An alloy solder and a method of making the same

Abstract

The application discloses alloy solder and a preparation method thereof, and relates to the technical field of welding. The alloy solder prepared by the application is a tin-based alloy solder, which comprises tin, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium. The melting point of bismuth is relatively low, which can reduce the eutectic temperature of the alloy, so that the alloy solder can be used for low-temperature welding. However, the wettability of the solder is reduced. Therefore, a small amount of cerium is added at the same time when the bismuth is added. Under the synergistic effect of the cerium, the bismuth and the erbium, the wettability is improved, and the alloy solder is refined. A small amount of nitrogen-doped cerium oxide is further added, which can inhibit the growth of alloy eutectic compounds in the alloy solder in the non-homogeneous nucleation center, so that the cerium, the bismuth and the erbium in the solder can play the maximum role. In addition, the solder is rapidly cooled during the cooling and solidification of the solder, so that the size of each dendrite in the alloy is reduced. When the high-melting-point nitrogen-doped cerium oxide is uniformly dispersed in the solder, the crystal phase structure of the multi-component alloy solder is uniform, and the crystal grains are more refined.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to an alloy solder and a preparation method thereof. BACKGROUND

[0002] At present, there are many kinds of solders used in electronic products, but most of them still use tin-lead alloy solder. Since tin-lead solder contains lead which pollutes the environment, the European Union has issued two directives to prohibit the use of lead-containing tin solder in electronic products since July 1, 2006. Most of the existing lead-free solders are composed of tin-silver, tin-copper, tin-silver-copper, tin-zinc-indium-bismuth, tin-antimony-silver-indium, tin-zinc-nickel, and a few are composed of tin-copper-nickel. The excellent heat resistance and cycle performance of the solder make the lithium ion battery further develop in the new energy field.

[0003] However, the existing lead-free tin solder has the defects of small wettability, coarse crystallization and high melting point, which limits the use of tin alloy solder. Therefore, the present application studies an alloy solder with strong wettability, uniform crystal phase organization and more refined grains to broaden the development of tin alloy solder. SUMMARY

[0004] The purpose of the present application is to provide an alloy solder and a preparation method thereof to solve the problems raised in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: an alloy solder, which is a tin-based alloy solder, further comprising silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium.

[0006] Preferably, the alloy solder is composed of the following raw materials in weight percentage: silver 0.2-0.4%, copper 1-3%, nickel 0.1-0.3%, cerium 0.04-0.06%, nitrogen-doped cerium oxide 0.25-0.45%, bismuth 1.4-3.8%, and erbium 0.2-0.4%, and the rest is tin.

[0007] Preferably, the purity of the tin is 99.5-99.9%.

[0008] Preferably, the nitrogen-doped cerium oxide is prepared by doping nitrogen through heat treatment when preparing cerium oxide.

[0009] Preferably, the alloy solder is prepared by mixing and smelting tin, silver, copper, nickel, cerium, bismuth and erbium and then cooling and solidifying; and the cooling and solidification is performed by rapid cooling.

[0010] Preferably, the preparation method of the alloy solder comprises the following specific steps:

[0011] The SM-600 lead-free tin melting furnace is used, the tin is melted, and then the temperature is increased to 1500-1800 DEG C, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium are added, and then the melting is continued, the complete melting is stirred uniformly, the temperature is kept for 20-40 min, and then the alloy solder is prepared by pouring into a mold and rapid cooling.

[0012] Preferably, the temperature of the molten tin is 270-290 DEG C.

[0013] Preferably, the preparation method of the nitrogen-doped cerium oxide is as follows: sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed according to the mass ratio of 1-1.8:100:8-9, and then stirred and dissolved, the temperature is increased to 90-110 DEG C, and then the hydrothermal treatment is carried out for 24-28 h, and then the deionized water and ethanol are used for washing 3-5 times, and then the nitrogen-doped cerium oxide is prepared by drying and calcining at 800-900 DEG C under nitrogen atmosphere for 2-4 h.

[0014] Preferably, the water cooling is used in the rapid cooling, and the solidification rate is 80-120 DEG C / s.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The alloy solder prepared by the present application is a tin-based alloy solder; and the alloy solder comprises tin, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium.

