A single-core solder wire and its preparation method

Abstract

The present invention discloses a single-core solder wire and a preparation method thereof, relating to the field of welding materials. The single-core solder wire includes an alloy solder layer and a flux layer arranged in sequence from outside to inside. 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. The preparation raw materials of the flux layer include modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent in specific proportions. The single-core solder wire prepared in this application has good ductility, and can improve 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.

Description

Technical Field

[0001] This application relates to the field of welding materials, and particularly 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 mainly consists of two parts: tin alloy and flux. Among them, traditional solder wires mostly adopt simple alloy systems, such as the common tin-lead alloy. However, the lead element in the tin-lead alloy poses potential hazards to the environment and human health. With the increasing environmental protection requirements, it has promoted the development of solder wires towards lead-free, thus emerging 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 are not conducive to the processing and forming of single-core solder wires 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 low-temperature environments, resulting in a decrease in the stability of solder joints in low-temperature environments, this application provides a single-core solder wire and a preparation method thereof.

[0004] In a first aspect, a single-core solder wire provided by this application adopts the following technical solution:

[0005] A single-core solder wire includes an alloy solder layer and a flux layer arranged in sequence from outside to inside. 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. The preparation raw materials of the flux layer include modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent;

[0006] 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).

[0007] The single-core solder wire in this application includes a solder alloy layer and a flux layer arranged in sequence from outside to inside. Among them, the solder alloy layer is made of Bi (bismuth), Cu (copper), Ag (silver), Ti (titanium), Zn (zinc), Ni (nickel), Sn (tin)-Be (beryllium)-Sb (antimony) ternary alloy and Sn with specific ratios. The combined action of elements with specific ratios is conducive to improving the oxidation resistance and low-temperature brittleness of the solder alloy layer, and enhancing the processing performance of the single-core solder wire in low-temperature environments and the stability of solder joints in low-temperature environments. In addition, the flux layer is made of modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent with specific ratios. This flux layer can help remove impurities such as oxide films and oil stains on the surface of the metal to be soldered, and at the same time provide good wettability, enabling the solder alloy layer to spread evenly on the surface of the metal to be soldered after melting, ensuring the firmness and reliability of the solder joints.

[0008] In some preferred embodiments, the solder alloy layer is made of 12 - 12.5 wt% Bi, 0.5 - 0.8 wt% Cu, 1.5 - 2 wt% Ag, 0.1 - 0.2 wt% Ti, 0.1 - 0.15 wt% Zn, 0.05 - 0.1 wt% Ni, 0.6 - 0.65 wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0009] In this application, it is preferred that the ratios of the raw materials of the solder alloy layer are within the above ranges, which is conducive to further improving the low-temperature brittleness of the solder alloy layer and can enhance the stability of the solder joints in low-temperature environments.

[0010] In some preferred embodiments, the preparation method of the Sn-Be-Sb ternary alloy includes the following steps:

[0011] S1. After melting Sn in an inert gas environment at 240 - 250 °C, raise the temperature to 350 - 360 °C, add Sb and Be, stir and melt evenly, and then cool down to 200 - 220 °C and keep warm for 0.5 - 1 h to obtain a molten material;

[0012] S2. Pour the molten material into a mold, cool it, and obtain the Sn-Be-Sb ternary alloy.

[0013] In this application, after melting Sn, Sb and Be evenly and then cooling down to 200 - 220 °C and keeping warm for 0.5 - 1 h, it is conducive to improving the Sn-Be-Sb ternary alloy prepared by the above preparation method, which is conducive to improving the low-temperature brittleness of the solder alloy layer and enhancing the stability of the solder joints in low-temperature environments.

[0014] In some preferred embodiments, the modified rosin includes pentaerythritol ester of rosin and rosin modified phenolic resin, and the weight ratio of the pentaerythritol ester of rosin to the rosin modified phenolic resin is (3 - 4):1.

[0015] In this application, when soldering the pins of electronic components to the copper foil of a printed circuit board, using rosin pentaerythritol ester alone may result in insufficient wettability on some tiny solder joints or slightly oxidized surfaces, while using rosin-modified phenolic resin alone may cause some potential corrosion problems due to excessive activity. After using a mixture of rosin pentaerythritol ester and rosin-modified phenolic resin in a specific ratio as the modified rosin, the flux can spread rapidly around the solder joints, enabling the alloy solder to fill into the tiny gaps between the pins and the copper foil, forming plump, smooth, and firm solder joints.

[0016] 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.

[0017] Malic acid has stronger acidity than adipic acid. Using a composition of malic acid and adipic acid in a specific weight ratio as the organic acid in this application can effectively remove the oxide film while preventing corrosion problems of the metal to be soldered.

