An ultrasonic unit and welding device for small pressure welding

Abstract

The application belongs to the technical field of IGBT welding and specifically relates to an ultrasonic unit for small-pressure welding and a welding device, wherein the ultrasonic unit comprises a base, a horizontal part and a vertical part; a welding assembly is slidably connected to the vertical part of the base, the welding assembly comprises an ultrasonic triple group configured to weld a workpiece; and a driving assembly is arranged between the horizontal part of the base and the ultrasonic triple group, the driving assembly comprises a driving part and a magnetic spring, the magnetic spring is arranged in parallel with the driving part, the driving part is configured to provide welding pressure for the ultrasonic triple group, and the magnetic spring is configured to balance the gravity of the welding assembly; the application can realize small-pressure welding of the workpiece and avoid direct damage to the surface of the workpiece due to excessive gravity of the welding assembly.

Description

Technical Field

[0001] This invention belongs to the field of IGBT welding technology, specifically relating to an ultrasonic unit and welding device for low-pressure welding. Background Technology

[0002] A power module is a semiconductor package used in power electronic circuits. For example, it may encapsulate an insulated-gate bipolar transistor (IGBT) chip or a metal-oxide-semiconductor field-effect transistor (MOSFET) chip. These power semiconductor chips offer a range of voltage and current ratings to suit various applications or industries.

[0003] Ultrasonic welding is a crucial step in IGBT module manufacturing, where the terminals of IGBT chips are welded onto a copper-clad ceramic substrate. In applying ultrasonic welding to IGBT modules, the inventors have identified at least the following technical problems:

[0004] In existing IGBT modules, the terminal welding pressure is mostly above 300N. However, due to the presence of a ceramic substrate within the IGBT module, welding pressures of less than 100N or even as low as 30N are required in some applications. Excessive pressure can damage the ceramic substrate, resulting in damage to the welded product. Furthermore, the self-weight of the welding assembly exceeds 80N, surpassing the maximum welding pressure required for welding applications and failing to meet the normal needs of low-pressure welding scenarios.

[0005] Therefore, it is necessary to improve upon the shortcomings of existing technologies in order to overcome their deficiencies in practical applications. Summary of the Invention

[0006] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide an ultrasonic unit and welding apparatus for low-pressure welding that meets one or more of the aforementioned requirements.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] This invention provides an ultrasonic unit for low-pressure welding, comprising:

[0009] The base includes a horizontal section and a vertical section;

[0010] A welding assembly, slidably connected to the vertical portion of the base, the welding assembly including an ultrasonic triple unit configured to weld a workpiece; and

[0011] A drive assembly is disposed between the horizontal portion of the base and the ultrasonic triple unit. The drive assembly includes a drive unit and a magnetic spring. The magnetic spring is arranged parallel to the drive unit. The drive unit is configured to provide welding pressure to the ultrasonic triple unit, and the magnetic spring is configured to balance the weight of the welding assembly.

[0012] As a preferred embodiment, the ultrasonic triplet includes a transducer, an amplitude modulator, and an ultrasonic welding head, wherein the transducer is connected to the amplitude modulator, and the amplitude modulator is connected to the ultrasonic welding head.

[0013] As a preferred embodiment, the welding assembly further includes a detection element, the two ends of which are respectively connected to the horizontal portion of the base and the driving portion.

[0014] As a preferred embodiment, the ultrasonic welding head is provided with a fixing block, the fixing block having a cavity, and the driving unit is installed inside the cavity.

[0015] As a preferred embodiment, the driving unit includes a spring, with its two ends connected to the detection element and the ultrasonic welding head, respectively.

[0016] The welding assembly also includes a first clamp, a second clamp, and a transition block. The transition block is connected to the ultrasonic triple unit. The first clamp and the second clamp are respectively connected to the transition block. The first clamp is connected to the amplitude modulator, and the second clamp is connected to the magnetic spring.

[0017] As a preferred embodiment, the magnetic spring is installed on the horizontal part of the base, and the magnetic spring is connected to the ultrasonic triple unit through the second clamp.