[0017] In the present application, cerium, nitrogen-doped cerium oxide, bismuth and erbium are added on the basis of tin, silver, copper and nickel; the melting point of bismuth is low, and the addition of bismuth makes the main crystal phase of the alloy be the beta-tin phase with a body-centered cubic structure and the bismuth phase with a rhombic layered structure, so that the eutectic temperature of the alloy is reduced, and the alloy solder can be used for low-temperature welding; however, the introduction of a large amount of bismuth increases the segregation degree of bismuth, and the phase transformation is coarse, so that the solubility of bismuth in tin is small, the interface layer thickness is increased, and the wettability of the solder is reduced; therefore, a small amount of cerium is added at the same time, the cerium is a surface active element, and the cerium and erbium are segregated on the surface of the alloy, so that the surface activity of the alloy is enhanced, and the surface tension of the solder is reduced; under the synergistic effect of cerium, bismuth and erbium, the wetting capacity is improved; and the electronegativity of cerium is greatly different from that of tin, and the cerium has strong affinity for tin, so that the formed metal compound is a non-homogeneous nucleation center of crystallization, and the alloy solder is refined.

[0018] A small amount of nitrogen-doped cerium oxide is further added to the heterogeneous nucleation center. The nitrogen-doped cerium oxide does not react with the elements in the solder, has high hardness, and can be used as a second phase particle to inhibit the growth of alloy intermetallic compounds in the heterogeneous nucleation center, so that the solder cerium, bismuth and erbium can play the maximum role. In addition, the alloy is rapidly cooled during the cooling and solidification of the solder, which reduces the size of each dendrite in the alloy, so that the high-melting-point nitrogen-doped cerium oxide is uniformly dispersed in the solder, and at the same time, the crystal phase structure of the multi-component alloy solder is uniform and the crystal grains are more refined. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] In order to more clearly illustrate the method provided by the present application, the following examples are used to illustrate the method in detail. The test methods of various indexes of the alloy solders prepared in the examples and comparative examples are as follows:

[0021] Melting point temperature: the melting point temperature range of the alloy solders prepared in the examples and comparative examples is tested by using a MH100 type metal melting point tester.

[0022] Wettability: the maximum wetting force of the soldering of the alloy solders prepared in the examples and comparative examples is tested by using a SWB-2 type solderability tester according to the J-STD-002 wetting balance method. Example 1

[0023] The alloy solder is composed of the following raw materials in weight percentage: silver 0.2%, copper 1%, nickel 0.1%, cerium 0.04%, nitrogen-doped cerium oxide 0.25, bismuth 1.4%, and erbium 0.2%, and the rest is tin.

[0024] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed in a mass ratio of 1:100:8, stirred and dissolved, heated to 90°C, hydrothermally treated for 24h, then washed with deionized water and ethanol for 3 times, dried, and then calcined at 800°C in a nitrogen atmosphere for 2h to obtain nitrogen-doped cerium oxide; tin is melted at 270°C by using a SM-600 lead-free tin melting furnace, heated to 1500°C after melting, and then silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium are added for further melting. After complete melting, uniform stirring is performed, heat preservation is performed for 20min, casting is performed into a mold, water cooling is performed, the solidification rate is 80°C / s, and the alloy solder is prepared. Example 2

[0025] The alloy solder is composed of the following raw materials in percentage by weight: silver 0.3%, copper 2%, nickel 0.2%, cerium 0.05%, nitrogen-doped cerium oxide 0.35%, bismuth 2.6%, and erbium 0.3%, and the rest is tin;

[0026] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water, and cerium nitrate hexahydrate are mixed in a mass ratio of 1.4:100:8.5, stirred and dissolved, heated to 100℃, hydrothermally treated for 26h, then washed with deionized water and ethanol for 4 times, dried, and then calcined at 850℃ in a nitrogen atmosphere for 3h to obtain nitrogen-doped cerium oxide; tin is melted at 280℃ using an SM-600 lead-free tin melting furnace, then heated to 1700℃ after melting, and then silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth, and erbium are added for continuous melting, and then stirred uniformly after complete melting, and then held for 30min, and then poured into a mold for water cooling, and then the solidification rate is 100℃ / s to obtain the alloy solder. Example 3

[0027] The alloy solder is composed of the following raw materials in percentage by weight: silver 0.4%, copper 3%, nickel 0.3%, cerium 0.06%, nitrogen-doped cerium oxide 0.45%, bismuth 3.8%, and erbium 0.4%, and the rest is tin;

[0028] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water, and cerium nitrate hexahydrate are mixed in a mass ratio of 1.8:100:9, stirred and dissolved, heated to 110℃, hydrothermally treated for 28h, then washed with deionized water and ethanol for 5 times, dried, and then calcined at 900℃ in a nitrogen atmosphere for 4h to obtain nitrogen-doped cerium oxide; tin is melted at 290℃ using an SM-600 lead-free tin melting furnace, then heated to 1800℃ after melting, and then silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth, and erbium are added for continuous melting, and then stirred uniformly after complete melting, and then held for 40min, and then poured into a mold for water cooling, and then the solidification rate is 120℃ / s to obtain the alloy solder.

