Manganese-copper and red-copper dual-applicable tin-based solder and application thereof

Abstract

The invention discloses a tin-based solder applicable to manganese copper and red copper. The tin-based solder comprises the following components in percentage by mass: 0.1-3 wt% of Ag, 0.5-1 wt% of Cu, 0.5-2 wt% of Ga, 1-4 wt% of In and the balance of Sn. The application of the manganin and red copper dual-application tin-based solder in manganin and red copper tinning solves the technical problems that the tinning process of traditional solder components is difficult to complete at a time, red copper tinning needs to be completed at a high temperature, and then manganin surface tinning needs to be achieved at a relatively low temperature.

Description

Technical Field

[0001] The invention belongs to the field of metal material processing, and in particular relates to a tin-based solder that is dual-applicable to manganese copper and red copper and an application thereof. Background Art

[0002] Shunts are commonly used current sampling components capable of measuring DC current. They are based on the principle that DC current flowing through a resistor generates a voltage across the resistor. By measuring the voltage drop across the shunt, the actual current flowing through the shunt can be calculated. Precision shunt resistors consist of a resistor element and a busbar. The resistor element is made of manganese copper plate with a low temperature coefficient (temperature coefficient <20ppm), while the busbar is made of copper plate with good thermal and electrical conductivity. In use, the manganese copper and copper elements are connected together as a single component and tinned.

[0003] Manganese copper is a precision resistance alloy primarily composed of copper and manganese. Its high Mn content reduces its surface energy, allowing a stable manganese dioxide film to form on its surface. When tinned, the solder's wetting angle increases by 30-40%, placing special demands on the tinning process. Generally speaking, when tinning manganese copper with tin-based solder, the temperature needs to be controlled between 270-300°C. This allows the molten solder to have the appropriate fluidity and surface tension, resulting in a smooth coating without fins. However, tinning copper requires a temperature of 330-350°C. Higher temperatures effectively reduce solder viscosity, thus avoiding defects such as coating shrinkage and pinholes caused by insufficient temperature.

[0004] It can be seen that the difference in the characteristics of the two materials and the contradiction in temperature sensitivity during welding make it difficult for traditional solder compositions to complete the tin plating process in one go. It is necessary to first complete the tin plating of copper at a high temperature, and then tin the surface of manganese copper at a relatively low temperature. It is worth noting that although the tin-silver-copper solder used in the existing hot-dip plating process can meet the 340°C process requirements of copper, it will produce grain boundary segregation when used for manganese copper, and high temperature will aggravate the coarsening of the manganese copper matrix grains (the average grain size increases by 50-100μm), resulting in a 15%-20% decrease in the tensile strength of the material. At the same time, it cannot meet the flatness requirements of the tin layer on the manganese copper surface. Summary of the Invention

[0005] Based on the above technical problems, the present invention provides a tin-based solder with temperature adaptability. The solder can be used to complete the tin plating process on the surface of copper and manganese copper in one go, saving process costs while meeting performance requirements.

[0006] The specific scheme of the present invention is as follows:

[0007] One of the purposes of the present invention is to provide a manganese copper and copper dual-applicable tin-based solder, which comprises, by mass percentage, 0.1-3wt% Ag, 0.5-1wt% Cu, 0.5-2wt% Ga, 1-4wt% In, and the balance Sn.

[0008] Preferably, the composition includes, by mass percentage: Ag 1.5-2.5wt%, Cu 0.6-0.9wt%, Ga 1.0-1.5wt%, In 2-3wt%, and the balance Sn.

[0009] Preferably, the atomic ratio of Ga to In is 1:1.7 to 2.3.

[0010] Preferably, the preparation method of the tin-based solder comprises: adding Sn, Ag, Cu, Ga, and In in proportion under a protective atmosphere, performing gradient melting, stirring evenly, and keeping warm for 30 to 60 minutes to obtain the solder.

[0011] Preferably, the protective atmosphere is argon.

[0012] The second object of the present invention is to provide the application of the above-mentioned tin-based solder in tin plating of manganese copper and red copper.

[0013] Preferably, the tin-based solder is used in tin plating of electronic components containing both manganese copper and red copper.