[0018] As a preferred embodiment, the magnetic spring includes a stator and a mover, the mover moves relative to the stator, and the direction of the mover's movement is parallel to the direction of the force applied by the driving part.

[0019] As a preferred embodiment, the welding assembly further includes a guide assembly, which includes a slider and a slide rail. The slider is connected to the ultrasonic triple unit, and the slide rail is located in the vertical part of the base. The slider and the slide rail are slidably connected.

[0020] The present invention also provides an ultrasonic welding apparatus, including a frame, a Z-axis drive mechanism, and an ultrasonic unit as described in any of the above embodiments. The Z-axis drive mechanism is mounted on the frame, connected to the base, and used to drive the base to move along the Z-axis.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] The present invention provides an ultrasonic unit for low-pressure welding. During the welding of IGBT modules, the welding pressure is provided by a spring and the weight of the welding assembly is compensated by a magnetic spring, so as to realize low-pressure welding of IGBT modules and avoid the product surface being directly damaged by excessive weight of the welding assembly.

[0023] The present invention provides an ultrasonic unit for low-pressure welding, which can accurately control the welding pressure and ensure the consistency of the welding by detecting pressure changes in real time during welding through a pressure sensor. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the ultrasonic unit according to an embodiment of the present invention;

[0026] Figure 2 This is a front view of the ultrasonic unit according to an embodiment of the present invention;

[0027] Figure 3 This is a side view of the ultrasonic unit according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the magnetic spring according to an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the welding apparatus according to an embodiment of the present invention;

[0030] In the diagram: 1. Base, 11. Horizontal section, 12. Vertical section, 13. Grating ruler, 2. Welding assembly, 21. Ultrasonic triple unit, 211. Ultrasonic welding head, 212. Amplitude modulator, 213. Transducer, 22. Detector, 23. Fixing block, 24. First clamp, 25. Second clamp, 26. Transition block, 3. Drive assembly, 31. Drive unit, 32. Magnetic spring, 321. Stator, 322. Mover, 4. Guide assembly, 41. Slider, 42. Slide rail, 5. Frame, 6. Z-axis drive mechanism. Detailed Implementation

[0031] To more clearly illustrate the embodiments of the present invention, specific implementation methods will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0032] In the description of the embodiments of the present invention, the terms "upper" and "lower," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second," etc., are only used for distinction in description and have no special meaning.

[0033] Ultrasonic welding is a crucial step in IGBT module manufacturing, where the terminals of IGBT chips are welded onto a copper-clad ceramic substrate. Currently, the welding pressure for terminals in most IGBT modules exceeds 300N. However, due to the presence of a ceramic substrate within the IGBT module, welding pressures of less than 100N or even as low as 30N are used in some applications. Since the self-weight of the welding components can reach over 80N, exceeding the maximum welding pressure required for IGBT welding, excessive pressure can easily damage the ceramic substrate within the IGBT module, resulting in damage to the welded product.

[0034] To address the aforementioned technical problems, some embodiments of this application are described below. Figures 1 to 4 As shown, an ultrasonic unit for low-pressure welding is provided, including a base 1, a welding assembly 2 and a drive assembly 3. The base 1 includes a horizontal part 11 and a vertical part 12. The horizontal part 11 is used to connect the drive assembly 3, and the vertical part 12 is used to move the welding assembly 2 up and down.

[0035] The welding assembly 2 includes an ultrasonic triplet 21 configured to weld a workpiece. The ultrasonic triplet 21 includes a transducer 213, an amplitude modulator 212, and an ultrasonic welding head 211. The transducer 213 is connected to the amplitude modulator 212, and the amplitude modulator 212 is connected to the ultrasonic welding head 211.

[0036] Specifically, high-frequency electrical energy is converted into mechanical vibration by transducer 213, and amplitude modulator 212 is used to adjust the amplitude of mechanical vibration, mainly to amplify the vibration. The final vibration is concentrated on ultrasonic welding head 211, and ultrasonic welding head 211 drives the load to complete the welding work under high-frequency vibration.