[0029] Comparative Example 1

[0030] The alloy solder is composed of the following raw materials in percentage by weight: silver 0.3%, copper 2%, nickel 0.2%, cerium 0.05%, nitrogen-doped cerium oxide 0.35%, bismuth 2.6%, and the rest is tin;

[0031] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed in a mass ratio of 1.8:100:9, stirred and dissolved, then heated to 110°C, hydrothermally treated for 28h, then washed with deionized water and ethanol for 5 times, dried, then calcined at 900°C in a nitrogen atmosphere for 4h to obtain nitrogen-doped cerium oxide; tin is melted at 280°C using an SM-600 lead-free tin melting furnace, then heated to 1700°C after melting, silver, copper, nickel, cerium, nitrogen-doped cerium oxide and bismuth are added for continuous melting, then stirred uniformly after complete melting, kept for 30min, then cast into a mold, water-cooled rapidly, the solidification rate is 100°C / s, and the alloy solder is obtained.

[0032] Comparative Example 2

[0033] The alloy solder is composed of the following raw materials in weight percentage: silver 0.3%, copper 2%, nickel 0.2%, cerium 0.05%, nitrogen-doped cerium oxide 0.35% and erbium 0.3%, and the rest is tin;

[0034] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed in a mass ratio of 1.8:100:9, stirred and dissolved, then heated to 110°C, hydrothermally treated for 28h, then washed with deionized water and ethanol for 5 times, dried, then calcined at 900°C in a nitrogen atmosphere for 4h to obtain nitrogen-doped cerium oxide; tin is melted at 280°C using an SM-600 lead-free tin melting furnace, then heated to 1700°C after melting, silver, copper, nickel, cerium, nitrogen-doped cerium oxide and bismuth are added for continuous melting, then stirred uniformly after complete melting, kept for 30min, then cast into a mold, water-cooled rapidly, the solidification rate is 100°C / s, and the alloy solder is obtained.

[0035] Comparative Example 3

[0036] The alloy solder is composed of the following raw materials in weight percentage: silver 0.3%, copper 2%, nickel 0.2%, nitrogen-doped cerium oxide 0.35%, bismuth 2.6% and erbium 0.3%, and the rest is tin;

[0037] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed in a mass ratio of 1.8:100:9, stirred and dissolved, then heated to 110°C, hydrothermally treated for 28h, then washed with deionized water and ethanol for 5 times, dried, then calcined at 900°C in a nitrogen atmosphere for 4h to obtain nitrogen-doped cerium oxide; tin is melted at 280°C using an SM-600 lead-free tin melting furnace, then heated to 1700°C after melting, silver, copper, nickel, nitrogen-doped cerium oxide, bismuth and erbium are added for continuous melting, then stirred uniformly after complete melting, kept for 30min, then cast into a mold, water-cooled rapidly, the solidification rate is 100°C / s, and the alloy solder is obtained.

[0038] Comparative Example 4

[0039] The alloy solder is composed of the following raw materials in percentage by weight: silver 0.3%, copper 2%, nickel 0.2%, cerium 0.05%, nitrogen-doped cerium oxide 0.35%, bismuth 2.6%, and erbium 0.3%, and the rest is tin;

[0040] The preparation method of the alloy solder is as follows: sodium hydroxide, deionized water, and cerium nitrate hexahydrate are mixed in a mass ratio of 1.8:100:9, stirred and dissolved, heated to 110°C, and hydrothermally treated for 28h. Then, the product is washed with deionized water and ethanol for 5 times, dried, and calcined at 900°C in a nitrogen atmosphere for 4h to obtain nitrogen-doped cerium oxide. Tin is melted in an SM-600 lead-free tin melting furnace at 280°C, and then heated to 1700°C. After melting, silver, copper, nickel, cerium, bismuth, and erbium are added for continuous melting. After complete melting, uniform stirring is performed, and the product is kept at temperature for 30min. Then, the product is cast into a mold, and air-cooled to obtain the alloy solder.

[0041] Comparative Example 5

[0042] The alloy solder is composed of the following raw materials in percentage by weight: silver 0.3%, copper 2%, nickel 0.2%, cerium 0.05%, bismuth 2.6%, and erbium 0.3%, and the rest is tin;

[0043] The preparation method of the alloy solder is as follows: tin is melted in an SM-600 lead-free tin melting furnace at 280°C, and then heated to 1700°C. After melting, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth, and erbium are added for continuous melting. After complete melting, uniform stirring is performed, and the product is kept at temperature for 30min. Then, the product is cast into a mold, and water-cooled to obtain the alloy solder at a solidification rate of 100°C / s.

