Tin soldering process of rare earth permanent magnet assembly

Abstract

The invention discloses a tin soldering process of a rare earth permanent magnet assembly, which comprises the following steps of: accurately positioning a spraying area of a magnet welding surface by using a visual positioning mechanism, positioning the spraying area at the central position of the magnet welding surface, and spraying solder paste on the spraying area by using a spraying machine, the use amount of the solder paste in each 1 mm < 2 > of the spraying area is 0.09-0.11 mg; arranging and placing a plurality of magnets on a magnetic conductive jig, pressing all the magnets by using a hot pressing head of hot pressing equipment, and laterally pushing all the magnets by using a push rod to press all the magnets together; and then a hot-pressing head of the hot-pressing equipment is used for heating so as to carry out hot-pressing on all the magnets, the solder paste is melted, then the hot-pressing equipment stops heating, compressed air is introduced to cool the hot-pressing head and the magnets, and the solder paste is rapidly solidified to form welding. According to the invention, the magnet is assembled by adopting a tin soldering process, the assembling speed is high, glue overflow is avoided, and the assembled rare earth permanent magnet assembly has extremely high structural stability and high temperature and humidity resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of magnet processing and preparation, and particularly relates to a soldering process for a rare earth permanent magnet component. Background Art

[0002] Rare earth permanent magnet components are assembled from multiple permanent magnets, such as Halbach magnet components. Currently, traditional rare earth permanent magnet components are assembled and formed by gluing. The gluing assembly method has the following defects: 1. When the bonding area of ​​the magnet is small, especially when the Halbach magnetic assembly has no support, its structural stability and weather resistance of the glue are relatively poor, and cannot meet the increasingly high-end use requirements. Although highly weather-resistant glue can be used to improve the weather resistance of the glue, the glue can only reach a maximum bonding strength of 22MPa, and the structural stability still cannot meet the requirements, especially when the magnet bonding area is less than 10mm 2 , and without iron support parts, the life of Halbach magnetic components assembled with glue under high temperature and high humidity conditions of 85°C and 85% relative humidity cannot reach 500 hours, which cannot meet the reliability requirements in high-end applications.

[0003] 2. In the traditional glue bonding process, in order to ensure the bonding strength, a large amount of glue is applied, resulting in a large amount of glue overflow. After the glue solidifies, it takes a lot of manpower to deal with the overflow, and it also causes a lot of glue waste.

[0004] 3. The glue curing time is long, which will affect the assembly speed of rare earth permanent magnet components, and the assembly efficiency is low, which is not suitable for automated mass production.

[0005] Patent CN118248429A discloses a magnetic suction component and its assembly method, a linear motor, a camera, and an electronic device. Although the patent discloses the use of soldering to assemble the Halbach magnetic component, it does not disclose the specific steps of soldering. Summary of the invention

[0006] The object of the present invention is to provide a soldering process for a rare earth permanent magnet assembly. The soldering process is used to assemble magnets, and the assembly speed is fast without glue overflow. The assembled rare earth permanent magnet assembly has extremely high structural stability and high temperature and humidity resistance.

[0007] To achieve the above object, the present invention provides a soldering process for a rare earth permanent magnet assembly, comprising the following steps: S1. Use the visual positioning mechanism to accurately locate the spraying area of ​​the magnet welding surface. The spraying area is located at the center of the magnet welding surface. The area of ​​the spraying area is 40%-54% of the magnet welding surface area. Then use the sprayer to spray solder paste on the spraying area. Every 1mm2 The amount of solder paste used in the spraying area is 0.09-0.11mg; S2. Arrange and place multiple magnets sprayed with solder paste on a magnetic fixture, press all the magnets with a hot pressing head of a hot pressing device, and then use a push rod to push the magnets sideways to press all the magnets together; S3, the hot pressing head of the hot pressing equipment is heated to hot press all the magnets to melt the solder paste; S4. After the solder paste melts, the hot pressing equipment stops heating and introduces compressed air to cool the hot pressing head and the magnet, so that the solder paste solidifies quickly, thereby soldering multiple magnets together to form a rare earth permanent magnet assembly.

