an example, in the following preferred embodiments of the present application, the nano-CeO2 doped multi-component lead-free low-temperature tin bismuth solder includes the following components by mass percentage: In: 1-2% (as an example, such as 1%, 1.5%, or 2%), Ag: 0.5-1.5% (as an example, such as 0.5%, 1%, 1.25%, or 1.5%), nano-CeO2: 0.2-0.5% (as an example, such as 0.2%, 0.3%, or 0.5%), Sn: 40-42% (as an example, such as 40.32%, 40.761%, 41.034%, or 41.286%), Bi: 56-58% (as an example, such as 55.68%, 56.289%, 56.666%, or 57.014%), and inevitable impurities.

[0055] The nano-CeO2 doped multi-component lead-free low-temperature tin bismuth solder provided by the present application can be applied in the field of microelectronic packaging low-temperature soldering.

[0056] In the present application, “room temperature” refers to 20-30°C unless otherwise specified.

[0057] In the present application, all raw materials are commercially available.

[0058] In the present application, “58” in “Sn58Bi matrix” refers to the content of Bi in the matrix.

[0059] The technical solutions of the present application are further illustrated by the following examples.

[0060] Example 1

[0061] A nano-CeO2 doped multi-component lead-free low-temperature tin bismuth solder includes the following components by mass percentage: In: 1%, Ag: 0.5%, nano-CeO2: 0.2%, Sn: 41.286%, and Bi: 57.014%.

[0062] A method for preparing a nano-CeO2 doped multi-component lead-free low-temperature tin bismuth solder includes the following steps:

[0063] (1) Preparation of Sn58Bi matrix: Sn is added to a lead-free graphite heating furnace and heated to melt at 350°C, then Bi is added and heated to melt at 350°C, and after melting, stirring and holding at the temperature for 30 minutes to obtain a Sn58Bi matrix;

[0064] (2) taking In, Ag, nano CeO2 and Sn58Bi matrix by proportion and mixing to obtain a mixture, adding the mixture into a lead-free graphite heating furnace, covering the surface of the mixture with an antioxidant (the antioxidant is rosin, and the adding amount is 1-3% of the mass of the mixture, and the specific amount is enough to uniformly cover the surface and achieve the role of air isolation, and the same is applicable below), heating to melting at 350°C, stirring and keeping warm for 10 minutes after melting at the temperature, and then casting in a mold to obtain a nano ceria doped multi-component lead-free low-temperature tin bismuth solder.

[0065] Example 2

[0066] A nano ceria doped multi-component lead-free low-temperature tin bismuth solder includes the following mass percentage of components: In: 1%, Ag: 1%, nano CeO2: 0.3%, Sn: 41.034%, Bi: 56.666%.

[0067] A preparation method of a nano ceria doped multi-component lead-free low-temperature tin bismuth solder includes the following steps:

[0068] (1) preparing a Sn58Bi matrix: adding Sn into a lead-free graphite heating furnace, heating to melting at 350°C, then adding Bi, continuing to heat to melting at 350°C, and stirring and keeping warm for 30 minutes after melting at the temperature to obtain the Sn58Bi matrix;

[0069] (2) taking In, Ag, nano CeO2 and Sn58Bi matrix by proportion and mixing to obtain a mixture, adding the mixture into a lead-free graphite heating furnace, covering the surface of the mixture with an antioxidant, heating to melting at 350°C, stirring and keeping warm for 10 minutes after melting at the temperature, and then casting in a mold to obtain a nano ceria doped multi-component lead-free low-temperature tin bismuth solder.

[0070] Example 3

[0071] A nano ceria doped multi-component lead-free low-temperature tin bismuth solder includes the following mass percentage of components: In: 1.5%, Ag: 1.25%, nano CeO2: 0.2%, Sn: 40.761%, Bi: 56.289%.

[0072] A preparation method of a nano ceria doped multi-component lead-free low-temperature tin bismuth solder includes the following steps:

[0073] (1) preparing a Sn58Bi matrix: adding Sn into a lead-free graphite heating furnace, heating to melting at 350°C, then adding Bi, continuing to heat to melting at 350°C, and stirring and keeping warm for 30 minutes after melting at the temperature to obtain the Sn58Bi matrix;

[0074] (2) In, Ag, nano-CeO2 and Sn58Bi base are weighed according to the proportion and mixed to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, an antioxidant is covered on the surface of the mixture, heated to melting at 500℃, after melting, stirred and kept at the temperature for 10 minutes, then cast in a mold to obtain a nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder.

[0075] Example 4

[0076] A nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder comprises the following components by mass percentage: In: 2%, Ag: 1.5%, nano-CeO2: 0.5%, Sn: 40.32%, Bi: 55.68%.

