Ultrasonic unit for small-pressure welding and welding device

Abstract

The invention belongs to the technical field of IGBT welding, and particularly relates to an ultrasonic unit for small-pressure welding and a welding device.The ultrasonic unit comprises a base which comprises a horizontal part and a vertical part; the welding assembly is connected to the vertical part of the base in a sliding mode, the welding assembly comprises an ultrasonic triple set, and the ultrasonic triple set is configured to weld a workpiece; the driving assembly is arranged between the horizontal part of the base and the ultrasonic triple set, the driving assembly comprises a driving part and a magnetic spring, the magnetic spring and the driving part are arranged in parallel, the driving part is configured to provide welding pressure for the ultrasonic triple set, and the magnetic spring is configured to provide welding pressure for the ultrasonic triple set. The magnetic spring is configured to balance the gravity of the welding assembly; small-pressure welding of workpieces can be achieved, and the situation that the surfaces of the workpieces are directly crushed due to too large gravity of a welding assembly is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of IGBT welding, and in particular relates to an ultrasonic unit and a welding device for low-pressure welding. Background Art

[0002] A power module is a semiconductor package used in power electronic circuits, such as a module that encapsulates an insulated gate bipolar transistor (IGBT) chip or a metal oxide semiconductor field effect transistor (MOSFET) chip. The above power semiconductor chips have a range of voltage and current levels to suit different occasions or industry applications.

[0003] Welding the terminals of the IGBT chip to the copper-clad ceramic substrate by ultrasonic welding technology is an important process in the manufacturing process of the IGBT module. In the application of ultrasonic welding of the IGBT module, the inventors found that there are at least the following technical problems:

[0004] The terminal welding pressure in existing IGBT modules is mostly concentrated above 300N. Due to the presence of ceramic substrates in IGBT modules, the welding pressure is less than 100N or even only 30N in some application scenarios. Excessive pressure will cause the ceramic substrate in the IGBT module to be crushed and damage the welded product. Since the dead weight of the welded assembly reaches more than 80N, it exceeds the maximum welding pressure required in welding applications and cannot meet the normal needs of low-pressure welding scenarios.

[0005] Based on this, it is necessary to improve the defects in the prior art to overcome the shortcomings in practical applications. Summary of the invention

[0006] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide an ultrasonic unit and welding device for low-pressure welding that meet one or more of the above-mentioned needs.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

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

[0009] A base, comprising a horizontal portion and a vertical portion;

[0010] a welding assembly slidably connected to the vertical portion of the base, the welding assembly comprising an ultrasonic triplet group, the ultrasonic triplet group being configured to weld the workpiece; and

[0011] A driving assembly is arranged between the horizontal portion of the base and the ultrasonic triplet group, the driving assembly includes a driving portion and a magnetic spring, the magnetic spring is arranged parallel to the driving portion, the driving portion is configured to provide welding pressure to the ultrasonic triplet group, and the magnetic spring is configured to balance the gravity of the welding assembly.

[0012] As a preferred solution, the ultrasonic triple group includes a transducer, an amplitude modulator and an ultrasonic horn, the transducer is connected to the amplitude modulator, and the amplitude modulator is connected to the ultrasonic horn.

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

[0014] As a preferred solution, a fixing block is provided on the ultrasonic horn, and the fixing block has a cavity, in which the driving part is installed.

[0015] As a preferred solution, the driving part includes a spring, and two ends of the spring are respectively connected to the detection member and the ultrasonic horn.

[0016] The welding assembly also includes a first clamp, a second clamp and a transition block, the transition block is connected to the ultrasonic triplet, 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 solution, the magnetic spring is installed on the horizontal part of the base, and the magnetic spring is connected to the ultrasonic triple group through the second clamp.

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

[0019] As a preferred solution, the welding assembly also includes a guide assembly, which includes a slider and a slide rail, the slider is connected to the ultrasonic triplet, the slide rail is arranged on the vertical part of the base, and the slider is slidably connected to the slide rail.

[0020] The present invention also provides an ultrasonic welding device, comprising a frame, a Z-direction driving mechanism and an ultrasonic unit as described in any of the above schemes, wherein the Z-direction driving mechanism is installed on the frame, connected to the base, and used to drive the base to move along the Z direction.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides an ultrasonic unit for low-pressure welding. When welding an IGBT module, welding pressure is provided by a spring, and the gravity of the welding assembly is compensated by a magnetic spring, so as to achieve low-pressure welding of the IGBT module and avoid direct damage to the product surface due to excessive gravity of the welding assembly.

[0023] The present invention provides an ultrasonic unit for low-pressure welding, which detects pressure changes during welding in real time through a pressure sensor, and can accurately control the welding pressure to ensure welding consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

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

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

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

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

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

[0030] In the figure: 1 base, 11 horizontal part, 12 vertical part, 13 grating ruler, 2 welding assembly, 21 ultrasonic triple group, 211 ultrasonic welding head, 212 amplitude modulator, 213 transducer, 22 detection part, 23 fixed block, 24 first clamp, 25 second clamp, 26 transition block, 3 driving assembly, 31 driving part, 32 magnetic spring, 321 stator, 322 mover, 4 guide assembly, 41 slider, 42 slide rail, 5 frame, 6 Z-direction driving mechanism. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the embodiments of the present invention, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings and other implementation methods can be obtained based on these accompanying drawings without creative work.