[0018] In some preferred embodiments, the surfactant is Tween 20 or Tween 60.

[0019] In some preferred embodiments, the antioxidant is aromatic aldehyde, and the corrosion inhibitor is at least one of benzothiazole.

[0020] In some preferred embodiments, the organic solvent is absolute ethanol.

[0021] Compared with using ether solvents (such as propylene glycol butyl ether and propylene glycol propyl ether), using absolute ethanol as the organic solvent is more conducive to the uniform mixing of each component, is beneficial to improving the filling performance of the flux, and prevents the occurrence of the problem of broken cores in single-core solder wires.

[0022] In some preferred embodiments, the weight percentage of the flux layer is 1.1 - 2.2%.

[0023] In this application, controlling the weight percentage of the flux layer at 1.1 - 2.2% can help remove impurities such as oxide films and oil stains on the surface of the metal to be soldered, provide good wettability, and can reduce the residue of the flux, improving the firmness of the solder joints.

[0024] In a second aspect, a preparation method of a single-core solder wire provided by this application adopts the following technical solution:

[0025] After heating and melting the modified rosin, add a mixed solution of organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent. After mixing evenly, a soldering flux is obtained and kept at a constant temperature of 145-155°C for standby;

[0026] Put Sn, Bi, Cu, Ag, Ti, Zn, Ni, Sn-Be-Sb ternary alloy into a vacuum melting furnace. Under nitrogen protection, after melting evenly at 615-625°C, cool down to 420-450°C and keep the temperature constant for 1-2 hours, then cast and extrude to obtain an alloy solder; The alloy solder and the soldering flux are extruded into a single-core solder wire with a diameter of 8-10 mm by a hydraulic press, and then drawn to a single-core solder wire with a diameter in the range of 0.25-0.3 mm by a wire drawing machine.

[0027] The method for preparing the single-core solder wire adopted in this application can reduce the defect rate of the single-core solder wire and reduce the occurrence of the problem of broken cores in the single-core solder wire.

[0028] To sum up, this application at least includes the following beneficial technical effects:

[0029] (1) The single-core solder wire in this application includes an alloy solder layer and a soldering flux layer arranged in sequence from outside to inside. Among them, the alloy solder layer is made of Bi (bismuth), Cu (copper), Ag (silver), Ti (titanium), Zn (zinc), Ni (nickel), Sn (tin)-Be (beryllium)-Sb (antimony) ternary alloy and Sn (tin) with a specific ratio. The combined action of the elements with specific ratios is beneficial to improving the oxidation resistance and low-temperature brittleness of the alloy solder layer, and 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 soldering flux layer is made of modified rosin, organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent with a specific ratio. This soldering flux layer can help remove impurities such as oxide films and oil stains on the surface of the metal to be soldered, 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 soldered after melting, ensuring that the solder joint is firm and reliable.

[0030] (2) In this 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

[0031] Figure 1 is a schematic structural diagram of the single-core solder wire of this application.

[0032] Description of the reference numerals:

[0033] 1. Alloy solder layer; 2. Soldering flux layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present application will be further described below in combination with specific experiments.

[0035] Example

[0036]

Example 1

[0037] A single-core solder wire includes an alloy solder layer 1 and a flux layer 2 arranged in sequence from outside to inside. The weight ratio of the flux layer 2 in the single-core solder wire is 2.2%. 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. In the Sn-Be-Sb ternary alloy, the weight percentage of Be is 2.3%, the weight percentage of Sb is 1.5%, Sn is the balance, and the preparation method of the Sn-Be-Sb ternary alloy includes the following steps:

[0038] S1. After melting Sn in an inert gas environment at 250°C, heating it to 350°C, adding Sb and Be, stirring and melting evenly, and then cooling to 220°C and holding for 0.5 h to obtain a molten material;

[0039] S2. Pour the molten material into a mold, cool it to obtain the Sn-Be-Sb ternary alloy.

[0040] The preparation raw materials of the flux layer 2 include 55 kg of modified rosin, 4.5 kg of organic acid, 3.2 kg of diethanolamine, 0.1 kg of Tween 20, 1.5 kg of benzaldehyde, 0.2 kg of benzotriazole, and 15 kg of absolute ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin (Senya SY-Q1), and the weight ratio of 145 rosin pentaerythritol ester to 210 rosin modified phenolic resin is 3:1. The organic acid includes malic acid and adipic acid, and the weight ratio of malic acid to adipic acid is 1:1.