[0077] A preparation method of a nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder comprises the following steps:

[0078] (1) Preparation of Sn58Bi base: Sn is added into a lead-free graphite heating furnace, heated to melting at 350℃, then Bi is added, continue to heat to melting at 350℃, after melting, stirred and kept at the temperature for 30 minutes to obtain a Sn58Bi base;

[0079] (2) In, Ag, nano-CeO2 and Sn58Bi base are weighed according to the proportion and mixed to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, an antioxidant is covered on the surface of the mixture, heated to melting at 500℃, after melting, stirred and kept at the temperature for 10 minutes, then cast in a mold to obtain a nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder.

[0080] Comparative Example 1

[0081] A tin bismuth solder comprises the following components by mass percentage: Sn: 42%, Bi: 58%.

[0082] A preparation method of a tin bismuth solder comprises the following steps: Sn is added into a lead-free graphite heating furnace, heated to melting at 350℃, then Bi is added, continue to heat to melting at 350℃, after melting, stirred and kept at the temperature for 30 minutes to obtain a Sn58Bi base.

[0083] Comparative Example 2

[0084] An In doped lead-free low-temperature tin bismuth solder comprises the following components by mass percentage: In: 2%, Sn: 41.16%, Bi: 56.84%.

[0085] A preparation method of an In-doped lead-free low-temperature tin bismuth solder, comprising the following steps:

[0086] (1) preparing a Sn58Bi matrix: Sn is added into a lead-free graphite heating furnace, heated to melt at 350 DEG C, then Bi is added, and heated to melt at 350 DEG C, after melting, stirring and keeping at the temperature for 30 minutes to obtain the Sn58Bi matrix;

[0087] (2) taking In and Sn58Bi matrix by proportion and mixing to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, the surface of the mixture is covered with an antioxidant, heated to melt at 350 DEG C, after melting, stirring and keeping at the temperature for 10 minutes, then cast in a mold to obtain the In-doped lead-free low-temperature tin bismuth solder.

[0088] Comparative Example 3

[0089] An In, Ag-doped multi-component lead-free low-temperature tin bismuth solder, comprising the following components by mass percentage: In: 1.94%, Ag: 3%, Sn: 39.93%, Bi: 55.13%.

[0090] A preparation method of an In, Ag-doped multi-component lead-free low-temperature tin bismuth solder, comprising the following steps:

[0091] (1) preparing a Sn58Bi matrix: Sn is added into a lead-free graphite heating furnace, heated to melt at 350 DEG C, then Bi is added, and heated to melt at 350 DEG C, after melting, stirring and keeping at the temperature for 30 minutes to obtain the Sn58Bi matrix;

[0092] (2) taking In, Ag and Sn58Bi matrix by proportion and mixing to obtain a mixture, the mixture is added into a lead-free graphite heating furnace, the surface of the mixture is uniformly covered with an antioxidant, heated to melt at 500 DEG C, after melting, stirring and keeping at the temperature for 10 minutes, then cast in a mold to obtain the In, Ag-doped multi-component lead-free low-temperature tin bismuth solder.

[0093] Figure 1 The melting characteristic curve of the mixture in Example 1 of the present application has little difference in melting point from that of pure tin bismuth alloy. Figure 5 And Figure 6 The elongation at break and tensile strength of the In, Ag-doped multi-component lead-free low-temperature tin bismuth solder are stronger than those of the pure tin bismuth alloy in Comparative Example 1. Figure 9 From the above, it can be obviously seen that the ductility of the In, Ag-doped multi-component lead-free low-temperature tin bismuth solder is obviously better than that of the pure tin bismuth alloy in Comparative Example 1.

[0094] Figure 2The melting characteristic curve of the mixed material in the embodiment 2 of the present application has a melting point slightly higher than that of the pure tin bismuth alloy, but in combination with Figure 5 and Figure 6 , the elongation at break and tensile strength are stronger than those of the pure tin bismuth alloy in the comparative example 1, especially the elongation at break is greatly improved. From Figure 9 it can also be seen that the addition of more Ag refines the metallographic structure, because Ag3Sn intermetallic compound is generated, which is beneficial to the enhancement of the tensile strength of the alloy.

[0095] Figure 3 The melting characteristic curve of the mixed material in the embodiment 3 of the present application has a melting point significantly lower than that of the pure tin bismuth alloy in the comparative example 1, but in combination with Figure 7 and Figure 8 , the appropriate amount of Ag and nano-CeO2 addition can improve the tensile strength. From Figure 9 it can be clearly seen that after the addition of nano-CeO2, the ductility is obviously better than that of the comparative examples 2 and 3 without the addition of nano-CeO2.