[0008] Furthermore, in step S1, if the magnet is a rectangular bar magnet and the aspect ratio of the magnet welding surface is 10:1, the length of the spraying area is 80%-90% of the length of the magnet welding surface, and the width of the spraying area is 50%-60% of the width of the magnet welding surface.

[0009] Further, in step S1, the visual positioning mechanism is a camera, and the camera and the sprayer are both connected to a controller signal. The camera takes a picture of the magnet welding surface and sends the image obtained by the photo to the controller. The controller analyzes and confirms the position of the spraying area, and then controls the sprayer to accurately spray the corresponding amount of solder paste on the spraying area.

[0010] Further, in step S2, two push rods are used to simultaneously squeeze the magnets on both sides to press the magnets together.

[0011] Further, in step S2, if three magnets are used to assemble the Halbach magnetic assembly, the three magnets are placed on the magnetic conductive fixture in the form of a Halbach array, and solder paste is sprayed only on the welding surfaces of the two magnets on both sides.

[0012] Further, in step S3, the hot pressing temperature of the hot pressing head of the hot pressing equipment on the magnet is 160-180° C., and the hot pressing time is 6-12 seconds.

[0013] Further, in step S4, compressed air is introduced to cool the thermal pressing head and the magnet for 2-5 seconds.

[0014] Further, in step S3, a nickel layer is electroplated on the surface of the magnet, and during hot pressing, the solder paste is fully melted and penetrates into the nickel layer to form a strong bond.

[0015] Furthermore, in steps S1-S4, the solder paste is a micron-nano low-temperature solder paste, the raw material components of the solder paste include tin, bismuth, silver and epoxy resin, and the melting point of the solder paste is 139°C.

[0016] Furthermore, after step S4, the soldering strength of the manufactured rare earth permanent magnet assembly reaches 55 MPa, the magnetic property decay is ≤3%, and the service life under high temperature and high humidity conditions of 85°C and 85% relative humidity is 500h.

[0017] After adopting the above scheme, the beneficial effects of the present invention are: 1. The present invention uses solder paste instead of traditional glue to assemble magnets, which can form a high-strength welding layer between magnets with a welding surface less than 10mm², and the welding strength can reach 55MPa; and the service life under high temperature and high humidity conditions of 85°C and 85% relative humidity reaches 500h, with extremely high structural stability and high temperature and high humidity resistance, meeting the reliability requirements in high-end applications.

[0018] 2. The present invention can accurately locate the spraying area of ​​the magnet welding surface and control the spraying amount of the spraying machine through the cooperation of the visual positioning mechanism and the controller. According to the advantage of the solder paste welding strength reaching 55MPa, the appropriate welding position and the smaller amount of solder paste can be controlled, that is, the spraying area is controlled to be located at the center of the magnet welding surface, and the area of ​​the spraying area is 40%-54% of the magnet welding surface area, and every 1mm 2 The amount of solder paste in the spraying area is 0.09-0.11mg, so there will be no solder paste overflow during the welding process. This solves the problem of large amounts of glue overflow caused by applying a large amount of glue in order to ensure the bonding strength in the traditional glue bonding process, saving labor costs and reducing resource waste.

[0019] 3. The hot pressing and cooling curing time of solder paste is extremely short, the assembly efficiency is high, and it is more suitable for automated mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of spraying solder paste of the present invention on the welding surface of a magnet; Figure 2 A schematic diagram of the present invention showing that a plurality of magnets are arranged in the form of a Halbach array on a magnetic conductive fixture; Figure 3 It is a schematic diagram of the hot pressing head of the present invention pressing down the magnet; Figure 4 This is a schematic diagram of the present invention using two push rods to synchronously squeeze the magnets on both sides; Figure 5 It is a process flow chart of the present invention.

[0021] Description of labels: 1. Welding surface; 2. Spraying area; 3. Hot pressing head; 4. Magnetic fixture; 5. Push rod. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1-5 As shown, the present invention provides a soldering process for a rare earth permanent magnet assembly, comprising the following steps: S1. Use a visual positioning mechanism, a controller and a sprayer to spray solder paste on the welding surface 1 of the magnet.

