A method for preparing high-tin thin strip

Abstract

The invention relates to the field of metallurgical casting, and in particular to a method for preparing a high-tin thin strip. In this scheme, a thin strip alloy solder to be processed is first passed through a soldering agent tank, a layer of solder is adhered on the surface of the thin strip alloy solder, and then the thin strip alloy solder is heated through a heating electrode to a temperature of 350-450 DEG C, and then passed through a composite tin roller, under the action of the temperature of the heated thin strip solder itself, the tin metal on the surface of the composite tin roller is melted, the solder removes the oxide film on the surface of the solder alloy, and the molten tin metal and the solder alloy undergo a metallurgical reaction under the pressure of the composite tin roller, so that the tin metal is evenly coated on the surface of the solder strip, thereby preparing a tin thin strip solder, and without affecting the processing performance of the solder, the tin content is increased, and the solder is prevented from being easily cracked during the rolling process, thereby realizing the preparation of the high-tin thin strip solder.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical casting, and particularly to a method for preparing a high-tin thin strip. Background Art

[0002] A filler metal is a filler added within or beside the gap for realizing the bonding of two materials. In the existing process of preparing filler metals, tin element is a commonly used additive component in hard filler metals, which can reduce the melting temperature of the filler metal and improve the quality of the brazing seam. However, when the tin content reaches a certain proportion, the excessive tin content will deteriorate the processing performance of the filler metal, making the filler metal prone to fracture. For example, when adding tin element to silver-copper filler metal, the content of tin element can reach up to about 5.5 wt.% (weight percentage) at most. Adding 4 wt.% tin element to copper-phosphorus filler metal can reduce the melting temperature by more than one hundred degrees and form a brazing seam with good performance. This is the best filler metal to replace copper-phosphorus-silver, which can reduce the preparation cost of the filler metal. However, when the tin content in the filler metal exceeds 1 wt.%, with the increase of the tin content, the brittle phase of Cu 3 P in the filler metal also gradually increases, making the filler metal prone to cracking during the rolling process, resulting in the situation that high-tin thin strips of copper-phosphorus and copper-phosphorus-silver filler metals cannot be prepared by the common filler metal processing technology. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a high-tin thin strip that can avoid cracking of the filler metal during the rolling process.

[0004] The basic solution provided by the present invention: A method for preparing a high-tin thin strip, comprising the steps of:

[0005] S1: Adhere a layer of brazing flux on the surface of the filler metal alloy thin strip;

[0006] S2: Heat the filler metal alloy thin strip through a heating electrode to make the temperature of the filler metal alloy thin strip reach 350 - 450 °C;

[0007] S3: Pass the heated filler metal alloy thin strip through a composite tin roller for rolling, so that the tin metal reacts metallurgically with the filler metal alloy to prepare a high-tin thin strip filler metal.

[0008] The principle and advantages of the present invention are as follows: In GB / T 10046-2018, the silver content in BAg30CuZn filler metal is 30 wt.%, and the liquidus temperature of this filler metal is 765 °C; the silver content in BAg35CuZn filler metal is 35 wt.%, and the liquidus temperature of this filler metal is 755 °C. Silver belongs to precious metals. Increasing the silver content by 5 wt.% reduces the liquidus temperature by 10 °C. The tin content in BAg30CuZnSn is 1.5 - 2.5 wt.%, and its liquidus temperature is 755 °C. Therefore, increasing the tin content by 1.5 - 2.5 wt.% can achieve the same effect as increasing the silver content by 5 wt.% in terms of reducing the melting temperature of the filler metal. However, as the tin content in the filler metal increases, when the tin content in the filler metal exceeds 5.5 wt.%, the filler metal is prone to cracking during the rolling process and is difficult to be processed into thin strips.

[0009] In this solution, first, the thin strip alloy filler metal to be processed passes through a flux bath, and a layer of flux adheres to its surface. Then, it passes through heating electrodes to heat the thin strip alloy filler metal to a temperature of 350 - 450 °C. Next, through a composite tin roll, under the action of the temperature of the heated thin strip filler metal itself, the tin metal on the surface of the composite tin roll melts. The flux removes the oxide film on the surface of the filler metal alloy, and the molten tin metal and the filler metal alloy undergo a metallurgical reaction under the pressure of the composite tin roll, enabling the tin metal to be evenly coated on the surface of the filler metal strip, thereby preparing a high-tin thin strip filler metal. Through experimental testing, the high-tin thin strip filler metal prepared by this solution has a thickness of 0.08 - 0.3 mm, a width of 10 - 200 mm, and a tin content of 6 - 60 wt.%. Without affecting the processing performance of the filler metal, it not only increases the tin content but also avoids the situation where the filler metal is prone to cracking during the rolling process, realizing the preparation of the high-tin thin strip filler metal.

[0010] Further, it also includes S4: winding the processed high-tin thin strip filler metal through a winding device. Winding the processed high-tin thin strip filler metal through a winding device can effectively control the speed of the high-tin alloy thin strip passing through the composite tin roll, thereby indirectly controlling the tin content of the high-tin thin strip filler metal.