[0044] Effect Example

[0045] Table 1 below shows the performance analysis results of the alloy solders prepared by using Examples 1 to 3 and Comparative Examples 1 to 5 of the present application:

[0046]

[0047] Note: Smaller grains refer to grains with a size of not more than 40μm, and larger grains refer to grains with a size of more than 50μm.

[0048] As can be obviously seen from the experimental data of the examples and comparative examples in Table 1, the alloy solders prepared by using Examples 1, 2, and 3 have lower melting points, better wettability, and smaller grains.

[0049] From the experimental data comparison of example 1, example 2, example 3 and comparative example 1, comparative example 2, comparative example 3, it can be found that the melting point of bismuth is lower, which can reduce the eutectic temperature of the alloy, so that the alloy solder can be welded at low temperature, but the introduction of more bismuth increases the segregation degree of bismuth, reduces the wettability of the solder, therefore, a small amount of cerium is added at the same time of introducing bismuth, cerium is a surface active element, which cooperates with erbium to segregate on the surface of the alloy, so as to enhance the surface activity of the alloy, thereby reducing the surface tension of the solder, under the synergistic effect of cerium, bismuth and erbium, the wetting ability is improved; and the electronegativity of cerium is quite different from that of tin, which has strong affinity for tin, and the formed metal compound is called inhomogeneous nucleation center of crystallization, so that the alloy solder is refined.

[0050] From the experimental data comparison of example 1, example 2, example 3 and comparative example 4, comparative example 5, it can be found that on the basis of tin, silver, copper and nickel, cerium, bismuth and erbium are added, and a small amount of nitrogen-doped cerium oxide is further added, which is introduced into the inhomogeneous nucleation center, the nitrogen-doped cerium oxide will not react with the elements in the solder, and has high hardness, which can be used as a second phase particle to inhibit the growth of alloy eutectic compounds in the alloy solder in the inhomogeneous nucleation center, so that cerium, bismuth and erbium in the solder can play the maximum role; in addition, the alloy is rapidly cooled during the cooling and solidification of the solder, which reduces the size of each dendrite in the alloy, so that the high melting point nitrogen-doped cerium oxide is uniformly dispersed in the solder, and at the same time, the crystal phase organization of the multi-component alloy solder is uniform, and the grain is more refined.

[0051] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any mark in the claims should not be regarded as limiting the involved claims.

Claims

1. An alloy solder, characterized in that, The alloy solder is a tin-based alloy solder, and also includes silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth, and erbium; the alloy solder is composed of the following raw materials in weight percentages: silver 0.2-0.4%, copper 1-3%, nickel 0.1-0.3%, cerium 0.04-0.06%, nitrogen-doped cerium oxide 0.25-0.45%, bismuth 1.4-3.8%, and erbium 0.2-0.4%, with the remainder being tin.

2. The alloy solder according to claim 1, characterized in that, The purity of the tin is 99.5% to 99.9%.

3. The alloy solder according to claim 1, characterized in that, The nitrogen-doped cerium oxide is prepared by thermal treatment to dope nitrogen during the preparation of cerium oxide.

4. The alloy solder according to claim 1, characterized in that, The alloy solder is prepared by mixing and melting tin, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium, and then cooling and solidifying it; the cooling and solidification process involves rapid cooling.

5. A method for preparing an alloy solder according to any one of claims 1-4, characterized in that, The preparation method of the alloy solder includes the following specific steps: using an SM-600 lead-free tin melting furnace, after melting tin, the temperature is raised to 1500-1800℃, silver, copper, nickel, cerium, nitrogen-doped cerium oxide, bismuth and erbium are added and the melting continues. After complete melting, the mixture is stirred evenly, kept at the temperature for 20-40 minutes, poured into a mold, and rapidly cooled to obtain the alloy solder.

6. The method for preparing an alloy solder according to claim 5, characterized in that, In the above steps, the temperature during molten tin is 270–290°C.

7. The method for preparing an alloy solder according to claim 5, characterized in that, In the above steps, the preparation method of nitrogen-doped cerium oxide is as follows: Sodium hydroxide, deionized water and cerium nitrate hexahydrate are mixed in a mass ratio of 1-1.8:100:8-9, stirred and dissolved, heated to 90-110℃, hydrothermally heated for 24-28 hours, washed 3-5 times with deionized water and ethanol, dried and calcined at 800-900℃ in a nitrogen atmosphere for 2-4 hours to obtain nitrogen-doped cerium oxide.

8. The method for preparing an alloy solder according to claim 5, characterized in that, In the above steps: water cooling is used for rapid cooling, and the solidification rate is 80-120℃ / s.

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