Single-core solder wire and preparation method thereof

Abstract

The invention discloses a single-core solder wire and a preparation method thereof, and relates to the field of welding materials, the single-core solder wire comprises an alloy solder layer and a soldering flux layer which are sequentially arranged from outside to inside, and the alloy solder layer is prepared from 10-15 wt% of Bi, 0.5-1.5 wt% of Cu, 1-3 wt% of Ag, 0.05-0.35 wt% of Ti, 0.05-0.2 wt% of Zn, 0.01-0.2 wt% of Ni, 0.55-0.85 wt% of Sn-Be-Sb ternary alloy and the balance Sn. The scaling powder layer is prepared from modified rosin, organic acid, organic amine, a surfactant, an antioxidant, a corrosion inhibitor and an organic solvent according to a specific proportion. The prepared single-core solder wire is good in ductility, and the processing performance of the single-core solder wire in a low-temperature environment and the stability performance of a welding spot in the low-temperature environment can be improved.

Description

Technical Field

[0001] The present application relates to the field of welding materials, and in particular to a single-core solder wire and a preparation method thereof. Background Art

[0002] Single-core solder wire is a commonly used welding material, which is mainly composed of two parts: tin alloy and flux. Among them, traditional solder wire mostly adopts a simple alloy system, such as the common tin-lead alloy. However, the lead element in the tin-lead alloy has potential hazards to the environment and human health. With the increasing environmental protection requirements, the solder wire is urged to develop towards lead-free, resulting in the emergence of alloy solders such as tin-bismuth alloy and tin-bismuth-copper alloy. However, the existing tin-bismuth alloy and tin-bismuth-copper alloy are prone to low-temperature brittleness problems, which is not conducive to the processing and forming of single-core solder wire, and will also reduce the stability of solder joints in low-temperature environments. Summary of the invention

[0003] In order to improve the problem that the existing single-core solder wire is prone to low-temperature brittleness in a low-temperature environment, resulting in reduced stability of the solder joint in a low-temperature environment, the present application provides a single-core solder wire and a preparation method thereof.

[0004] In the first aspect, the present application provides a single-core solder wire adopting the following technical solution: A single-core solder wire comprises an alloy solder layer and a flux layer which are sequentially arranged from the outside to the inside, wherein the alloy solder layer is made of 10-15wt% Bi, 0.5-1.5wt% Cu, 1-3wt% Ag, 0.05-0.35wt% Ti, 0.05-0.2wt% Zn, 0.01-0.2wt% Ni, 0.55-0.85wt% Sn-Be-Sb ternary alloy and the balance Sn, and the raw materials for preparing the flux layer include modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent; Among them, in the Sn-Be-Sb ternary alloy, the weight percentage of Be is 2.3-2.8%, the weight percentage of Sb is 1.5-2.0%, and Sn is the balance; the weight ratio of the modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent is (55-60): (4.5-5.5): (3.2-3.6): (0.1-0.15): (1.5-2.5): (0.2-0.3): (15-20).

[0005] The single-core solder wire in the present application includes an alloy solder layer and a flux layer arranged in sequence from the outside to the inside. Among them, the alloy solder layer is made of a specific ratio of Bi (bismuth), Cu (copper), Ag (silver), Ti (titanium), Zn (zinc), Ni (nickel), Sn (tin)-Be (beryllium)-Sb (antimony) ternary alloy and Sn (tin). The joint action of each element in a specific ratio is conducive to improving the oxidation resistance and low-temperature brittleness of the alloy solder layer, improving the processing performance of the single-core solder wire in a low-temperature environment and the stability of the solder joint in a low-temperature environment. In addition, the flux layer is made of a specific ratio of modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent. The flux layer can help remove impurities such as oxide film and oil stains on the surface of the metal to be welded, and at the same time provide good wettability, so that the alloy solder layer can be evenly spread on the surface of the metal to be welded after melting, ensuring that the solder joint is firm and reliable.

[0006] In some preferred embodiments, the alloy solder layer is made of 12-12.5wt% Bi, 0.5-0.8wt% Cu, 1.5-2wt% Ag, 0.1-0.2wt% Ti, 0.1-0.15wt% Zn, 0.05-0.1wt% Ni, 0.6-0.65wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0007] In the present application, it is preferred that the ratio of the raw materials of the alloy solder layer is within the above range, which is beneficial to further improve the low-temperature brittleness of the alloy solder layer and can improve the stability of the solder joint in a low-temperature environment.