[0024] First, a visual positioning mechanism is used to accurately locate the spraying area 2 of the magnet welding surface 1. The visual positioning mechanism can use a camera or a camera. The present invention preferably uses a camera. The camera and the sprayer are both connected to the controller signal. The camera can take a picture of the magnet welding surface 1. After taking the picture, the acquired image is sent to the controller. The controller can analyze and confirm the position of the spraying area 2, and then control the motion mechanism of the sprayer to move the sprayer to find the position of the spraying area 2, and accurately spray the appropriate amount of solder paste on the spraying area 2. In addition to controlling the motion mechanism of the sprayer, the controller can also control the spraying amount of the sprayer.

[0025] Preferably, the controller has a control system, and the control system has a learning function. The camera sends the captured image to the control system, and the control system can determine the specific position of the spraying area 2 according to the area and shape of the welding surface 1, and can even calculate the area of ​​the spraying area 2 and the amount of solder paste. The area of ​​the spraying area 2 and the amount of solder paste can also be set in advance, and then the controller determines the position of the spraying area 2 and controls the sprayer to spray the corresponding amount of solder paste.

[0026] Furthermore, in order to ensure that the assembled magnetic assembly has sufficient assembly strength and that there will be no solder paste overflow during the subsequent welding process, it is necessary to control the appropriate welding position and a smaller amount of solder paste. As shown in 1, the spraying area 2 should be located at the center of the magnet welding surface 1. It has been verified that when the area of ​​the spraying area 2 is controlled to be 40%-54% of the area of ​​the magnet welding surface 1 and the amount of solder paste per 1mm2 of the spraying area 2 is controlled in the range of 0.09-0.11mg, it can meet the high-end application requirements of 55MPa welding strength and high temperature and high humidity resistance (the service life reaches 500h under high temperature and high humidity conditions of 85℃ and 85% relative humidity).

[0027] Specifically, taking a rectangular bar magnet as an example, if the aspect ratio of the magnet welding surface 1 is 10:1, the length of the spraying area 2 is 80%-90% of the length of the magnet welding surface 1, and the width of the spraying area 2 is 50%-60% of the width of the magnet welding surface 1. For example, if the length of the magnet welding surface 1 is 10mm and the width is 1mm, the length of the spraying area 2 is 8-9mm and the width is 0.5-0.6mm. This setting can ensure that when the spraying area 2 and the amount of solder paste are sufficient, there is enough space between the spraying area 2 and the edge of the magnet to prevent the solder paste from overflowing the magnet during subsequent hot pressing, especially in the width direction of the welding surface 1, which is the height direction of the magnet. Controlling the width of the spraying area 2 to 50%-60% of the width of the magnet welding surface 1 can prevent the solder paste from overflowing upward and contacting the hot pressing head 3, and overflowing downward and contacting the guide fixture 4.

[0028] S2, such as Figure 2-4 As shown, multiple magnets sprayed with solder paste are arranged and placed on a magnetic conductive fixture 4, and then all the magnets are pressed by a hot pressing head 3 of a hot pressing device, and then all the magnets are pressed together by pushing the magnets sideways with a push rod 5. The number of the push rods 5 is preferably two, and the two push rods 5 can squeeze the magnets on both sides simultaneously to ensure that the magnets can be fully squeezed together, so that the assembled magnetic components have higher precision.

[0029] The magnet of the present invention is a rare earth permanent magnet, preferably a neodymium iron boron magnet, and multiple magnets can be placed on the magnetic fixture 4 in any arrangement of rare earth permanent magnet components, such as the arrangement of the Halbach array. The Halbach magnetic component is a type of rare earth permanent magnet component. Figure 2 As shown, taking the assembly of a Halbach magnetic component with three magnets as an example, after spraying solder paste, the three magnets are placed on a magnetic fixture 4 in the form of a Halbach array. In step S1, solder paste can be sprayed only on the welding surfaces 1 of the two magnets on both sides, and the middle magnet is not sprayed with solder paste.