[0032] In the description of the embodiments of the present invention, the terms "upper", "lower", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish in the description and have no special meaning.

[0033] Welding the terminals of the IGBT chip to the copper-clad ceramic substrate through ultrasonic welding technology is an important process in the manufacturing process of the IGBT module. The terminal welding pressure in the existing IGBT module is mostly concentrated above 300N. Due to the presence of a ceramic substrate in the IGBT module, the welding pressure is less than 100N or even only 30N in some application scenarios. Since the dead weight of the welded assembly reaches more than 80N, even exceeding the maximum welding pressure required for IGBT welding, excessive pressure can easily cause the ceramic substrate in the IGBT module to be crushed and damage the welded product.

[0034] In order to solve the above technical problems, according to some embodiments of the present application, please refer to 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 driving assembly 3. The base 1 includes a horizontal portion 11 and a vertical portion 12. The horizontal portion 11 is used to connect the driving assembly 3, and the vertical portion 12 is used to move the welding assembly 2 up and down.

[0035] The welding assembly 2 includes an ultrasonic triple group 21, which is configured to weld the workpiece. The ultrasonic triple group 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, the high-frequency electrical energy is converted into mechanical vibration through the transducer 213, and the amplitude modulator 212 is used to adjust the amplitude of the mechanical vibration, mainly for amplifying the vibration. The final vibration is concentrated on the ultrasonic welding head 211, and the ultrasonic welding head 211 drives the load to complete the welding work under the high-frequency vibration.

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

[0038] Furthermore, the driving part 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, since the ultrasonic unit has a compact structure, the spring structure is easy to disassemble and assemble and can save space. On the other hand, the welding pressure is provided by the spring, which can meet the scenario requirements of low-pressure welding.

[0039] According to some embodiments of the present application, the welding assembly 2 also includes a detection piece 22, the two ends of which are respectively connected to the horizontal part 11 of the base 1 and the spring 311. The detection piece 22 adopts 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 is used to detect the pressure changes 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 horn 211, and the spring 311 can drive the ultrasonic horn 211 to move downward to achieve welding of the workpiece. At this time, the pressure sensor obtains the welding pressure between the ultrasonic horn 211 and the workpiece so as to adjust the pressure value during welding according to the actual situation to ensure reliable welding.

[0041] Furthermore, a fixing block 23 is provided on the ultrasonic horn 211, and the fixing block 23 is fixedly connected to the ultrasonic horn 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 in the cavity. When the ultrasonic horn 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 smaller than the length of the spring 311 in the static state. During installation, the spring 311 is accommodated in the cavity to prevent the spring 311 from extending out of the fixing block 23 and affecting the spring 311 in providing welding pressure, thereby preventing the spring 311 from shifting and failing, thereby making the overall structure of the welding assembly more compact and reliable.

[0043] According to some embodiments of the present application, the welding assembly 2 also 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 that the ultrasonic triple group 21 is subjected to balanced force along its axial direction, but can also be connected to the ultrasonic triple group 21 through the transition block 26, the second clamp 25 and the fixed block 23. The second clamp 25 can cooperate with the magnetic spring to enable the whole to move synchronously up and down.

[0045] In a specific embodiment, the first clamp 24, the second clamp 25 and the transition block 26 can be connected in an integrated manner, which can improve the structural strength of the entire component and ensure the welding quality effect.

[0046] In a specific embodiment, the first clamp 24, the second clamp 25 and the transition block 26 can be connected in a split manner, which is convenient for installing, disassembling or replacing each component separately, thereby improving the use efficiency. In a specific application, it can be set according to actual needs.

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

[0048] Since the space of the welding assembly 2 in the base is limited, the installation structure is compact, and the magnetic spring 32 must not only compensate for the gravity of the welding assembly 2, but also ensure the stability of the up and down movement of the welding assembly 2.

[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 movement direction of the mover 322 is parallel to the force direction of the spring 311. In a specific embodiment, the magnetic spring 32 can be fixed at one end of the stator 321 in a single-end fixing manner. The interior of the stator 321 is a hollow structure. The mover 322 is telescopically matched with the stator 321, and the mover 322 moves up and down along the stator 321 through the mutual magnetic force, 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.

[0050] In some specific embodiments, Figure 4 As shown, the magnetic spring 32 can also adopt a double-end fixing method to fix the two ends of the stator 321, and the mover 322 is connected to the second clamp 25 and is sleeved outside the stator 321. The magnetic force between the mover 322 and the stator 321 makes the mover 322 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 a long-stroke welding method. In actual applications, it can be set according to needs to meet application scenarios with different lengths of welding strokes.

[0051] Furthermore, a grating ruler 13 is provided on the inner side of the base 1, and the grating ruler 13 can accurately measure the movement stroke of the welding component 2 to ensure accurate and controllable welding.