[0041] In this example, the preparation method of the single-core solder wire includes the following steps:

[0042] After heating and melting the modified rosin, adding a mixed solution of organic acid, diethanolamine, Tween 20, benzaldehyde, benzotriazole, and absolute ethanol, and mixing evenly to obtain a flux, and keeping it at a constant temperature of 145°C for standby;

[0043] Put Sn, Bi, Cu, Ag, Ti, Zn, Ni, and Sn-Be-Sb ternary alloy into a vacuum melting furnace, melt and mix evenly at 615°C under nitrogen protection, then cool to 450°C, keep the temperature constant for 1 h, and then cast and extrude to obtain an alloy solder;

[0044] The alloy solder and the soldering flux are extruded by a hydraulic press into a single-core solder wire with a diameter of 10 mm, and then drawn by a wire drawing machine to a single-core solder wire with a diameter of 0.3 mm.

[0045]

Example 2

[0046] A single-core solder wire includes an alloy solder layer 1 and a soldering flux layer 2 arranged in sequence from outside to inside, and the weight ratio of the soldering flux layer 2 in the single-core solder wire is 1.1%. The alloy solder layer 1 is made of 15 wt% Bi, 0.5 wt% Cu, 3 wt% Ag, 0.05 wt% Ti, 0.05 wt% Zn, 0.2 wt% Ni, 0.55 wt% Sn-Be-Sb ternary alloy and the balance Sn. In the Sn-Be-Sb ternary alloy, the weight percentage of Be is 2.8%, the weight percentage of Sb is 2.0%, Sn is the balance, and the preparation method of the Sn-Be-Sb ternary alloy includes the following steps:

[0047] S1. After melting Sn in an inert gas environment at 240°C, raising the temperature to 360°C, adding Sb and Be, stirring and melting evenly, and then cooling to 200°C and holding for 1 h to obtain a molten material;

[0048] S2. Pour the molten material into a mold and cool to obtain the Sn-Be-Sb ternary alloy.

[0049] The preparation raw materials of the soldering flux layer 2 include 60 kg of modified rosin, 5.5 kg of organic acid, 3.6 kg of triethanolamine, 0.15 kg of Tween 60, 2.5 kg of benzaldehyde, 0.3 kg of benzothiazole, and 20 kg of absolute ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin modified phenolic resin (Senya SY-Q1), and the weight ratio of 145 rosin pentaerythritol ester to 210 rosin modified phenolic resin is 4:1. The organic acid includes malic acid and adipic acid, and the weight ratio of malic acid to adipic acid is 1.5:1.

[0050] In this example, the preparation method of the single-core solder wire includes the following steps:

[0051] After heating and melting the modified rosin, add a mixed solution of organic acid, triethanolamine, Tween 60, benzaldehyde, benzothiazole, and absolute ethanol, and after mixing evenly, obtain the soldering flux and keep it at a constant temperature of 155°C for standby;

[0052] Put Sn, Bi, Cu, Ag, Ti, Zn, Ni, and Sn-Be-Sb ternary alloy into a vacuum melting furnace, under nitrogen protection, melt evenly at 625°C, then cool to 420°C, hold for 2 h, and then cast and extrude to obtain the alloy solder;

[0053] The alloy solder and the flux are extruded 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.

[0054]

Example 3

[0055] A single-core solder wire, which is different from

Example 1

[0056] 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.

[0057]

Example 4

[0058] A single-core solder wire, which is different from

Example 1

[0059] The alloy solder layer 1 is made of 15 wt% Bi, 1.0 wt% Cu, 2.5 wt% Ag, 0.25 wt% Ti, 0.2 wt% Zn, 0.2 wt% Ni, 0.85 wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0060] Comparative Example

[0061]

Comparative Example 1

[0062] A single-core solder wire, which is different from

Example 1

[0063] In this comparative example, the alloy solder layer is made of 10 wt% Bi, 2.5 wt% Cu, 4.0 wt% Ag, 0.5 wt% Ti, 1.0 wt% Zn, 0.4 wt% Ni, 0.15 wt% Sn-Be-Sb ternary alloy and the balance Sn.

[0064]

Comparative Example 2

[0065] A single-core solder wire, which is different from

Example 1

[0066] 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.

[0067]

Comparative Example 3

[0068] A single-core soldering wire, which is different from [Embodiment 1] in that: in the flux layer 2, the ratio of each component is different.

[0069] In this comparative example, the raw materials for preparing the flux layer 2 include 65 kg of modified rosin, 8.5 kg of organic acid, 6.8 kg of diethanolamine, 0.3 kg of Tween 20, 0.5 kg of benzaldehyde, 0.1 kg of benzotriazole, and 15 kg of absolute ethanol. Among them, the modified rosin includes 145 rosin pentaerythritol ester and 210 rosin-modified phenolic resin (Senya SY-Q1), and the weight ratio of 145 rosin pentaerythritol ester to 210 rosin-modified phenolic resin is 1:1. The organic acid includes malic acid and adipic acid, and the weight ratio of malic acid to adipic acid is 1:3.