[0030] S3, the hot pressing head 3 of the hot pressing equipment is heated to hot press all the magnets. The hot pressing head 3 of the hot pressing equipment is a heat conducting device. After the hot pressing equipment heats the hot pressing head 3, the hot pressing head 3 transfers the temperature to the magnets, so that the hot pressing head 3 hot presses all the magnets. The hot pressing temperature needs to be higher than the melting point of the solder paste to melt the solder paste, but the hot pressing temperature cannot be too high, which will damage the performance of the magnets. Therefore, a low-temperature solder paste should be selected. The present invention preferably uses a micron-nano low-temperature solder paste. The particle size of the tin alloy particles in the micron-nano low-temperature solder paste is 2-8μm. In order to achieve precise coating on extremely small bonding surfaces, the raw material components of solder paste include tin, bismuth, silver and epoxy resin. Among them, tin is the main component of solder paste and plays the role of welding conductivity. Bismuth is a medium that lowers the melting point. Silver has high conductivity and can improve brittleness. Epoxy resin has the functions of anti-corrosion and improving welding strength and toughness. The melting point of this micron nano low-temperature solder paste is 139°C, and the hot pressing temperature can be controlled within the range of 160-180°C. It will not damage the magnet and can quickly melt the solder paste. The hot pressing time only takes 6-12s.

[0031] Since the surface of the magnet is electroplated with a nickel layer, which is a tin-philic material, the solder paste will fully melt and penetrate into the nickel layer during hot pressing to form a strong bond. After subsequent cooling and solidification, the magnets can be welded together to form a rare earth permanent magnet assembly.

[0032] S4. After the solder paste melts, the hot pressing equipment stops heating, and then cools and solidifies the solder paste. Compressed air can be introduced to cool the hot pressing head 3 and the magnet. It only takes 2-5 seconds of compressed air to completely solidify the solder paste, thereby soldering multiple magnets together to form a rare earth permanent magnet assembly.

[0033] Specifically, the air outlet of the compression fan can be connected to the hot pressing head 3 of the hot pressing equipment through an air pipe, and the compression fan introduces compressed air to the hot pressing head 3. When the hot pressing head 3 is cooled, the cooling temperature is transmitted to the magnet to cool the magnet.

[0034] In addition to using the hot pressing head of the hot pressing equipment for hot melt welding of solder paste, nitrogen protected reflow soldering equipment can also be used for hot melt welding of solder paste. Nitrogen protected reflow soldering is to use hot air flow to act on the solder paste to melt and cool it to achieve the purpose of welding. Compared with hot pressing equipment, it can weld multiple groups of products at a time, but the heating time is longer, the magnetic performance attenuation can reach 5% to 15%, and the temperature resistance of the magnet needs to be improved to meet the process. Improving the temperature resistance of the magnet will lead to an increase in material costs.

[0035] In addition, you can also use laser heating on the magnet surface to perform hot melt welding of solder paste. However, the laser heating efficiency is slightly lower than that of hot pressing. It takes 15 to 20 seconds to completely melt the solder paste, and the cost of laser heating equipment is about 10 times higher than that of hot pressing equipment. Therefore, hot pressing process is the best choice for soldering magnets.

[0036] The following is further described by examples and comparative examples: Embodiment 1: The three magnets are assembled into a Halbach magnetic assembly using the soldering process described above, and the solder paste is a micron-nano low-temperature solder paste.

[0037] Comparative Example 1: The three magnets are assembled into a Halbach magnetic assembly using a glue bonding process. For details, please refer to the assembly method disclosed in patent CN118248429A.

[0038] The performance of the Halbach magnetic assembly assembled from Example 1 and Comparative Example 1 was tested, and the test results are shown in the following table:

[0039] As can be seen from the above table, the assembly strength of the Halbach magnetic assembly assembled in Example 1 reaches 55MPa, and the lifespan under 85°C and 85% relative humidity is 500h, which are much higher than those in Comparative Example 1, meeting the needs of high-end applications. Moreover, Example 1 uses micron-nano low-temperature solder paste for welding. Although the melting point of the micron-nano low-temperature solder paste is higher than the curing temperature of the glue in the traditional assembly process, the solder paste can start to cool and solidify as soon as it reaches a completely molten state. Therefore, the duration of the magnet at high temperature is extremely short, and the damage to the magnet is not great. The magnetic performance attenuation of the Halbach magnetic assembly can be controlled to be less than 3%, which is similar to Comparative Example 1. Therefore, the soldering process of the present invention can be used to replace the traditional glue bonding process to assemble the magnet to meet the needs of high-end applications.