[0008] In some preferred embodiments, the method for preparing the Sn-Be-Sb ternary alloy comprises the following steps: S1. After Sn is melted at 240-250°C in an inert gas environment, the temperature is raised to 350-360°C, Sb and Be are added, stirred and melted uniformly, and then the temperature is lowered to 200-220°C and kept warm for 0.5-1h to obtain a molten material; S2. pouring the molten material into a mold and cooling it to obtain a Sn-Be-Sb ternary alloy.

[0009] In the present application, after Sn, Sb and Be are melted evenly, the temperature is lowered to 200-220°C and kept warm for 0.5-1h, which is beneficial to improving the Sn-Be-Sb ternary alloy prepared by the above preparation method, improving the low-temperature brittleness of the alloy solder layer, and improving the stability of the solder joint in a low-temperature environment.

[0010] In some preferred embodiments, the modified rosin includes rosin pentaerythritol ester and rosin modified phenolic resin, and the weight ratio of the rosin pentaerythritol ester to the rosin modified phenolic resin is (3-4):1.

[0011] In this application, when soldering the pins of electronic components and the copper foil of the printed circuit board, the use of rosin pentaerythritol ester alone may not have ideal wettability on some tiny solder joints or slightly oxidized surfaces, while the use of rosin modified phenolic resin alone may cause some potential corrosion problems due to excessive activity. After the modified rosin adopts a mixture of rosin pentaerythritol ester and rosin modified phenolic resin in a specific ratio, the flux can be quickly spread around the solder joint, so that the alloy solder can fill the tiny gap between the pin and the copper foil, forming a full, smooth and firm solder joint.

[0012] In some preferred embodiments, the organic acid is malic acid and adipic acid, and the weight ratio of malic acid to adipic acid is (1-1.5):1; the organic amine is at least one of monoethanolamine, diethanolamine and triethanolamine.

[0013] Malic acid has a stronger acidity than adipic acid. The organic acid of the present application adopts a composition of malic acid and adipic acid in a specific weight ratio, which can effectively remove the oxide film and prevent the corrosion of the welded metal.

[0014] In some preferred embodiments, the surfactant is Tween 20 or Tween 60.

[0015] In some preferred embodiments, the antioxidant is an aromatic aldehyde, and the corrosion inhibitor is at least one of benzothiazole.

[0016] In some preferred embodiments, the organic solvent is anhydrous ethanol.

[0017] Compared with ether solvents (such as propylene glycol butyl ether and propylene glycol propyl ether), the use of anhydrous ethanol as an organic solvent is more conducive to the uniform mixing of the components, which is beneficial to improving the filling performance of the flux and preventing the occurrence of single-core solder wire core breakage problems.

[0018] In some preferred embodiments, the weight percentage of the flux layer is 1.1-2.2%.

[0019] In the present application, the weight proportion of the flux layer is controlled at 1.1-2.2%, which can help remove impurities such as oxide film and oil stains on the surface of the metal to be welded, provide good wettability, reduce flux residue, and improve the firmness of the solder joint.

[0020] In a second aspect, the present application provides a method for preparing a single-core solder wire using the following technical solution: After the modified rosin is heated and melted, a mixed solution of organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent is added, and after being mixed evenly, a soldering flux is obtained, which is kept at a constant temperature of 145-155°C for standby use; A ternary alloy of Sn, Bi, Cu, Ag, Ti, Zn, Ni and Sn-Be-Sb is put into a vacuum melting furnace, and after being uniformly melted at 615-625°C under nitrogen protection, the temperature is lowered to 420-450°C, kept constant for 1-2 hours, and then cast and extruded to obtain an alloy solder; the alloy solder and flux are extruded into a single-core solder wire with a diameter of 8-10 mm by a hydraulic press, and then drawn into a single-core solder wire with a diameter range of 0.25-0.3 mm by a wire drawing machine.

[0021] The present application adopts the above method to prepare the single-core solder wire, which can reduce the defective rate of the single-core solder wire and reduce the occurrence of the problem of single-core solder wire core breakage.

[0022] In summary, this application at least includes the following beneficial technical effects: (1) The single-core solder wire in the present application includes an alloy solder layer and a flux layer arranged in sequence from the outside to the inside. Among them, the alloy solder layer is made of a specific ratio of Bi (bismuth), Cu (copper), Ag (silver), Ti (titanium), Zn (zinc), Ni (nickel), Sn (tin)-Be (beryllium)-Sb (antimony) ternary alloy and Sn (tin). The combined effect of the elements in the specific ratio is conducive to improving the oxidation resistance and low-temperature brittleness of the alloy solder layer, improving the processing performance of the single-core solder wire in a low-temperature environment and the stability of the solder joint in a low-temperature environment. In addition, the flux layer is made of a specific ratio of modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent. The flux layer can help remove impurities such as oxide film and oil stains on the surface of the metal to be welded, and at the same time provide good wettability, so that the alloy solder layer can be evenly spread on the surface of the metal to be welded after melting, ensuring that the solder joint is firm and reliable.