[0037] In order to control the welding pressure of the ultrasonic welding head 211 pressing down on the workpiece, a power source is required through the drive assembly 3. Specifically, the drive assembly 3 is located between the horizontal part 11 of the base 1 and the ultrasonic triple unit 21. The drive assembly 3 includes a drive part 31 and a magnetic spring 32. The magnetic spring 32 is arranged parallel to the drive part 31. The drive part 31 is configured to provide welding pressure to the ultrasonic triple unit 21. The magnetic spring 32 is configured to balance the weight of the welding assembly 2 to avoid the IGBT module substrate being crushed by the weight of the welding assembly during welding, thus ensuring that the workpiece is welded with low pressure.

[0038] Furthermore, the drive unit 31 is configured as a spring 311. Since the IGBT module requires low-pressure welding, the welding pressure is provided by the spring. On the one hand, the ultrasonic unit has a compact structure, and the spring structure is easy to disassemble and saves space. On the other hand, the welding pressure provided by the spring can meet the needs of low-pressure welding scenarios.

[0039] According to some embodiments of this application, the welding assembly 2 further includes a detection element 22. The two ends of the detection element 22 are respectively connected to the horizontal part 11 of the base 1 and the spring 311. The detection element 22 is a pressure sensor. The upper end of the pressure sensor is fixedly connected to the horizontal part 11 of the base 1, and the lower end of the pressure sensor is fixedly connected to the spring 311. The pressure sensor detects the pressure change of the ultrasonic welding head 211 when welding the workpiece in real time, so as to accurately control the welding pressure.

[0040] Furthermore, the lower end of the spring 311 is connected to the ultrasonic welding head 211. The spring 311 can drive the ultrasonic welding head 211 to move downward to weld the workpiece. At this time, the pressure sensor obtains the welding pressure between the ultrasonic welding head 211 and the workpiece so as to adjust the pressure value during welding according to the actual situation to ensure a reliable weld.

[0041] Furthermore, a fixing block 23 is provided on the ultrasonic welding head 211, and the fixing block 23 is fixedly connected to the ultrasonic welding head 211. The fixing block 23 has a cavity inside, and a spring 311 is installed in the cavity to ensure that the spring 311 can freely expand and contract within the cavity. When the ultrasonic welding head 211 contacts the surface of the workpiece, the spring 311 is compressed so that the spring 311 provides welding pressure.

[0042] Generally speaking, the depth of the cavity of the fixing block 23 is less than the length of the spring 311 in the static state. During installation, the spring 311 is housed in the cavity to prevent the spring 311 from extending out of the outside of the fixing block 23 and affecting the welding pressure provided by the spring 311, thus preventing the spring 311 from shifting and failing, making the overall structure of the welding assembly more compact and reliable.

[0043] According to some embodiments of this application, the welding assembly 2 further includes a first clamp 24, a second clamp 25, and a transition block 26. The transition block 26 is connected to the fixed block 23. The first clamp 24 and the second clamp 25 are respectively connected to the transition block 26. The first clamp 24 is connected to the amplitude modulator 212, and the second clamp 25 is connected to the magnetic spring 32.

[0044] Specifically, the first clamp 24 can not only ensure the axial force balance of the ultrasonic triple unit 21, but also be connected to the ultrasonic triple unit 21 as a whole through the transition block 26, the second clamp 25 and the fixing block 23. The second clamp 25 can cooperate with the magnetic spring so that the whole can move up and down synchronously.

[0045] In a specific embodiment, the first clamp 24, the second clamp 25, and the transition block 26 can be connected as a single unit, which can improve the structural strength of the overall component and ensure the welding quality.

[0046] In a specific embodiment, the first clamp 24, the second clamp 25, and the transition block 26 can be connected in a separate manner, which facilitates the installation, disassembly, or replacement of each component separately, thereby improving efficiency. In specific applications, the configuration can be tailored to actual needs.