[0040] In addition, the welding time of Example 1 is only 8-17s, including 6-12s of hot pressing and 2-5s of cooling, while Comparative Example 1 requires 10-30mm of glue curing time. Therefore, the assembly speed of the soldering process of the present invention is much faster than that of the glue bonding process, the assembly efficiency is high, and it is more suitable for automated mass production.

[0041] The above description is only a preferred embodiment of the present invention and is not a limitation on the design of this case. Any equivalent changes made based on the design key of this case shall fall within the protection scope of this case.

Claims

1. A soldering process for rare earth permanent magnet components, characterized in that: The following steps are involved: S1. Use the visual positioning mechanism to accurately locate the spraying area of ​​the magnet welding surface. The spraying area is located at the center of the magnet welding surface. The area of ​​the spraying area is 40%-54% of the magnet welding surface area. Then use the sprayer to spray solder paste on the spraying area. Every 1mm 2 The amount of solder paste used in the spraying area is 0.09-0.11mg; S2. Arrange and place multiple magnets sprayed with solder paste on a magnetic fixture, press all the magnets with a hot pressing head of a hot pressing device, and then use a push rod to push the magnets sideways to press all the magnets together; S3, the hot pressing head of the hot pressing equipment is heated to hot press all the magnets to melt the solder paste; S4. After the solder paste melts, the hot pressing equipment stops heating and introduces compressed air to cool the hot pressing head and the magnet, so that the solder paste solidifies quickly, thereby soldering multiple magnets together to form a rare earth permanent magnet assembly.

2. The soldering process of a rare earth permanent magnet assembly as claimed in claim 1, characterized in that: In step S1, if the magnet is a rectangular bar magnet and the aspect ratio of the magnet welding surface is 10:1, the length of the spraying area is 80%-90% of the length of the magnet welding surface, and the width of the spraying area is 50%-60% of the width of the magnet welding surface.

3. The soldering process of a rare earth permanent magnet assembly as claimed in claim 1, characterized in that: In step S1, the visual positioning mechanism is a camera, and the camera and the sprayer are both connected to a controller signal. The camera takes a picture of the magnet welding surface and sends the image obtained by the photo to the controller. The controller analyzes and confirms the position of the spraying area, and then controls the sprayer to accurately spray the corresponding amount of solder paste on the spraying area.

4. The soldering process of a rare earth permanent magnet assembly as claimed in claim 1, characterized in that: In step S2, two push rods are used to simultaneously squeeze the magnets on both sides to press the magnets together.

5. A soldering process for a rare earth permanent magnet assembly as claimed in claim 1 or 4, characterized in that: In step S2, if three magnets are used to assemble the Halbach magnetic assembly, the three magnets are placed on a magnetic conductive fixture in the form of a Halbach array, and solder paste is sprayed only on the welding surfaces of the two magnets on both sides.

6. The soldering process of a rare earth permanent magnet assembly as claimed in claim 1, characterized in that: In step S3, the hot pressing temperature of the hot pressing head of the hot pressing equipment on the magnet is 160-180° C., and the hot pressing time is 6-12 seconds.

7. A soldering process for a rare earth permanent magnet assembly as claimed in claim 1 or 6, characterized in that: In step S4, compressed air is introduced to cool the thermal compression head and the magnet for 2-5 seconds.

8. A soldering process for a rare earth permanent magnet assembly as claimed in claim 1 or 6, characterized in that: In step S3, a nickel layer is electroplated on the surface of the magnet. During hot pressing, the solder paste is fully melted and penetrates into the nickel layer to form a strong bond.

9. A soldering process for a rare earth permanent magnet assembly as claimed in claim 1 or 6, characterized in that: In steps S1-S4, the solder paste is a micron-nano low-temperature solder paste, the raw material components of the solder paste include tin, bismuth, silver and epoxy resin, and the melting point of the solder paste is 139°C.

10. The soldering process of a rare earth permanent magnet assembly according to claim 1, characterized in that: After step S4, the soldering strength of the manufactured rare earth permanent magnet assembly reaches 55 MPa, the magnetic property decay is ≤3%, and the service life is 500 h under high temperature and high humidity conditions of 85° C. and 85% relative humidity.

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