[0023] (2) In the application, by optimizing the ratio of the raw materials of the alloy solder layer, it is beneficial to further improve the low-temperature brittleness of the alloy solder layer and improve the stability of the solder joint in a low-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the single-core solder wire of the present application.

[0025] Description of reference numerals: 1. Alloy solder layer; 2. Flux layer. DETAILED DESCRIPTION

[0026] The present application is further described below in conjunction with specific experiments. Example

[0027] [Example 1] A single-core solder wire comprises an alloy solder layer 1 and a flux layer 2 which are sequentially arranged from the outside to the inside, wherein the flux layer 2 accounts for 2.2% of the weight of the single-core solder wire. The alloy solder layer 1 is made of 10wt% Bi, 1.5wt% Cu, 1wt% Ag, 0.35wt% Ti, 0.2wt% Zn, 0.01wt% Ni, 0.85wt% Sn-Be-Sb ternary alloy and the balance Sn, wherein the weight percentage of Be is 2.3%, the weight percentage of Sb is 1.5%, and Sn is the balance, and the preparation method of the Sn-Be-Sb ternary alloy comprises the following steps: S1. After Sn is melted at 250°C in an inert gas environment, the temperature is raised to 350°C, Sb and Be are added, stirred and melted evenly, and then the temperature is lowered to 220°C and kept for 0.5h to obtain a molten material; S2. Pour the molten material into a mold and cool it to obtain a Sn-Be-Sb ternary alloy.

[0028] The raw materials for preparing the flux layer 2 include 55kg modified rosin, 4.5kg organic acid, 3.2kg diethanolamine, 0.1kg Tween 20, 1.5kg benzaldehyde, 0.2kg benzotriazole and 15kg anhydrous ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin (Senya SY-Q1), the weight ratio of 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin is 3:1, and the organic acid includes malic acid and adipic acid, and the weight ratio of malic acid and adipic acid is 1:1.

[0029] In this embodiment, the preparation method of the single-core solder wire includes the following steps: After the modified rosin is heated and melted, a mixed solution of organic acid, diethanolamine, Tween 20, benzaldehyde, benzotriazole and anhydrous ethanol is added, and after being mixed evenly, a soldering flux is obtained, which is kept at a constant temperature of 145°C for use; Put Sn, Bi, Cu, Ag, Ti, Zn, Ni and Sn-Be-Sb ternary alloy into a vacuum melting furnace, and melt them uniformly at 615°C under nitrogen protection, then cool them to 450°C, keep the temperature constant for 1 hour, and then cast and extrude them to obtain alloy solder; The alloy solder and flux are squeezed into a single-core solder wire with a diameter of 10 mm by a hydraulic press, and then drawn into a single-core solder wire with a diameter of 0.3 mm by a wire drawing machine.

[0030] [Example 2] A single-core solder wire comprises an alloy solder layer 1 and a flux layer 2 which are sequentially arranged from the outside to the inside, wherein the flux layer 2 accounts for 1.1% of the weight of the single-core solder wire. The alloy solder layer 1 is made of 15wt% Bi, 0.5wt% Cu, 3wt% Ag, 0.05wt% Ti, 0.05wt% Zn, 0.2wt% Ni, 0.55wt% Sn-Be-Sb ternary alloy and the balance Sn, wherein the weight percentage of Be is 2.8%, the weight percentage of Sb is 2.0%, and Sn is the balance, and the preparation method of the Sn-Be-Sb ternary alloy comprises the following steps: S1. After Sn is melted at 240°C in an inert gas environment, the temperature is raised to 360°C, Sb and Be are added, stirred and melted uniformly, and then the temperature is lowered to 200°C and kept for 1 hour to obtain a molten material; S2. Pour the molten material into a mold and cool it to obtain a Sn-Be-Sb ternary alloy.

[0031] The raw materials for preparing the flux layer 2 include 60kg modified rosin, 5.5kg organic acid, 3.6kg triethanolamine, 0.15kg Tween 60, 2.5kg benzaldehyde, 0.3kg benzothiazole and 20kg anhydrous ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin (Senya SY-Q1), the weight ratio of 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin is 4:1, and the organic acid includes malic acid and adipic acid, and the weight ratio of malic acid and adipic acid is 1.5:1.

