Reflow soldering jig

Abstract

The utility model discloses a reflow soldering frock, include: substrate, form with a plurality of containing space, first function spare, form with a plurality of first exhaust portion on first function spare, a plurality of first exhaust portion with a plurality of containing space one to one correspondence, second function spare, be equipped with second exhaust portion on second function spare, and second exhaust portion communicates with a plurality of first exhaust portion, in third direction, first function spare and second function spare with the welding piece between having preset interval, the utility model discloses set up the first exhaust portion and second exhaust portion of intercommunication on first function spare and second function spare respectively, set up the welding piece with first function spare and second function spare between having preset interval, the space of preset interval includes and forms exhaust passage with first exhaust portion, second exhaust portion, when welding, can inject reducing material through exhaust passage, reduce welding surface oxide, and the gas produced after reduction can also be discharged through exhaust passage, be favorable to the promotion welding efficiency.

Description

Technical Field

[0001] This utility model relates to the field of reflow soldering technology, and in particular to a reflow soldering fixture. Background Technology

[0002] In recent years, as power semiconductor devices have evolved towards higher current and higher power density, MOSFETs, IGBTs, and other chips have commonly adopted vacuum reflow or protective atmosphere reflow processes for one-time multi-chip soldering during the packaging stage. To balance production capacity and positioning accuracy, production lines typically use "complete carrier equipment" (also known as "soldering trays") to clamp, transport, and heat-treat the entire substrate and the chips on it.

[0003] However, existing complete sets of carriers have the following defects in actual mass production: (1) Since the carrier and chip contact position are not reserved for reduction and exhaust channels, the bubble rate is high, which can easily lead to welding deformation and poor welding quality; (2) The complete set structure will deform after repeated disassembly and assembly, resulting in a short service life and high manufacturing cost. Utility Model Content

[0004] The purpose of this invention is to provide a reflow soldering fixture to solve the problem of high bubble rate at the contact position between the carrier and the chip, which leads to easy deformation during soldering, thereby improving soldering efficiency, extending service life, and reducing manufacturing costs.

[0005] This utility model provides a reflow soldering fixture, including:

[0006] A substrate having a plurality of receiving spaces formed thereon for receiving components to be welded;

[0007] The first functional component includes at least two components, which are disposed on opposite sides of the substrate in a first direction. A plurality of first exhaust portions are formed on the first functional component, and each first exhaust portion corresponds to at least one of the receiving spaces.

[0008] The second functional component is disposed between the two first functional components. The second functional component extends along a second direction, which is orthogonal to the first direction. In the first direction, the second functional component abuts against the two first functional components respectively. The second functional component is provided with a second exhaust portion, which communicates with a plurality of first exhaust portions.

[0009] in:

[0010] In the third direction, there is a preset distance between the first functional component and the component to be welded, and the third direction is perpendicular to the plane formed by the first direction and the second direction.

[0011] In the reflow soldering fixture described above, preferably, the first venting portion includes a plurality of grooves, the grooves being formed by recesses from the side of the first functional component along the first direction, and the plurality of grooves being spaced apart on the first functional component along the second direction.

[0012] In the reflow soldering fixture described above, preferably, the second venting section includes a plurality of through holes, the through holes penetrating the second functional component along the third direction, and the plurality of through holes being disposed on the second functional component along the second direction.

[0013] In the reflow soldering fixture described above, preferably, at least one first positioning part is provided on the substrate, and at least one first functional component is provided with a first positioning mating part, wherein the first positioning part and the first positioning part can form a positioning mating.

[0014] In the reflow soldering fixture described above, preferably, the first positioning portion includes a first positioning groove formed by a recess in the surface of the substrate along the third direction, the first positioning groove penetrating the substrate along the first direction, and the first positioning mating portion includes a first positioning block located on the side of the first functional member opposite to the first vent portion, and in the first direction, the first positioning block extends into the first positioning groove to form a positioning mating.

[0015] In the reflow soldering fixture described above, preferably, the second functional component is provided with a second positioning part, and the first functional component is provided with a second positioning mating part, wherein the second positioning part can form a positioning mating with the second positioning mating part.

