A double-elastic fisheye terminal for IGBT modules and its manufacturing process

Abstract

This invention relates to the field of IGBT power module connection technology, and in particular to a dual-elastic fisheye terminal for IGBT modules and its manufacturing process. The terminal includes a pin, a fisheye segment, a first elastic segment, a second elastic segment, and a mounting base connected in sequence. The pin is used for insertion into a PCB board, and the fisheye segment is used for insertion into a socket on the PCB board. The first elastic segment includes a first elastic flap and a second elastic flap arranged in parallel or connected in sequence. The second elastic segment includes a first bent flap and a second bent flap connected in sequence. The end of the first bent flap away from the second bent flap is connected to the first elastic segment, and the end of the second bent flap away from the first bent flap is connected to the mounting base. The mounting base is used for connection to the IGBT module. This invention improves the stability of the terminal under high temperature, vibration, and thermal cycling conditions through the synergistic effect of the dual elastic structure, ensuring a durable and reliable connection between the IGBT module and the PCB board, and reducing the risk of failure.

Description

Technical Field

[0001] This invention relates to the field of IGBT power module connection technology, and in particular to a double elastic fisheye terminal for IGBT modules and its manufacturing process. Background Technology

[0002] As a core power device in the field of power electronics, IGBT modules are widely used in complex environments with high temperature, high frequency vibration, frequent thermal cycling, and the potential presence of corrosive gases. Fisheye terminals, due to their advantages of solderless press-fitting and efficient assembly, have become an important component for connecting IGBT modules to the PCB board. However, the reliability of this connection directly determines the operational stability of the IGBT module, making them particularly suitable for solderless press-fitting connections between IGBT modules and PCB boards in scenarios such as new energy vehicles, industrial converters, and inverters.

[0003] Existing fisheye terminals mostly employ a single elastic arm structure, achieving contact and fixation with PCB board holes through a single elastic deformation. During long-term operation of IGBT modules, frequent temperature shocks (such as thermal cycling from -40℃ to 150℃) can lead to elastic fatigue of the terminal material. External vibrations can easily cause the contact gap to widen, resulting in increased contact resistance, signal interruption, or even connection failure. At the same time, the single elastic structure has limited ability to compensate for thermal deformation and cannot adapt to the differences in thermal expansion and contraction during IGBT module operation, further reducing connection reliability and limiting the service life of IGBT modules in high-end industrial and new energy fields. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a double elastic fisheye terminal for IGBT modules and its manufacturing process. This invention improves the stability of the terminal under high temperature, vibration and thermal cycling conditions through the synergistic effect of the double elastic structure, ensures the long-lasting and reliable connection between the IGBT module and the PCB board, and reduces the risk of failure.

[0005] The technical solution adopted in this invention is as follows: A dual-elastic fisheye terminal for an IGBT module includes a pin, a fisheye segment, a first elastic segment, a second elastic segment, and a fixing base connected in sequence. The pin is used to insert into a PCB board, and the fisheye segment is used to engage with a socket on the PCB board. The first elastic segment includes a first elastic flap and a second elastic flap arranged in parallel or connected in sequence. The second elastic segment includes a first bent flap and a second bent flap connected in sequence. The end of the first bent flap away from the second bent flap is connected to the first elastic segment, and the end of the second bent flap away from the first bent flap is connected to the fixing base. The fixing base is used to connect to the IGBT module. The fisheye segment has a fisheye hole extending through its side. Within the fisheye hole, there is at least one vertical beam and at least two horizontal beams. The vertical beam is coaxial with the fisheye segment. The two horizontal beams are spaced apart on the vertical beam, dividing the horizontal beams into a first elastic folded beam and a second elastic folded beam. Both the first and second elastic folded beams have bends, and the bends of the first and second elastic folded beams are in opposite directions. The bends of the two horizontal beams are also in opposite directions. The inner wall of the fisheye hole also has at least two vertical holes for inserting the two ends of the vertical beams and at least four... The transverse beams have a first and a second insertion strip cut and bent at both ends for interlocking with the transverse hole. The bending directions of the first and second insertion strips are opposite and their ends are close to each other. The first and second insertion strips are punched with a first abutment piece and a second abutment piece for abutting against the inner wall of the transverse hole. The first and second abutment pieces are respectively raised in the bending direction of the first and second insertion strips. When the vertical beam and the two transverse beams are installed in the fish-eye hole, a vertical gap is formed between the vertical beam and the corresponding vertical hole.