[0032] In this embodiment, the preparation method of the single-core solder wire includes the following steps: After the modified rosin is heated and melted, a mixed solution of organic acid, triethanolamine, Tween 60, benzaldehyde, benzothiazole and anhydrous ethanol is added, and after being mixed evenly, a soldering flux is obtained, which is kept at a constant temperature of 155°C for use; Put Sn, Bi, Cu, Ag, Ti, Zn, Ni and Sn-Be-Sb ternary alloy into a vacuum melting furnace, and melt evenly at 625°C under nitrogen protection, then cool to 420°C, keep constant temperature for 2h, and then cast and extrude to obtain alloy solder; The alloy solder and flux are squeezed into a single-core solder wire with a diameter of 8 mm by a hydraulic press, and then drawn into a single-core solder wire with a diameter of 0.25 mm by a wire drawing machine.

[0033] [Example 3] A single-core solder wire, which is different from [Example 1] in that the proportions of the components in the alloy solder layer 1 are different.

[0034] The alloy solder layer 1 is made of 12 wt % Bi, 0.65 wt % Cu, 1.8 wt % Ag, 0.15 wt % Ti, 0.12 wt % Zn, 0.08 wt % Ni, 0.65 wt % Sn-Be-Sb ternary alloy and the balance Sn.

[0035] [Example 4] A single-core solder wire, which is different from [Example 1] in that the proportions of the components in the alloy solder layer 1 are different.

[0036] The alloy solder layer 1 is made of 15wt% Bi, 1.0wt% Cu, 2.5wt% Ag, 0.25wt% Ti, 0.2wt% Zn, 0.2wt% Ni, 0.85wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0037] Comparative Example [Comparative Example 1] A single-core solder wire, which is different from [Example 1] in that the proportions of the components in the alloy solder layer 1 are different.

[0038] In this comparative example, the alloy solder layer is made of 10wt% Bi, 2.5wt% Cu, 4.0wt% Ag, 0.5wt% Ti, 1.0wt% Zn, 0.4wt% Ni, 0.15wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0039] [Comparative Example 2] A single core solder wire, which differs from [Example 1] in that the ratio of each element in the Sn-Be-Sb ternary alloy used in the alloy solder layer 1 is different.

[0040] In the Sn-Be-Sb ternary alloy used in this comparative example, the weight percentage of Be is 1.8%, the weight percentage of Sb is 5.6%, and Sn is the balance.

[0041] [Comparative Example 3] A single-core solder wire, which differs from [Example 1] in that the proportions of the components in the flux layer 2 are different.

[0042] In this comparative example, the raw materials for preparing the flux layer 2 include 65kg modified rosin, 8.5kg organic acid, 6.8kg diethanolamine, 0.3kg Tween 20, 0.5kg benzaldehyde, 0.1kg benzotriazole and 15kg anhydrous ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin (Senya SY-Q1), the weight ratio of 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin is 1:1, and the organic acid includes malic acid and adipic acid, and the weight ratio of malic acid and adipic acid is 1:3.

[0043] Performance testing 1. Ductility: The single-core solder wires prepared in the examples and comparative examples were placed in an environment of 5°C and -10°C for 48 hours, and then subjected to ductility tests according to ASTM E290 "Standard Test Method for Bend Test of Ductility of Materials". The bending angles were 90° and 45°, respectively. If there was no cracking, the test was passed, otherwise the test failed. The better the ductility, the better the performance of the single-core solder wire in resisting low-temperature brittleness.

[0044] 2. Spreading coefficient: Referring to GB / T 11364-89 "Test method for spreadability and filling property of solder", the spreading coefficient of the single-core solder wire prepared in each embodiment and comparative example was tested. The spreading substrate was a 0.2 mm thick pure copper sheet, the test temperature was 400°C, and the test time was 10 s. The larger the spreading coefficient, the better the wettability of the single-core solder wire, which is beneficial to improving the welding strength of the solder joint.

[0045] 3. Tensile strength of solder joints: The single-core solder wires prepared in the embodiments and comparative examples were used to prepare the test samples. Other conditions of the test samples were kept consistent. The tensile strength of the solder joints of the test samples was tested with reference to GB / T 2651-2023 "Destructive test of welds of metallic materials - transverse tensile test". The test temperature was 25°C.