[0016] In the reflow soldering fixture described above, preferably, the second positioning part includes a plurality of second positioning grooves, the second positioning grooves are recessed along the first direction, the plurality of second positioning grooves are spaced apart along the second direction, and the second positioning mating part includes a plurality of second positioning blocks, the plurality of second positioning grooves correspond one-to-one with the plurality of second positioning blocks, and in the first direction, the second positioning block can extend into the corresponding second positioning groove to form a positioning mating.

[0017] In the reflow soldering fixture described above, preferably, a through groove is provided on the substrate along the third direction, and a plurality of first limiting blocks are provided in the through groove. The first limiting blocks extend along the first direction, and the plurality of first limiting blocks are spaced apart along the second direction. Along the first direction, each first limiting block is provided with a plurality of second limiting blocks, and the second limiting blocks and the first limiting blocks enclose the receiving space.

[0018] In the reflow soldering fixture described above, preferably, the reflow soldering fixture further includes a limiting member, the limiting member being disposed on the side of the substrate away from the first functional member and the second functional member, the limiting member abutting against the workpiece to be soldered, the limiting member being used to restrict the workpiece to be soldered from moving upward in the third direction.

[0019] In the reflow soldering fixture described above, preferably, the limiting member includes a plurality of protrusions extending along the third direction, the plurality of protrusions being spaced apart along the second direction, the plurality of protrusions corresponding one-to-one with a plurality of the workpieces to be welded, and each protrusion abutting against the corresponding workpiece to be welded.

[0020] Compared with the prior art, this utility model provides a first exhaust section and a second exhaust section that are interconnected on the first functional component and the second functional component, respectively. At the same time, a preset distance is provided between the workpiece to be welded and the first and second functional components. The space included in the preset distance, together with the first exhaust section and the second exhaust section, forms an exhaust channel. During welding, a reducing substance can be injected through the exhaust channel to reduce the oxide on the welding surface. At the same time, the gas generated after reduction can also be discharged through the exhaust channel, which helps to improve welding efficiency and reduce the bubble rate on the welding surface. Attached Figure Description

[0021] Figure 1 This is a perspective view of the reflow soldering fixture provided in an embodiment of this utility model;

[0022] Figure 2 This is a side view of the reflow soldering fixture provided in an embodiment of this utility model;

[0023] Figure 3 This is a perspective view of the first functional component provided in an embodiment of the present utility model;

[0024] Figure 4 This is a top view of the second functional component provided in an embodiment of this utility model;

[0025] Figure 5 This is a perspective view of the substrate provided in an embodiment of the present invention;

[0026] Figure 6 This is a top view of the substrate provided in an embodiment of this utility model;

[0027] Figure 7 This is a perspective view of the limiting member provided in an embodiment of this utility model.

[0028] Explanation of reference numerals in the attached figures:

[0029] 10-Substrate, 11-Accommodation space, 12-First positioning part, 121-First positioning groove, 13-Through groove, 14-First limiting block, 15-Second limiting block;

[0030] 20-First functional component, 21-First exhaust part, 211-Groove, 22-First positioning mating part, 221-First positioning block, 23-Second positioning mating part, 231-Second positioning block;

[0031] 30 - Second functional component, 31 - Second exhaust part, 311 - Through hole, 32 - Second positioning part, 321 - Second positioning groove;

[0032] 40 - Limiting component, 41 - Protrusion, 411 - Weight reduction hole;

[0033] 50-Exhaust space;

[0034] D1 - First direction, D2 - Second direction, D3 - Third direction. Detailed Implementation

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the existing technology, during the welding process of the parts to be welded, on the one hand, welding oxides are generated on the welding surface between the parts to be welded and the solder, which affects the welding effect; on the other hand, since the existing reflow soldering fixtures do not have reserved exhaust channels, the bubbles generated during the welding process cannot be discharged, further affecting the welding effect.

[0037] To solve the above problems, refer to Figure 1 As shown, this utility model provides a reflow soldering fixture, including a substrate 10, a first functional component 20, and a second functional component 30, wherein:

[0038] A plurality of receiving spaces 11 are formed on the substrate 10. The receiving spaces 11 are used to receive the components to be soldered. Multiple components to be soldered can be assembled on the substrate 10. The reflow soldering fixture of this application can be applied to the soldering of MOSFET devices. Before soldering, the MOSFET chip needs to be installed in the receiving space 11.