[0006] The first elastic flap has at least one first crease, and the second elastic flap has at least one second crease. The bending directions of the first elastic flap and the second elastic flap are the same or opposite. When the bending directions of the first elastic flap and the second elastic flap are opposite, a lateral deformation range is formed between the first crease and the second crease.

[0007] The first elastic segment also includes a support column disposed between the first elastic flap and the second elastic flap, one end of the support column being fixedly connected to the fisheye segment and the other end having a gap with the second elastic segment.

[0008] There are gaps between the support column and the first elastic flap, as well as between the support column and the second elastic flap.

[0009] The second elastic segment includes two parallel first curved pieces, which are simultaneously connected between the first elastic segment and the second curved piece, and a gap is formed between the two first curved pieces. The second curved piece is connected at the position of the gap.

[0010] The bending directions of the first bent piece and the second bent piece are opposite.

[0011] The needle tip has guide bevels on all four sides, and the fisheye segment includes a straight segment in the middle. The straight segment is surrounded by horizontal planes, and the left and right sides of the straight segment are each provided with at least two chamfers. It also includes a connecting section between the first elastic segment and the second elastic segment, and a positioning boss is provided on each side of the connecting section.

[0012] The second elastic segment includes a first S-shaped bending piece and two first support pieces. The two first support pieces are symmetrically distributed on both sides of the first S-shaped bending piece. The first S-shaped bending piece is connected between the first elastic segment and the fixed base. One end of each of the two first support pieces is fixedly connected to the first elastic segment, and a first buffer zone is provided between the other end of each of the two first support pieces and the fixed base. Several welding points are provided on the bottom surface of the fixed base.

[0013] The second elastic segment includes a second support piece and two second S-shaped bending pieces. The two second S-shaped bending pieces are symmetrically distributed on both sides of the second support piece, and the two second S-shaped bending pieces are connected and disposed between the first elastic segment and the fixed seat. One end of the second support piece is fixedly connected to the first elastic segment, and a second buffer space is provided between the other end and the fixed seat. Several welding points are provided on the bottom surface of the fixed seat.

[0014] A manufacturing process for a double-elastic fisheye terminal for an IGBT module includes the following steps: S1: Feed the strip into the continuous die and perform the first punching process to punch out the two-dimensional outer contour unfolded view of the fisheye terminal. Punch out the fisheye hole in the fisheye section. Punch out the first elastic fold, support column and second elastic fold in parallel distribution in the first elastic section. Punch out the waste material on both sides of the support column and one end near the connecting section to form gaps and gaps. Punch out the positioning boss in the connecting section. Punch out two first curved pieces and second curved pieces in the second elastic section. Punch out the waste material between the two first curved pieces to form a gap. At the same time, punch out the outer contour of the fixing seat. S2: The conveyor belt undergoes a second extrusion molding process, where guide slopes are extruded and molded around the needle tip, chamfers are extruded and molded on both sides of the straight section, and several raised welding points are extruded and molded on the fixed seat. S3: Continue conveying the material belt for the third three-dimensional bending and forming process. Press creases with opposite bending directions on the first elastic fold and the second elastic fold respectively. Bend the first and second bending pieces in the opposite direction to form an S-shaped structure. At the same time, bend the fixing seat to be relatively perpendicular to the connecting section, and the welding point is located on the side of the fixing seat away from the second elastic section. S4: Perform the electroplating process, feeding the one-piece stamped fisheye terminal strip into the electroplating line for overall or partial tin plating or gold plating. S5: Perform the cutting and separation process, and make the fisheye terminal form an independent unit by cutting the connecting ribs at the edge of the strip; S6: Conduct pressure stability and long-term vibration condition tests, and measure the ultimate deformation resistance of the fisheye terminal and the wear condition of the outer surface of the fisheye section.