[0047] In order to provide welding pressure through spring 311, it is necessary to ensure that the weight of welding assembly 2 does not affect the welding pressure. To this end, a magnetic spring 32 is set to balance the weight of welding assembly 2, so that the welding pressure when ultrasonic welding head 211 welds workpiece is provided only through spring 311 and is not affected by the overall weight of welding assembly 2.

[0048] Due to the limited space within the base of the welding assembly 2, the installation structure is compact. The magnetic spring 32 must both compensate for the gravity of the welding assembly 2 and ensure the stability of the welding assembly 2's up-and-down movement.

[0049] Specifically, the magnetic spring 32 includes a stator 321 and a mover 322. The mover 322 moves relative to the stator 321, and the direction of movement of the mover 322 is parallel to the direction of force applied by the spring 311. In a specific embodiment, the magnetic spring 32 can be fixed at one end, fixing one end of the stator 321. The stator 321 has a hollow internal structure. The mover 322 is telescopically fitted to the stator 321, and the magnetic force between them causes the mover 322 to move up and down along the stator 321, thereby driving the second clamp 25 to move up and down. The single-end fixing method of the magnetic spring 32 is suitable for short-stroke welding methods.

[0050] In some specific embodiments, such as Figure 4 As shown, the magnetic spring 32 can also be fixed at both ends, fixing both ends of the stator 321. The mover 322 is connected to the second clamp 25 and sleeved outside the stator 321. The magnetic force between the mover 322 and the stator 321 causes the mover 322 to move up and down relative to the stator 321, thereby driving the second clamp 25 to move up and down. The double-end fixing method of the magnetic spring 32 can ensure long-stroke welding. In practical applications, it can be set according to requirements to meet application scenarios with different welding stroke lengths.

[0051] Furthermore, a grating ruler 13 is provided on the inner side of the base 1. The stroke of the welding component 2 can be accurately measured through the grating ruler 13 to ensure that the welding is precise and controllable.

[0052] The magnetic spring 32 can eliminate the impact force of the gravity of the welding assembly on the substrate in the IGBT module, ensuring the stability of the welding operation of the welding assembly and the consistency of the welding of the workpiece.

[0053] To ensure the overall vertical movement of the welding assembly, the welding assembly 2 also includes a guide assembly 4. The guide assembly 2 is located between the fixed block 23 and the vertical part 12 of the base 1. The guide assembly includes a slider 41 and a slide rail 42. The slider 41 is connected to the fixed block 23, and the slide rail 42 is located in the vertical part 11 of the base 1. The slider 41 and the slide rail 42 are slidably connected.

[0054] To describe in detail the force changes of the ultrasonic unit during the welding process, its working principle is explained below.

[0055] When the welding assembly 2 moves downwards to the welding position, the ultrasonic welding head 211 comes into contact with the workpiece, the spring 311 is compressed, and the pressure change is detected by the pressure sensor. The gravity of the welding assembly 2 is compensated and offset by the magnetic spring 32, and the welding pressure of the welding assembly 2 is provided by the spring 311.

[0056] When the ultrasonic unit welds the workpiece, it includes three working processes. In the first working process, the welding assembly moves downward as a whole from the initial position and comes into contact with the surface of the workpiece. In the first working process, the magnetic spring counteracts the gravity of the welding assembly. Since the gravity of the welding assembly is constant, the compensating force of the magnetic spring during the movement process also remains constant.

[0057] During the second working process, the welding assembly continues to press down from the contact position to the welding position, and the ultrasonic welding head presses down on the workpiece to achieve the required welding pressure. During this process, the welding assembly moves upward through the guide assembly so that the spring is compressed so that the spring can provide welding pressure.

[0058] In the third working process, the ultrasonic waves are activated, converting high-frequency electrical energy into mechanical vibration through a transducer. This high-frequency vibration is then transmitted to the ultrasonic welding head via an amplitude modulator, where the ultrasonic welding head welds the workpiece under high-frequency vibration. During this process, the elastic force released by the spring applies welding pressure to the workpiece, maintaining a relatively constant welding pressure.