[0039] The first functional component 20 includes at least two components, which are disposed on opposite sides of the substrate 10 in the first direction D1. A plurality of first venting portions 21 are formed on each first functional component 20, and each first venting portion 21 corresponds to at least one receiving space 11. The first direction D1 is the width direction of the substrate 10. The two first functional components 20 abut against opposite sides of the substrate 10 in the width direction, and thus the two first functional components 20 correspond to two rows of components to be soldered. Air bubbles generated during the soldering process between the components and the solder can be discharged through the first venting portions 21. One first venting portion 21 can be provided corresponding to one receiving space 11, or one first venting portion 21 can be provided corresponding to multiple receiving spaces 11, so that each component to be soldered in each receiving space 11 is provided with a corresponding first venting portion 21.

[0040] The second functional component 30 is disposed between the two first functional components 20. The second functional component 30 extends along the second direction D2, which is orthogonal to the first direction D1. The second direction D2 is the length direction of the substrate 10. On the first direction D1, the second functional component 30 abuts against the two first functional components 20 respectively. That is, the two first functional components 20 and the second functional component 30 abut against each other in the width direction of the substrate 10 in sequence, so as to fix the first functional component 20 and the second functional component 30 on the substrate 10 without the need for other components to fix them.

[0041] Reference Figure 4 As shown, the second functional component 30 is provided with a second exhaust section 31, which is connected to a plurality of first exhaust sections 21. The gas discharged from the first exhaust section 21 is then discharged through the second exhaust section 31, which can reduce the bubble rate of welding and improve the welding effect.

[0042] In the embodiments provided in this application, reference is made to Figure 2 As shown, in the third direction D3, there is a preset distance between the first functional component 20 and the workpiece to be welded. The third direction D3 is perpendicular to the plane formed by the first direction D1 and the second direction D2. The third direction D3 is parallel to the direction of gravity. When the workpiece to be welded, the first functional component 20, and the second functional component 30 are all mounted on the substrate 10, the first functional component 20 and the second functional component 30 are in the same plane. In the third direction D3, there is a certain distance between the workpiece to be welded and the first functional component 20. Therefore, there is a certain space between all the workpieces to be welded and the first functional component 20. This space is the exhaust space 50. The exhaust space 50 is connected to the first exhaust section 21. Therefore, the exhaust space 50, the first exhaust section 21, and the second exhaust section 31 form an exhaust channel. The bubbles generated during welding can be discharged through the exhaust space 50, the first exhaust section 21, and the second exhaust section 31 to reduce the welding bubble rate.

[0043] Furthermore, since welding oxides are generated on the welding surface during the welding process, in order to improve welding efficiency and reduce the impact of welding oxides on the welding effect, reducing substances can be injected into the reflow welding fixture through the second exhaust section 31, the first exhaust section 21 and the exhaust space 50, so that the welding oxides are reduced. The gas generated after reduction can be discharged through the exhaust space 50, the first exhaust section 21 and the second exhaust section 31, thereby reducing the welding oxides on the welding surface and improving welding efficiency.

[0044] The reflow soldering fixture of this application has reserved channels for injecting reducing substances and venting gases, which can effectively improve welding efficiency and reduce the bubble rate. After the first functional component 20 and the second functional component 30 are installed on the substrate 10, they can restrict the movement of the workpiece to be soldered in the third direction D3, thereby preventing the workpiece from shifting in position in the third direction D3 due to thermal expansion and contraction during welding, which is beneficial to improving welding efficiency. The first functional component 20 and the second functional component 30 are fixed to the substrate 10 by mutual abutment, which provides a stable fixing effect and is easy to disassemble and install, eliminating the need for bolts and other components for installation, thus reducing the manufacturing cost of the fixture.

[0045] In one feasible implementation, refer to Figure 1 and Figure 3 As shown, the first venting section 21 includes a plurality of grooves 211. The grooves 211 are recessed along the first direction D1 by the side of the first functional member 20. When the first functional member 20 is mounted on the substrate 10, the grooves 211 are located on the side of the first functional member 20 away from the substrate 10. The plurality of grooves 211 are spaced apart on the first functional member 20 along the second direction D2. During the welding process, the workpiece to be welded in the receiving space 11 corresponds to the groove 211, and the position of each groove 211 corresponds to the welding surface of the workpiece to be welded and the solder. The groove 211 is located above the workpiece to be welded in the third direction D3, so that the bubbles generated during the welding process move directly upward and flow to the second venting section 31 through the groove 211. The plurality of grooves 211 form a "tooth-shaped" notch on the first functional member 20, so that each workpiece to be welded has a corresponding notch for venting, and the venting process between adjacent workpieces to be welded does not interfere with each other.