[0011] Further, in step S1, a flux bath is used to hold the flux, and the flux components are 35% ZnCl 2 、15% NH 4 Cl, 5% NaCl, and 45% water.

[0012] Further, the heating electrodes in step S2 adopt copper electrodes. Copper electrodes have excellent electrical conductivity and thermal conductivity, and low cost, which can reduce the preparation cost while ensuring the heating efficiency.

[0013] Further, the composite tin roll in step S3 is of composite material, with a steel roll in the middle and a high-purity tin sleeve on the outside. The purity of the tin sleeve is 99.99%, and the thickness is 5 mm - 20 mm.

[0014] Further, the composite tin roller in the step S3 includes an upper tin roller and a lower tin roller, and a metallurgical reaction occurs to the solder alloy thin strip under the pressure between the upper tin roller and the lower tin roller. Under the action of the temperature of the solder alloy thin strip itself, the tin metal on the surfaces of the upper and lower composite tin rollers melts, and the flux can remove the oxide film on the surface of the solder alloy. Then, the molten tin metal can undergo a metallurgical reaction with the solder alloy under the pressure of the upper tin roller and the lower tin roller, so that the tin metal is evenly coated on the surface of the solder strip, and a high-tin thin strip solder is prepared.

[0015] Further, a support roller is longitudinally arranged on the composite tin roller in the step S3, and the support roller is used to support the composite tin roller to prevent the composite tin roller from deforming and improve the thickness and accuracy of the coated tin layer.

[0016] Further, in the step S3, the pressure range between the upper tin roller and the lower tin roller is 100 - 1000 N, and the winding speed range of the winding device is 1 - 10 m / min; different tin content high-tin thin strips can be prepared by controlling the pressure between the upper tin roller and the lower tin roller and the speed of the high-tin alloy thin strip passing through the upper tin roller and the lower tin roller. Description of the Drawings

[0017] Figure 1 It is the flowchart of the steps of the first embodiment of the present invention.

[0018] Figure 2 It is the line scan diagram of the copper-phosphorus-tin solder of the first embodiment of the present invention.

[0019] Figure 3 It is the surface scan diagram of the copper-phosphorus-tin solder of the first embodiment of the present invention.

[0020] Figure 4 It is the line scan diagram of the copper-phosphorus-silver-tin solder of the first embodiment of the present invention.

[0021] Figure 5 It is the surface scan diagram of the copper-phosphorus-silver-tin solder of the first embodiment of the present invention. Detailed Description of the Embodiment

[0022] The following is further detailed through specific embodiments:

[0023] The specific implementation process is as follows:

[0024] Embodiment 1

[0025] Embodiment 1 is basically as shown in the appendix, and a method for preparing a high-tin thin strip includes the steps: Figure 1 S1: The solder alloy thin strip to be processed first passes through the flux tank, and a layer of flux adheres to the surface of the solder alloy thin strip;

[0026] ​

[0027] S2: Heat the solder alloy thin strip through a heating electrode to make the temperature of the solder alloy thin strip reach 350 - 450 °C;

[0028] S3: Pass the heated solder alloy thin strip through a composite tin roll for rolling, so that the tin metal reacts metallurgically with the solder alloy to prepare a high - tin thin strip solder;

[0029] S4: Wind up the processed high - tin thin strip solder through a winding device.

[0030] Specifically, the solder alloy thin strip first passes through a flux bath, and a layer of flux adheres to the surface of the solder alloy thin strip. In this embodiment, the flux components contained in the flux bath are 35% ZnCl 2 、15% NH 4 Cl, 5% NaCl and 45% water. Then, the thin strip alloy solder is heated through a heating electrode. In this embodiment, a copper electrode is used for heating, so that the temperature of the thin strip alloy solder reaches 350 - 450 °C and enters the composite tin roll.

[0031] The composite tin roll in this solution is made of composite materials. The middle is a steel roll, and the outside is a high - purity tin sleeve. The purity of the tin sleeve is 99.99%, and the thickness is 5 mm - 20 mm. The composite tin roll includes an upper tin roll and a lower tin roll. The solder alloy thin strip undergoes a metallurgical reaction under the pressure between the upper tin roll and the lower tin roll. Under the temperature effect of the solder alloy thin strip itself, the tin metal on the surfaces of the upper and lower composite tin rolls melts. The flux can remove the oxide film on the surface of the solder alloy, and then the molten tin metal can react metallurgically with the solder alloy under the pressure of the upper and lower tin rolls, so that the tin metal is evenly coated on the surface of the solder strip to prepare a high - tin thin strip solder. One end of the high - tin thin strip solder is fixedly connected to the winding device, and the processed high - tin thin strip solder is wound up through the winding device.