[0096] Figure 4 The melting characteristic curve of the mixed material in the embodiment 4 of the present application has a melting point significantly lower than that of the pure tin bismuth alloy in the comparative example 1. Compared with the embodiment 3, more In, Ag and nano-CeO2 are added, but from Figure 7 and Figure 8 it can be seen that the performance is not greatly improved, and the tensile strength is still higher than that of the comparative examples 2 and 3.

[0097] The tensile strength and elongation at break are one of the important indicators for evaluating the welding quality. The tensile strength and elongation at break of the solders prepared in the embodiments 1-4 are obviously improved compared with the comparative examples, so the solder prepared by the present application has stronger mechanical properties and can meet the use requirements of the electronic packaging industry.

[0098] Figure 9 The crystal phase diagrams of the embodiments 1-4 and the comparative examples 1-2 are shown in the figures, wherein (a) is the comparative example 1, (b) is the embodiment 2, (c) is the embodiment 1, (d) is the comparative example 2, (e) is the embodiment 3 and (f) is the embodiment 4.

[0099] Table 1 shows the spreading rate results of the comparative examples 1-2 and the embodiments 1-4.

[0100] Table 1 shows the spreading rate test results of the alloys

[0101]

[0102] As can be seen from Table 1, the higher the spreading rate, the stronger the flowability of the solder on the substrate, the larger the coverage area, and the improvement of the spreading rate often reflects the improvement of the wetting performance. As can be seen from the table, the addition of nano cerium dioxide can well improve the spreading rate, and with the increase of the nano cerium dioxide addition amount within a reasonable range, the spreading rate shows an upward trend, and compared with the comparative example 1 and the comparative example 2 without adding, the spreading rate is well improved.

[0103] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A nano ceria-doped multi-component lead-free low temperature tin bismuth based solder, characterized by, The components include the following mass percentages: In: 0.5-3.0%, Ag: 0.5-2.5%, nano-CeO2: 0.1-1.0%, and the rest is Sn58Bi matrix and inevitable small amount of impurities.

2. The nanoceraium-doped, multi-component, lead-free, low-temperature, tin-bismuth based solder of claim 1, wherein, The components include the following mass percentages: In: 1-2%, Ag: 0.5-1.5%, nano-CeO2: 0.2-0.5%, and the rest is Sn58Bi matrix and inevitable small amount of impurities.

3. The nanocerium dioxide-doped, multi-component, lead-free, low-temperature, tin-bismuth-based solder according to claim 1 or 2, characterized in that In the Sn58Bi matrix, the mass ratio of Sn and Bi is (40-42):(56-58).

4. A method for producing a nano ceria-doped multi-component lead-free low-temperature tin bismuth-based solder according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: Preparation of Sn58Bi matrix; In, Ag, nano-CeO2 and Sn58Bi 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, heated to melt, constant temperature stirring, cast in a mold to obtain a nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder.

5. The method for preparing the nano-cerium dioxide-doped multi-component lead-free low-temperature tin-bismuth solder according to claim 4, characterized in that, The specific preparation steps of the Sn58Bi matrix include: Sn is added into a lead-free graphite heating furnace, heated to melt, then Bi is added, and heated to melt, constant temperature stirring to obtain the Sn58Bi matrix.

6. The method of claim 5, wherein the nanocerium-doped multi-component lead-free low-temperature Sn-Bi based solder is prepared by the steps of: The temperature of the heating is 250-350°C; and / or, The specific operation steps of the constant temperature stirring are: stirring at 250-350°C for 30 minutes.

7. The method of claim 4, wherein the nano ceria-doped multi-component lead-free low-temperature Sn-Bi based solder is prepared by the steps of: (a) preparing a Sn-Bi based solder alloy; (b) adding ceria to the Sn-Bi based solder alloy; (c) mixing the Sn-Bi based solder alloy and ceria; and (d) sintering the Sn-Bi based solder alloy and ceria. The antioxidant is added in an amount of 0.1-0.3% of the mass of the mixture; the antioxidant is rosin.

8. The method of claim 4, wherein the nano ceria-doped multi-component lead-free low-temperature Sn-Bi based solder is prepared by the steps of: The temperature of the heating is 300-500°C; and / or The specific operation steps of the constant temperature stirring are: stirring at 300-500°C for 10-30 minutes.

9. The method for preparing the nano-cerium dioxide-doped multi-component lead-free low-temperature tin-bismuth solder according to claim 4, characterized in that, The material of the mold is graphite.

10. Application of the nano-cerium dioxide doped multi-component lead-free low-temperature tin bismuth solder according to any one of claims 1-3 in the field of microelectronic packaging low-temperature soldering.

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