[0046] Furthermore, referring to Figure 4 As shown, the second exhaust section 31 includes several through holes 311, which penetrate the second functional component 30 along a third direction D3, and are disposed on the second functional component 30 along a second direction D2. Gas is collected from the grooves 211 on both sides into the second functional component 30, and can immediately continue to be discharged upward from the surface of the tooling along the third direction D3. The discharge path is short and the exhaust resistance is small, which helps to improve the exhaust efficiency and keep the welding bubble rate at a low percentage.

[0047] Since several through holes 311 are arranged along the length direction of the substrate 10, after the gas generated during the welding of the workpiece is discharged through the corresponding groove 211, there is at least one through hole 311 corresponding to it. Therefore, no matter where the workpiece is located in the second direction D2, it can be discharged smoothly. The discharge distance of each workpiece is equal and there is no dead corner for discharge.

[0048] To improve the stability of the first functional component 20 and the second functional component 30 on the substrate 10, refer to Figure 1 As shown, the substrate 10 is provided with at least one first positioning part 12, and at least one first functional component 20 is provided with a first positioning engagement part 22. The first positioning part 12 and the first positioning engagement part 22 can form a positioning engagement. When the first functional component 20 and the second functional component 30 are sequentially mounted on the substrate 10, the positioning engagement of at least one first positioning part 12 and one first positioning engagement part 22 locks the first functional component 20 and the second functional component 30 on the substrate 10, so that the first functional component 20 and the second functional component 30 cannot shake, and even if they are subjected to impact or vibration, the positions of the first functional component 20 and the second functional component 30 can remain stable.

[0049] Specifically, refer to Figure 6 As shown, the first positioning part 12 includes a first positioning groove 121 formed by recessing the surface of the substrate 10 along a third direction D3. The first positioning groove 121 penetrates the substrate 10 along a first direction D1. (Refer to...) Figure 3 As shown, the first positioning and mating part 22 includes a first positioning block 221, which is located on the side of the first functional member 20 away from the first exhaust part 21 in the first direction D1. The first positioning block 221 extends into the first positioning groove 121 to form a positioning fit. When fixing the first functional member 20, the first positioning block 221 is inserted into the first positioning groove 121 along the first direction D1 until the first functional member 20 abuts against the substrate 10, so as to realize the positioning of the first functional member 20 in the first direction D1 and the second direction D2, thereby locking the position of the first functional member 20 in the plane formed by the first direction D1 and the second direction D2, so that the first functional member 20 cannot wobble.

[0050] Since the second functional component 30 and the first functional component 20 are fixed to the substrate 10 by mutual abutment, the first functional component 20 is locked by the positioning engagement of the first positioning part 12 and the first positioning mating part 22. However, there is a possibility that the second functional component 30 may slip relative to the first functional component 20 in the second direction D2. Therefore, it is necessary to improve the stability of the connection between the first functional component 20 and the second functional component 30. (Refer to...) Figure 4 As shown, the second functional component 30 is provided with a second positioning part 32, referring to... Figure 3As shown, the first functional component 20 is provided with a second positioning engagement part 23, and the second positioning part 32 can form a positioning engagement with the second positioning engagement part 23. Through the positioning engagement between the second positioning part 32 and the second positioning engagement part 23, the second functional component 30 is locked and connected to the first functional component 20, so as to restrict the second functional component 30 from sliding relative to the first functional component 20 along the second direction D2.

[0051] Specifically, the second positioning part 32 includes a plurality of second positioning grooves 321, which are recessed along the first direction D1. The plurality of second positioning grooves 321 are spaced apart along the second direction D2. The second positioning mating part 23 includes a plurality of second positioning blocks 231, with each of the plurality of second positioning grooves 321 corresponding to one of the plurality of second positioning blocks 231. In the first direction D1, the second positioning blocks 231 can extend into the corresponding second positioning grooves 321 to form a positioning fit. On the first functional member 20, the solid portion between adjacent grooves 211 forms a second positioning block 231. The second positioning block 231 can be inserted into the corresponding second positioning groove 321 in the first direction D1, thereby locking the relative positions of the second functional member 30 and the first functional member 20 in the first direction D1 and the second direction D2, effectively preventing the second functional member 30 from sliding along the second direction D2.