[0046] Table 1 Table 2 Sample Spreading coefficient / % Tensile strength of solder joint / MPa Example 1 82.5 46.23 Example 2 82.1 46.14 Example 3 82.7 46.29 Example 4 82.4 46.19 Comparative Example 1 78.8 43.26 Comparative Example 2 78.4 43.15 Comparative Example 3 77.3 42.56 Combining Example 1 with Comparative Examples 1-3 and the test data in Table 1-2, it can be seen that when the ratio of each raw material in the alloy solder layer and the ratio of the Sn-Be-Sb ternary alloy are not within the scope of this application, the low-temperature ductility of the single-core solder wire will be affected, which is not conducive to the processing of the single-core solder wire in a low-temperature environment, and the composition of the flux layer affects the spreadability of the alloy solder and the welding strength of the solder joint.

[0047] Combining Example 1 with Examples 3-4 and the test data in Table 1-2, it can be seen that the preferred ratio of the components of the alloy solder layer can further improve the low-temperature brittleness of the alloy solder layer, which is beneficial to the winding of the single-core solder wire in a low-temperature environment with a lower temperature, and can also improve the stability of the solder joint in a low-temperature environment with a lower temperature.

[0048] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A single core solder wire, characterized in that: The invention comprises an alloy solder layer (1) and a flux layer (2) which are arranged in sequence from the outside to the inside, wherein the alloy solder layer (1) is made of 10-15wt% Bi, 0.5-1.5wt% Cu, 1-3wt% Ag, 0.05-0.35wt% Ti, 0.05-0.2wt% Zn, 0.01-0.2wt% Ni, 0.55-0.85wt% Sn-Be-Sb ternary alloy and the balance Sn, and the raw materials for preparing the flux layer (2) include modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent; Among them, in the Sn-Be-Sb ternary alloy, the weight percentage of Be is 2.3-2.8%, the weight percentage of Sb is 1.5-2.0%, and Sn is the balance; the weight ratio of the modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent is (55-60): (4.5-5.5): (3.2-3.6): (0.1-0.15): (1.5-2.5): (0.2-0.3): (15-20).

2. The single-core solder wire according to claim 1, characterized in that: The alloy solder layer (1) is made of 12-12.5wt% Bi, 0.5-0.8wt% Cu, 1.5-2wt% Ag, 0.1-0.2wt% Ti, 0.1-0.15wt% Zn, 0.05-0.1wt% Ni, 0.6-0.65wt% Sn-Be-Sb ternary alloy and the balance Sn.

3. A single-core solder wire according to claim 1 or 2, characterized in that: The preparation method of the Sn-Be-Sb ternary alloy comprises the following steps: S1. After Sn is melted at 240-250°C in an inert gas environment, the temperature is raised to 350-360°C, Sb and Be are added, stirred and melted uniformly, and then the temperature is lowered to 200-220°C and kept warm for 0.5-1h to obtain a molten material; S2. pouring the molten material into a mold and cooling it to obtain a Sn-Be-Sb ternary alloy.

4. The single-core solder wire according to claim 3, characterized in that: The modified rosin includes rosin pentaerythritol ester and rosin modified phenolic resin, and the weight ratio of the rosin pentaerythritol ester to the rosin modified phenolic resin is (3-4):

1.

5. The single-core solder wire according to claim 3, characterized in that: The organic acid is malic acid and adipic acid, and the weight ratio of malic acid to adipic acid is (1-1.5):1; the organic amine is at least one of monoethanolamine, diethanolamine and triethanolamine.

6. The single-core solder wire according to claim 3, characterized in that: The surfactant is Tween 20 or Tween 60.

7. The single-core solder wire according to claim 3, characterized in that: The antioxidant is aromatic aldehyde, and the corrosion inhibitor is at least one of benzotriazole and benzothiazole.

8. The single-core solder wire according to claim 3, characterized in that: The organic solvent is anhydrous ethanol.

9. The single-core solder wire according to claim 3, characterized in that: The weight proportion of the flux layer is 1.1-2.2%.

10. A method for preparing a single-core solder wire according to any one of claims 1 to 9, characterized in that: The following steps are involved: After the modified rosin is heated and melted, a mixed solution of organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent is added, and after being mixed evenly, a soldering flux is obtained, which is kept at a constant temperature of 145-155°C for standby use; Put Sn, Bi, Cu, Ag, Ti, Zn, Ni and Sn-Be-Sb ternary alloy into a vacuum melting furnace, and melt them uniformly at 615-625°C under nitrogen protection, then cool them to 420-450°C, keep the temperature constant for 1-2 hours, and then cast and extrude them to obtain alloy solder; The alloy solder and the solder flux are squeezed into a single-core solder wire with a diameter of 8-10 mm by a hydraulic press, and then drawn into a single-core solder wire with a diameter ranging from 0.25 to 0.3 mm by a wire drawing machine.

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