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

[0053] In order to ensure the overall up and down movement of the welding assembly, the welding assembly 2 also includes a guide assembly 4, which is arranged between the fixed block 23 and the vertical portion 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 arranged on the vertical portion 11 of the base 1. The slider 41 is slidably connected to the slide rail 42.

[0054] In order 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 downward as a whole to the welding position, the ultrasonic welding head 211 contacts 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 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 contacts the surface of the workpiece. In the first working process, the magnetic spring offsets the gravity of the welding assembly. Since the gravity of the welding assembly is constant, the compensation force of the magnetic spring during the movement process also remains constant.

[0057] In the second working process, the welding assembly continues to be pressed down from the contact position to the welding position, and the ultrasonic welding head presses down 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 wave is started, and the high-frequency electrical energy is converted into mechanical vibration through the transducer, and the high-frequency vibration is transmitted to the ultrasonic welding head through the amplitude modulator. The ultrasonic welding head welds the workpiece under high-frequency vibration. In this working process, the elastic force released by the spring is used to apply welding pressure to the workpiece, so that the welding pressure remains relatively constant.

[0059] The welding pressure during the welding process is analyzed as follows, where F represents the welding pressure on the workpiece, F1 represents the compensation force of the magnetic spring, G represents the deadweight of the welding assembly, F2 represents the force generated by the compression deformation of the spring, F3 represents the display value of the pressure sensor, and f represents the friction between the welding assembly and the guide rail.

[0060] (1) When the compensation force of the magnetic spring is equal to the deadweight of the welding assembly, that is, F1=G, the welding pressure at this time is F=F2+f; wherein F2=F3, that is, F=F3+f.

[0061] (2) When the compensation force of the magnetic spring is greater than the self-weight of the welding assembly, i.e., 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 assembly, i.e., 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 ensured, 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 assembly 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 deformation of the spring 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 to the guiding block 71. The guide rail 72 is arranged along the up and down direction of the frame. The guiding block 71 is slidably matched with the guide rail 72. The base of the ultrasonic unit is connected to the guiding block 71. By driving the guiding block 71 to move up and down along the guide rail 72 through the Z-direction driving mechanism, the ultrasonic unit is further driven 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 assembly will move upward along the guiding assembly 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 assembly 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 assembly.

[0069] It should be noted that in the original text, "传动连接" is an incorrect expression. It should be "drivably connected" or "transmission-connected" etc. The above translation is based on the original text as much as possible while correcting the obvious error.The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. An ultrasonic unit for low-pressure welding, characterized in that: include: A base, comprising a horizontal portion and a vertical portion; A welding assembly, slidably connected to the vertical portion of the base, the welding assembly comprising an ultrasonic triplet group, the ultrasonic triplet group being configured to weld the workpiece; as well as A driving assembly is arranged between the horizontal portion of the base and the ultrasonic triplet group, the driving assembly includes a driving portion and a magnetic spring, the magnetic spring is arranged parallel to the driving portion, the driving portion is configured to provide welding pressure to the ultrasonic triplet group, and the magnetic spring is configured to balance the gravity of the welding assembly.

2. An ultrasonic unit for low-pressure welding according to claim 1, characterized in that: The ultrasonic triple group includes a transducer, an amplitude modulator and an ultrasonic horn, the transducer is connected to the amplitude modulator, and the amplitude modulator is connected to the ultrasonic horn.

3. An ultrasonic unit for low-pressure welding according to claim 2, characterized in that: The welding assembly further comprises a detection member, two ends of which are respectively connected to the horizontal portion of the base and the driving portion.

4. An ultrasonic unit for low-pressure welding according to claim 3, characterized in that: A fixing block is arranged on the ultrasonic horn. The fixing block has a cavity, and the driving part is installed in the cavity.

5. An ultrasonic unit for low-pressure welding according to claim 4, characterized in that: The driving part comprises a spring, and two ends of the spring are respectively connected to the detection element and the ultrasonic welding head.

6. The ultrasonic unit for low-pressure welding according to claim 2, characterized in that: The welding assembly also includes a first clamp, a second clamp and a transition block, the transition block is connected to the ultrasonic triplet, 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.

7. An ultrasonic unit for low-pressure welding according to claim 6, characterized in that: The magnetic spring is installed on the horizontal part of the base, and the magnetic spring is connected to the ultrasonic triple group through the second clamp.

8. The ultrasonic unit for low-pressure welding according to claim 1, characterized in that: The magnetic spring includes a stator and a mover. The mover moves relative to the stator, and the moving direction of the mover is parallel to the force application direction of the driving part.

9. The ultrasonic unit for low-pressure welding according to claim 1, characterized in that: The welding assembly also includes a guide assembly, which includes a slider and a slide rail. The slider is connected to the ultrasonic triplet group, and the slide rail is arranged on the vertical part of the base. The slider is slidably connected to the slide rail.

10. An ultrasonic welding device, characterized in that: It comprises a frame, a Z-direction driving mechanism and the ultrasonic unit according to any one of claims 1 to 9, wherein the Z-direction driving mechanism is mounted on the frame, the Z-direction driving mechanism is connected to the base, and is used to drive the base to move along the Z direction.

Images