[0052] During the welding process, the melting of the solder may cause the part to shift within the receiving space 11. To limit the movement of the part, in the embodiments provided in this application, reference is made to... Figure 5 and Figure 6 As shown, a through groove 13 is provided on the substrate 10 along the third direction D3. A plurality of first limiting blocks 14 are provided in the through groove 13. The first limiting blocks 14 extend along the first direction D1. The plurality of first limiting blocks 14 are spaced apart along the second direction D2. Along the first direction D1, each first limiting block 14 is provided with a plurality of second limiting blocks 15. The second limiting blocks 15 and the first limiting blocks 14 enclose and form an accommodating space 11.

[0053] At least two receiving spaces 11 can be formed between two adjacent first limiting blocks 14. The first limiting block 14 can restrict the workpiece to be welded in the receiving space 11 from shifting in the second direction D2. The second limiting block 15 is used to restrict the workpiece to be welded in the receiving space 11 from shifting in the first direction D1, thereby fixing the workpiece to be welded in the corresponding receiving space 11.

[0054] The first functional component 20 and the second functional component 30 can restrict the offset of the workpiece to be welded along the third direction D3, but can only restrict the workpiece to be welded from moving upwards along the third direction D3. In order to restrict the workpiece to be welded from moving downwards along the third direction D3, refer to... Figure 1 and Figure 2As shown, the reflow soldering fixture also includes a limiting member 40. The limiting member 40 is disposed on the side of the substrate 10 opposite to the first functional member 20 and the second functional member 30. The limiting member 40 abuts against the workpiece to be soldered and is used to restrict the movement of the workpiece to be soldered in the third direction D3. The limiting member 40 extends along the second direction D2, so that the limiting member 40 can contact all the workpieces to be soldered. Thus, under the combined action of the first functional member 20, the second functional member 30, and the limiting member 40, the up-and-down movement of the workpieces to be soldered along the third direction D3 during the soldering process is restricted, so as to ensure that the soldering effect of all the workpieces to be soldered is consistent.

[0055] In one feasible implementation, refer to Figure 7 As shown, the limiting member 40 includes several protrusions 41 extending along a third direction D3 and spaced apart along a second direction D2. Each protrusion 41 corresponds one-to-one with a component to be welded, and each protrusion 41 abuts against its corresponding component. This method of one-to-one correspondence between protrusions 41 and components to be welded achieves independent limiting, locally absorbing thickness differences in individual components and preventing errors from being transmitted to adjacent components. This results in higher coplanarity of all components after welding.

[0056] Furthermore, multiple protrusions 41 are arranged at intervals to form a limiting member 40, and there is a gap between adjacent protrusions 41. This gap is conducive to protecting the free flow of welding atmosphere, and the back side of the workpiece to be welded can also be surrounded by welding atmosphere, reducing the risk of secondary oxidation.

[0057] Furthermore, multiple protrusions 41 form a "comb" structure for the limiting member 40, which enables the overall structure of the limiting member 40 to be lightweight.

[0058] Each protrusion 41 is also provided with a weight reduction hole 411. The weight reduction hole 411 is formed by a downward indentation from the surface of the protrusion 41 along the third direction D3. The solid part of the outer periphery of the weight reduction hole 411 can abut against the workpiece to be welded to limit the workpiece to be welded. Under the premise of performing the limiting function, the setting of the weight reduction hole 411 can further reduce the weight of the limiting part 40, realizing the lightweight design of the reflow soldering fixture.

[0059] Based on the above embodiments, the reflow soldering fixture of this utility model is used for soldering MOS transistor devices. In the reflow soldering fixture, two accommodating spaces 11 are formed between two adjacent first limiting blocks 14 on the substrate 10. Therefore, two rows of MOS chips can be assembled along the second direction D2 (the length direction of the substrate 10).

[0060] The assembly process of the reflow soldering fixture in this application is as follows: two first functional components 20 are arranged sequentially along the second direction D2, and two first functional components 20 are arranged along the first direction D1 to correspond to two rows of MOS chips. A second functional component 30 is arranged between the two first functional components 20 to meet the requirements of soldering a large number of MOS chips.