[0032] In addition, as shown in Table 1, the pressure range between the upper tin roll and the lower tin roll in this embodiment is 100 - 1000 N, and the winding speed range of the winding device is 1 - 10 m / min; by controlling the pressure between the upper tin roll and the lower tin roll and the speed of the high - tin alloy thin strip passing through the upper and lower tin rolls, a high - tin thin strip with a thickness of 0.08 - 0.3 mm, a width of 10 - 200 mm, and a tin content of 6 - 60 wt.% can be prepared.

[0033] Table 1 Pressure - speed - tin content comparison table

[0034] Rolling pressure (N) Rolling speed (m / min) Width of thin strip solder (mm) Tin content of thin strip solder (wt.%) 100 10.0 10 6 130 8.5 10 20 170 6.9 10 40 220 5.2 10 60 350 7.4 100 6 470 6.1 100 20 610 5.3 100 40 820 4.3 100 60 520 4.9 200 6 710 3.4 200 20 880 1.9 200 40 1000 1.0 200 60

[0035] After experiments, the experimental data of this solution are as follows. The high - tin thin strip solder prepared by this solution, such as Figure 2As shown, a microstructural diagram of a copper-phosphorus-tin solder (the pressure of the composite tin roller is 600 N and the speed of the thin strip passing through the tin roller is 2 m / min). The layers on both sides are tin layers, and the middle layer is a copper-phosphorus layer, with the tin content reaching 55.79 wt%.

[0036] As Figure 3 shown, a line scan diagram of a copper-phosphorus-tin solder (the pressure of the composite tin roller is 600 N and the speed of the thin strip passing through the tin roller is 2 m / min). The layers on both sides are tin layers, and the middle layer is a copper-phosphorus layer, with the tin content reaching 55.79 wt%.

[0037] As Figure 4 shown, a line scan diagram of a copper-phosphorus-silver-tin solder (the pressure of the composite tin roller is 400 N and the speed of the thin strip passing through the tin roller is 5 m / min). The layers on both sides are tin layers, and the middle layer is a copper-phosphorus layer.

[0038] As Figure 5 shown, a line scan diagram of a copper-phosphorus-silver-tin solder (the pressure of the composite tin roller is 400 N and the speed of the thin strip passing through the tin roller is 5 m / min). The layers on both sides are tin layers, and the middle layer is a copper-phosphorus layer, with the tin content reaching 23.82 wt%.

[0039] Example 2

[0040] The difference between Example 2 and Example 1 is only that a support roller is longitudinally provided on the composite tin roller in step S3. The support roller is used to support the composite tin roller to prevent the composite tin roller from deforming and improve the thickness and accuracy of the coated tin layer.

[0041] The above are only the embodiments of the present invention. Common general knowledge such as specific structures and characteristics in the solutions is not described in detail here. Those of ordinary skill in the art know all the common general knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the existing technologies in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, complete and implement this solution in combination with their own abilities. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. A method for preparing a high-tin thin strip, characterized in that: Includes steps: S1: A layer of brazing flux is adhered to the surface of the brazing alloy strip; S2: heating the solder alloy ribbon by heating the electrode to make the temperature of the solder alloy ribbon reach 350-450°C; S3: rolling the heated solder alloy thin strip through a composite tin roller, so that the tin metal and the solder alloy undergo a metallurgical reaction to prepare a high-tin thin strip solder; The composite tin roller in step S3 is made of composite material, with a steel roller in the middle and a high-purity tin sleeve on the outside.

2. The method for preparing a high-tin thin strip according to claim 1, characterized in that: It also includes S4: high-tin thin strip solder that is coiled by a coiling device.

3. The method for preparing a high-tin thin strip according to claim 2, characterized in that: In step S1, a flux tank is used to contain the flux, and the flux composition is 35% ZnCl2, 15% NH4Cl, 5% NaCl and 45% water.

4. The method for preparing a high-tin thin strip according to claim 3, characterized in that: The heating electrode in step S2 is a copper electrode.

5. The method for preparing a high-tin thin strip according to claim 4, characterized in that: The purity of the tin sleeve is 99.99% and the thickness is 5mm-20mm.

6. The method for preparing a high-tin thin strip according to claim 5, characterized in that: The composite tin roller in step S3 comprises an upper tin roller and a lower tin roller, and the solder alloy thin strip undergoes a metallurgical reaction due to the pressure between the upper tin roller and the lower tin roller.

7. The method for preparing a high-tin thin strip according to claim 6, characterized in that: The composite tin roller in step S3 is also longitudinally provided with a supporting roller, and the supporting roller is used to support the composite tin roller to prevent the composite tin roller from deforming.

8. The method for preparing a high-tin thin strip according to claim 6, characterized in that: In step S3, the pressure between the upper tin roller and the lower tin roller is in the range of 100-1000N, and the winding speed of the winding device is in the range of 1-10m / min; high-tin thin strips with different tin contents can be prepared by controlling the pressure between the upper tin roller and the lower tin roller and the speed at which the high-tin alloy thin strip passes through the upper tin roller and the lower tin roller.

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