[0014] Preferably, the connection method is hot-dip galvanizing; more preferably, the temperature of the hot-dip galvanizing is 320-340°C.

[0015] Preferably, the hot-dip coating method comprises the following steps:

[0016] S1. Under a protective atmosphere, add Sn, Ag, Cu, Ga, and In in proportion, carry out gradient melting, stir evenly, and keep warm to obtain a molten tin-based solder; S2. Preheat the substrate to 280-300°C; S3. Immerse the preheated substrate in the molten tin-based solder alloy at a dipping temperature of 320-340°C for 1-3s, and cool; the substrate includes manganese copper and / or red copper.

[0017] Preferably, in S2, the cooling rate is 10-15°C / s.

[0018] The beneficial effects of the present invention are:

[0019] The present invention provides a tin-based solder that is dual-applicable to manganese copper and red copper. By adding Ga / In as composite additives to a traditional Sn-Ag-Cu solder alloy, the liquidus temperature of the alloy is significantly reduced to 216-219°C through a synergistic effect.

[0020] The tin-based solder described in the present invention can complete the tin plating process on the surfaces of red copper and manganese copper in one go. At a relatively high tin plating temperature, a smooth coating without sharp edges can be obtained on the surface of manganese copper. The solder is particularly suitable for electronic components that contain both manganese copper and red copper, such as tin plating of shunt resistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the DSC curve of the manganese copper and copper dual-applicable tin-based solder described in Example 1;

[0022] Figure 2 These are SEM images of the manganese copper surface coating and the red copper surface coating obtained in Example 1, wherein (a) is the manganese copper surface coating and (b) is the red copper surface coating. DETAILED DESCRIPTION

[0023] Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0024] Example 1

[0025] A tin-based solder suitable for both manganese copper and red copper comprises, by weight percentage, 2.5 wt% Ag, 0.9 wt% Cu, 1.5 wt% Ga, 2.0 wt% In, and the balance Sn, wherein the atomic ratio of Ga:In is approximately 1:1.8.

[0026] The DSC curve of the tin-based solder described in this embodiment is as follows: Figure 1 As shown, it can be seen that adding Ga / In as a composite additive to the traditional Sn-Ag-Cu solder alloy can significantly reduce the alloy liquidus temperature to 216-219°C.

[0027] The tin-based solder of this embodiment is used in the simultaneous tinning of manganese copper and red copper, and the specific method includes:

[0028] S1. Under argon protection, Sn, Ag, Cu, Ga, and In are added to a melting furnace in proportion and smelted in a gradient manner at a melting temperature of 325°C. After stirring evenly, the mixture is kept warm for 55 minutes to obtain a molten tin-based solder.

[0029] S2. Clean the surface of MnCu54 manganese-copper alloy and T2 copper substrate, and preheat the manganese-copper substrate to 295°C;

[0030] S3. Immerse the preheated manganese copper and copper into a molten tin-based solder alloy at a dipping temperature of 335°C for 2 seconds, and then cool at a gradient cooling rate of 14°C / s.

[0031] The wetting angles of the tin-based solder described in this embodiment on manganese copper and copper substrates were tested and were 32° and 28°, respectively.

[0032] The tinned joint obtained in this embodiment has good fatigue resistance, wherein the SEM images of the manganese copper surface coating and the copper surface coating are shown as follows: Figure 2 As shown in (a) and (b), it can be seen that the coating thickness is uniform and there are no coarse grains in the interface IMC layer.

[0033] Example 2

[0034] A tin-based solder suitable for both manganese copper and red copper comprises, by weight percentage, 2.0 wt% Ag, 0.8 wt% Cu, 1.0 wt% Ga, 2.5 wt% In, and the balance Sn, wherein the atomic ratio of Ga:In is approximately 1:2.

[0035] The tin-based solder described in this embodiment is used in the tin plating of manganese copper, and the specific method includes:

[0036] S1. Under argon protection, Sn, Ag, Cu, Ga, and In are added to a melting furnace in proportion, the melting temperature is controlled to 330°C, and the mixture is stirred evenly and kept warm for 45 minutes to obtain a molten tin-based solder;

[0037] S2. Clean the surface of the MnCu54 manganese copper alloy substrate and preheat the MnCu54 manganese copper substrate to 290°C.