[0061] After the MOS chip, the first functional component 20 and the second functional component 30 are assembled, the limiting component 40 is installed on the side of the MOS chip away from the first functional component 20 and the second functional component 30. The limiting component 40 includes two components, which are installed side by side along the first direction D1 to simultaneously limit the MOS chips on both sides.

[0062] The above description, based on the embodiments shown in the drawings, details the structure, features, and effects of this utility model. The above description is only a preferred embodiment of this utility model, but the scope of implementation of this utility model is not limited to what is shown in the drawings. Any changes made in accordance with the concept of this utility model, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, shall be within the protection scope of this utility model.

Claims

1. A reflow soldering fixture, characterized in that, include: A substrate having a plurality of receiving spaces formed thereon for receiving components to be welded; The first functional component includes at least two components, which are disposed on opposite sides of the substrate in a first direction. A plurality of first exhaust portions are formed on the first functional component, and each first exhaust portion corresponds to at least one of the receiving spaces. The second functional component is disposed between the two first functional components. The second functional component extends along a second direction, which is orthogonal to the first direction. In the first direction, the second functional component abuts against the two first functional components respectively. The second functional component is provided with a second exhaust portion, which communicates with a plurality of first exhaust portions. in: In the third direction, there is a preset distance between the first functional component and the component to be welded, and the third direction is perpendicular to the plane formed by the first direction and the second direction.

2. The reflow soldering fixture according to claim 1, characterized in that, The first exhaust portion includes a plurality of grooves, which are formed by recesses from the side of the first functional component along the first direction, and the plurality of grooves are spaced apart on the first functional component along the second direction.

3. The reflow soldering fixture according to claim 1, characterized in that, The second exhaust portion includes a plurality of through holes, which penetrate the second functional component along the third direction, and the plurality of through holes are disposed on the second functional component along the second direction.

4. The reflow soldering fixture according to claim 1, characterized in that, The substrate is provided with at least one first positioning part, and at least one first functional component is provided with a first positioning engagement part, wherein the first positioning part and the first positioning part can form a positioning engagement.

5. The reflow soldering fixture according to claim 4, characterized in that, The first positioning portion includes a first positioning groove formed by a recess in the surface of the substrate along the third direction. The first positioning groove penetrates the substrate along the first direction. The first positioning mating portion includes a first positioning block. The first positioning block is located on the side of the first functional member opposite to the first exhaust portion. In the first direction, the first positioning block extends into the first positioning groove to form a positioning mating.

6. The reflow soldering fixture according to claim 1, characterized in that, The second functional component is provided with a second positioning part, and the first functional component is provided with a second positioning mating part. The second positioning part can form a positioning mating with the second positioning mating part.

7. The reflow soldering fixture according to claim 6, characterized in that, The second positioning part includes a plurality of second positioning grooves, which are recessed along the first direction. The plurality of second positioning grooves are spaced apart along the second direction. The second positioning mating part includes a plurality of second positioning blocks, which correspond one-to-one with the plurality of second positioning grooves. In the first direction, the second positioning block can extend into the corresponding second positioning groove to form a positioning mating.

8. The reflow soldering fixture according to claim 1, characterized in that, Along the third direction, a through groove is provided on the substrate, and a plurality of first limiting blocks are provided in the through groove. The first limiting blocks extend along the first direction, and the plurality of first limiting blocks are spaced apart along the second direction. Along the first direction, each first limiting block is provided with a plurality of second limiting blocks, and the second limiting blocks and the first limiting blocks enclose the accommodating space.

9. The reflow soldering fixture according to claim 1, characterized in that, The reflow soldering fixture further includes a limiting member, which is disposed on the side of the substrate away from the first functional component and the second functional component. The limiting member abuts against the workpiece to be soldered and is used to restrict the workpiece to be soldered from moving upward in the third direction.

10. The reflow soldering fixture according to claim 9, characterized in that, The limiting member includes a plurality of protrusions extending along the third direction, the plurality of protrusions being spaced apart along the second direction, the plurality of protrusions corresponding one-to-one with the plurality of the workpieces to be welded, and each protrusion abutting against the corresponding workpiece to be welded.

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