[0059] The following analysis examines the welding pressure during the welding process, where F represents the welding pressure on the workpiece, F1 represents the compensating force of the magnetic spring, G represents the weight of the welding assembly, F2 represents the force generated by the spring compression deformation, F3 represents the displayed value of the pressure sensor, and f represents the frictional force between the welding assembly and the guide rail.

[0060] (1) When the compensating force of the magnetic spring is equal to the weight of the welding assembly, i.e., F1 = G, the welding pressure at this time is F = F2 + f; where F2 = F3, i.e., F = F3 + f.

[0061] (2) When the compensation force of the magnetic spring is greater than the self-weight of the welding component, that is, F1 > G, the welding pressure F at this time is F = F2 + f, where F2 = F3 - (F1 - G), that is, F = F3 + G - F1 + f.

[0062] (3) When the compensation force of the magnetic spring is less than the self-weight of the welding component, that is, F1 < G, the welding pressure F at this time is F = F2 + f, where F2 = F3 - (G - F1), that is, F = F3 + F1 - G + f.

[0063] Through the ultrasonic welding unit of the present application, when performing small-pressure welding on power modules such as IGBTs, not only can the welding quality of the welded workpieces be guaranteed, but also the damage to the power module by the ultrasonic welding head during the welding process can be reduced.

[0064] In some specific embodiments, the driving part 31 can also be set as a cylinder or a servo motor, which is rigidly connected to the welding component through the cylinder or the servo motor to replace the spring 311. By providing the welding pressure through the cylinder or the servo motor, the error caused by the spring deformation can be avoided, which is beneficial to improving the welding accuracy.

[0065] According to some embodiments of the present application, as Figure 5 shown, there is also provided an ultrasonic welding device, including a frame, a Z-direction driving mechanism, and the ultrasonic unit as described above. The Z-direction driving mechanism is installed on the frame, and the Z-direction driving mechanism is connected to the base and is used to drive the base to move along the Z direction.

[0066] Specifically, the Z-direction driving mechanism is installed above the frame. The Z-direction driving mechanism is传动连接 with the guide block 71. The guide rail 72 is arranged along the up and down direction of the frame. The guide block 71 is slidably配合 with the guide rail 72. The base of the ultrasonic unit is connected to the guide block 71. By driving the guide block 71 to move up and down along the guide rail 72 through the Z-direction driving mechanism, the ultrasonic unit is further联动 to move up and down.

[0067] The specific process of ultrasonic welding of IGBT is as follows:

[0068] First, drive the ultrasonic unit to move to make the ultrasonic welding head contact the workpiece through the Z-direction driving mechanism; then continue to press down through the ultrasonic unit. At this time, the welding component will move upward along the guiding component to compress the spring to reach the required welding pressure; finally, start the transducer to provide mechanical vibration to the ultrasonic welding head, so that the ultrasonic welding head performs ultrasonic welding on the workpiece to be welded, and drive the welding component to continue to press down through the spring to maintain the required welding pressure. The ultrasonic welding device of the present application can realize small-pressure welding of workpieces and avoid directly crushing the surface of the workpiece due to the excessive gravity of the welding component.

[0069] It should be noted that the "传动连接" in the original text may be a misspelling. It is guessed that it should be "传动连接", which is translated as "传动连接" in the above translation. If this is not the correct expression, please provide the correct information for a more accurate translation.The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. An ultrasonic unit for small pressure welding, characterized in that, The application relates to a welding assembly. The welding assembly comprises a base, a welding assembly and a driving assembly. The base comprises a horizontal part and a vertical part. The welding assembly is slidably connected to the vertical part of the base and comprises an ultrasonic triple unit configured to weld a workpiece. The driving assembly is arranged between the horizontal part of the base and the ultrasonic triple unit and comprises a driving part and a magnetic spring. The magnetic spring is arranged in parallel with the driving part.

2. An ultrasonic unit for small pressure welding according to claim 1, characterized in that The driving part is configured to provide welding pressure to the ultrasonic triple unit.

3. An ultrasonic unit for small pressure welding according to claim 2, characterized in that The magnetic spring is configured to balance the gravity of the welding assembly.