[0038] S3. Immerse the preheated MnCu54 manganese copper substrate in the molten tin-based solder alloy, control the immersion temperature to 330°C, the immersion time to 2s, and then cool it at a gradient cooling rate of 12°C / s.

[0039] The wetting angle of the tin-based solder described in this embodiment on manganese copper was tested. The results showed that the wetting angle of the alloy on manganese copper was 30°, the fatigue resistance of the obtained tin-plated joint was significantly improved, the coating thickness was uniform, and the interface IMC layer had no coarse grains.

[0040] Example 3

[0041] A tin-based solder suitable for both manganese copper and red copper comprises, by weight percentage, 2.0 wt% Ag, 0.8 wt% Cu, 1.0 wt% Ga, 2.5 wt% In, and the balance Sn, wherein the atomic ratio of Ga:In is approximately 1:2.

[0042] The tin-based solder described in this embodiment is used in tinning of copper, and the specific method includes:

[0043] S1. Under argon protection, Sn, Ag, Cu, Ga, and In are added to a melting furnace in proportion, the melting temperature is controlled to 335°C, and the mixture is stirred evenly and kept warm for 50 minutes to obtain a molten tin-based solder.

[0044] S2. Clean the surface of the T2 copper substrate and preheat the T2 copper substrate to 285°C.

[0045] S3. Immerse the preheated T2 copper into the molten tin-based solder alloy, control the immersion temperature to 325°C, the immersion time to 2s, and then cool it at a gradient cooling rate of 13°C / s.

[0046] The wetting angle of the tin-based solder described in this embodiment on copper was tested. The results showed that the wetting angle of the solder on the T2 copper substrate was 25°. The obtained tin-plated joint had excellent fatigue resistance, uniform coating thickness, and no coarse grains in the interface IMC layer.

[0047] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A tin-based solder suitable for both manganese copper and copper, characterized in that: The composition includes, by mass percentage, 0.1-3 wt% of Ag, 0.5-1 wt% of Cu, 0.5-2 wt% of Ga, 1-4 wt% of In, and the balance of Sn.

2. The manganese copper and copper dual-applicable tin-based solder according to claim 1, characterized in that: The composition includes, by mass percentage, 1.5-2.5 wt% of Ag, 0.6-0.9 wt% of Cu, 1.0-1.5 wt% of Ga, 2-3 wt% of In, and the balance of Sn.

3. The manganese copper and copper dual applicable tin-based solder according to claim 1 or 2, characterized in that: The atomic ratio of Ga to In is 1:1.7 to 2.

3.

4. The manganese copper and copper dual applicable tin-based solder according to claim 1 or 2, characterized in that: The preparation method of the tin-based solder comprises: adding Sn, Ag, Cu, Ga and In in proportion under a protective atmosphere, performing gradient melting, stirring evenly, and keeping the temperature for 30 to 60 minutes to obtain the solder.

5. Use of the manganese copper and copper dual-applicable tin-based solder according to any one of claims 1 to 4 in tin plating of manganese copper and copper.

6. The use according to claim 5, characterized in that Application in tinning of electronic components containing both manganese copper and copper.

7. The use according to claim 5, characterized in that The tinning method is hot-dip tinning.

8. The use according to claim 7, characterized in that The temperature of hot dipping is 320-340℃.

9. The use according to claim 7, characterized in that The hot-dip plating method includes the following steps: S1. In a protective atmosphere, Sn, Ag, Cu, Ga, and In are added in proportion, gradient smelting is performed, stirring is performed, and heat preservation is performed to obtain a molten tin-based solder; S2. The substrate is preheated to 280-300°C; S3. The preheated substrate is immersed in the molten tin-based solder alloy at a dipping temperature of 320-340°C and a dipping time of 1-3s, and then cooled; the substrate includes manganese copper and / or copper.

10. The use according to claim 9, characterized in that In S2, the cooling rate is 10-15°C / s.

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