[0070] Performance detection test

[0071] 1. Ductility: After the single-core soldering wires prepared in each example and comparative example are respectively left standing in an environment of 5°C and -10°C for 48 hours, the ductility test is carried out according to ASTM E290 "Standard Test Method for Bend Test for Testing Ductility of Materials". The bending angles are 90° and 45° respectively. Passing the test means no cracking, otherwise the test fails. Among them, the better the ductility, the better the performance of the single-core soldering wire in resisting low-temperature brittleness.

[0072] 2. Spreading coefficient: Refer to GB / T 11364-89 "Test Method for Spreading and Gap-Filling Properties of Brazing Filler Metals" to detect the spreading coefficients of the single-core soldering wires prepared in each example and comparative example. The spreading substrate is a pure copper thin plate with a thickness of 0.2 mm. The test temperature is 400°C and the time is 10 s. The larger the spreading coefficient, the better the wettability of the single-core soldering wire, which is beneficial to improving the welding strength of the solder joint.

[0073] 3. Tensile strength of solder joint: Use the single-core soldering wires prepared in each example and comparative example to prepare test specimens. The other conditions of the test specimens are kept the same. Refer to GB / T 2651-2023 "Destructive Tests on Welds in Metallic Materials Transverse Tensile Test" to test the tensile strength of the solder joints of the test specimens. The test temperature is 25°C.

[0074] Table 1

[0075]

[0076] Table 2

[0077] Specimen 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

[0078] It can be seen from the detection data in combination with Example 1, Comparative Examples 1-3 and Tables 1-2 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 and decreased, which is not conducive to the processing of the single-core solder wire in a low-temperature environment. The composition of the flux layer affects the spreadability of the alloy solder and the welding strength of the solder joints.

[0079] It can be seen from the detection data in combination with Example 1, Examples 3-4 and Tables 1-2 that by optimizing the ratio of each component in the alloy solder layer, the low-temperature brittleness of the alloy solder layer can be further improved, which is beneficial to the winding of the single-core solder wire in a lower-temperature environment, and can also improve the stability of the solder joints in a lower-temperature environment.

[0080] This specific implementation manner is only an interpretation of this application, and it does not limit this application. After reading this specification, those skilled in the art can make modifications to this specific implementation manner without creative contributions as needed, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A single-core solder wire, characterized in that: It includes an alloy solder layer (1) and a flux layer (2) arranged from outside to inside in sequence. 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. The preparation raw materials of 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, wherein: The preparation method of the Sn - Be - Sb ternary alloy includes the following steps: S1. After melting Sn in an inert gas environment at 240 - 250°C, raise the temperature to 350 - 360°C, add Sb and Be, stir and melt evenly, then cool down to 200 - 220°C and keep warm for 0.5 - 1h to obtain a molten material; S2. Pour the molten material into a mold and cool to obtain the Sn - Be - Sb ternary alloy.

3. A single-core solder wire according to claim 1, characterized in that: The modified rosin includes pentaerythritol ester of rosin and rosin modified phenolic resin, and the weight ratio of the pentaerythritol ester of rosin and rosin modified phenolic resin is (3 - 4):

1.

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

5. A single-core solder wire according to claim 1, characterized in that: The surfactant adopts Tween 20 or Tween 60.

6. The single-core solder wire according to claim 1, wherein: The antioxidant adopts aromatic aldehyde, and the corrosion inhibitor adopts at least one of benzotriazole and benzothiazole.

7. A single-core solder wire according to claim 1, characterized in that: The organic solvent adopts absolute ethanol.

8. A single-core solder wire according to claim 1, characterized in that: The weight proportion of the flux layer is 1.1 - 2.2%.

9. A preparation method of a single-core solder wire according to any one of claims 1-8, characterized in that, It includes the following steps: After heating and melting the modified rosin, add a mixed solution of organic acid, organic amine, surfactant, antioxidant, corrosion inhibitor and organic solvent, mix evenly to obtain a flux, and keep it at a constant temperature of 145 - 155°C for standby; Put Sn, Bi, Cu, Ag, Ti, Zn, Ni, Sn - Be - Sb ternary alloy into a vacuum melting furnace, melt evenly under nitrogen protection at 615 - 625°C, then cool down to 420 - 450°C, keep the temperature constant for 1 - 2h, and then cast and extrude to obtain an alloy solder; Extrude the alloy solder and the flux into a single - core solder wire with a diameter of 8 - 10mm through a hydraulic press, and then draw it to a single - core solder wire with a diameter range of 0.25 - 0.3mm by a wire drawing machine.

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