4. An ultrasonic unit for small pressure welding according to claim 3, characterized in that The magnetic spring comprises a stator and a rotor.

5. An ultrasonic unit for small pressure welding according to claim 4, characterized in that The stator is fixed to the horizontal part of the base.

6. An ultrasonic unit for small pressure welding according to claim 2, characterized in that The rotor is fixed to the ultrasonic triple unit.

7. An ultrasonic unit for small pressure welding according to claim 6, characterized in that The rotor moves in parallel with the force direction of the driving part.

8. An ultrasonic unit for small pressure welding according to claim 1, characterized in that The elastic force of the magnetic spring is constant during the welding stroke.

9. An ultrasonic welding device characterized by comprising: The size of the elastic force is equal to the gravity of the welding assembly. The ultrasonic triple unit comprises a transducer, an amplitude modulator and an ultrasonic welding head. The transducer is connected to the amplitude modulator. The amplitude modulator is connected to the ultrasonic welding head. The welding assembly further comprises a detection member. The two ends of the detection member are connected to the horizontal part of the base and the driving part respectively. The ultrasonic welding head is provided with a fixing block. The fixing block has a cavity. The driving part is installed in the cavity. The driving part comprises a spring. The two ends of the spring are connected to the detection member and the ultrasonic welding head respectively. The welding assembly further comprises a first clamp, a second clamp and a transition block. The transition block is connected to the ultrasonic triple unit. The first clamp and the second clamp are connected to the transition block respectively. The first clamp is connected to the amplitude modulator. The second clamp is connected to the magnetic spring. The magnetic spring is installed on the horizontal part of the base. The magnetic spring is connected to the ultrasonic triple unit through the second clamp. The welding assembly further comprises a guide assembly. The guide assembly comprises a sliding block and a sliding rail. The sliding block is connected to the ultrasonic triple unit. The sliding rail is arranged on the vertical part of the base. The sliding block is slidably connected to the sliding rail. The application relates to a welding assembly. The welding assembly comprises a base, a welding assembly and a driving assembly. The base comprises a horizontal part and a vertical part. The welding assembly is slidably connected to the vertical part of the base and comprises an ultrasonic triple unit configured to weld a workpiece. The driving assembly is arranged between the horizontal part of the base and the ultrasonic triple unit and comprises a driving part and a magnetic spring. The magnetic spring is arranged in parallel with the driving part. The driving part is configured to provide welding pressure to the ultrasonic triple unit. The magnetic spring is configured to balance the gravity of the welding assembly. The magnetic spring comprises a stator and a rotor. The stator is fixed to the horizontal part of the base. The rotor is fixed to the ultrasonic triple unit. The rotor moves in parallel with the force direction of the driving part. The elastic force of the magnetic spring is constant during the welding stroke. The size of the elastic force is equal to the gravity of the welding assembly. The ultrasonic triple unit comprises a transducer, an amplitude modulator and an ultrasonic welding head. The transducer is connected to the amplitude modulator. The amplitude modulator is connected to the ultrasonic welding head. The welding assembly further comprises a detection member. The two ends of the detection member are connected to the horizontal part of the base and the driving part respectively. The ultrasonic welding head is provided with a fixing block. The fixing block has a cavity. The driving part is installed in the cavity. The driving part comprises a spring. The two ends of the spring are connected to the detection member and the ultrasonic welding head respectively. The welding assembly further comprises a first clamp, a second clamp and a transition block. The transition block is connected to the ultrasonic triple unit. The first clamp and the second clamp are connected to the transition block respectively. The first clamp is connected to the amplitude modulator. The second clamp is connected to the magnetic spring. The magnetic spring is installed on the horizontal part of the base. The magnetic spring is connected to the ultrasonic triple unit through the second clamp. The welding assembly further comprises a guide assembly. The guide assembly comprises a sliding block and a sliding rail. The sliding block is connected to the ultrasonic triple unit. The sliding rail is arranged on the vertical part of the base. The sliding block is slidably connected to the sliding rail.

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