[0015] The beneficial effects of this invention are as follows: This invention constructs a dual elastic compensation structure by sequentially connecting the elastic flap of the first elastic segment and the bending flap of the second elastic segment. Compared with the existing single elastic arm fisheye terminal, it significantly improves the elastic deformation redundancy and deformation recovery capability of the terminal, effectively alleviating material elastic fatigue under frequent thermal cycling and high-frequency vibration conditions during long-term operation of the IGBT module, avoiding the expansion of the insertion contact gap, stabilizing the contact resistance, and fundamentally reducing the risk of signal interruption and connection failure. At the same time, it has excellent thermal deformation compensation capability, which can effectively adapt to the thermal expansion and contraction differences caused by wide-temperature thermal cycling during the operation of the IGBT module, maintaining stable insertion contact pressure throughout the process, ensuring the connection reliability between the IGBT module and the PCB board. The dual elastic structure can also disperse the structural stress under high-frequency vibration and impact conditions, avoiding the stress concentration problem that is prone to occur in the single elastic arm structure. It significantly improves the vibration resistance and structural stability of the terminal in complex scenarios such as new energy vehicles, industrial converters, and inverters, and extends the overall service life of the IGBT module. At the same time, it fully retains the core advantages of fisheye terminals, such as solderless press-fitting and efficient assembly. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a front view schematic diagram of the present invention; Figure 3 for Figure 2 A magnified view of a portion of point A in the middle; Figure 4 This is a right-side view of the present invention with the support column removed; Figure 5 This is a structural schematic diagram from another perspective of the present invention; Figure 6 This is a schematic diagram of the structure of the second embodiment of the present invention; Figure 7 This is a structural schematic diagram from another perspective of the second embodiment; Figure 8 This is a schematic diagram of the structure of the third embodiment of the present invention; Figure 9 This is a schematic diagram of the corresponding fisheye segment of the present invention; Figure 10 for Figure 9A magnified view of a portion of point B in the middle; Figure 11 This is a cross-sectional schematic diagram of the fisheye segment in this invention; Figure 12 This is a cross-sectional schematic diagram of the fisheye segment from another perspective in this invention; Figure 13 This is a partial structural schematic diagram of the transverse beam in this invention; In the diagram, 1-needle tip, 2-fisheye segment, 3-first elastic segment, 4-second elastic segment, 5-fixing base, 6-first elastic flap, 7-second elastic flap, 8-first bending piece, 9-second bending piece, 10-first crease, 11-second crease, 12-lateral deformation range, 13-support column, 14-gap, 15-slit, 16-void, 17-guide slope, 18-connecting segment, 19-positioning boss, 20-first S-shaped bending piece, 21-first support piece. 22-First buffer zone, 23-Second support piece, 24-Second S-shaped curved piece, 25-Second buffer zone, 26-Weld point, 27-Straight segment, 28-Chamfer, 29-Fisheye hole, 30-Vertical beam, 31-Horizontal beam, 32-First elastic folded beam, 33-Second elastic folded beam, 34-Angle, 35-Vertical hole, 36-Horizontal hole, 37-First connector strip, 38-Second connector strip, 39-First abutment piece, 40-Second abutment piece, 41-Vertical gap. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0019] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0020] The directional and positional terms used in this invention, such as "up," "down," "front," "back," "left," "right," "inner," "outer," "top," "bottom," and "side," are merely for reference to the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding this invention, and not for limiting the scope of protection of this invention.

[0021] like Figures 1 to 5As shown in the figure, an embodiment of the present invention provides a dual-elastic fisheye terminal for an IGBT module, comprising a pin 1, a fisheye segment 2, a first elastic segment 3, a second elastic segment 4, and a fixing base 5 connected in sequence. The pin 1 is used to insert into a PCB board, and the fisheye segment 2 is used to engage with a socket on the PCB board. The first elastic segment 3 includes a first elastic flap 6 and a second elastic flap 7 arranged in parallel or connected in sequence. The second elastic segment 4 includes a first bent piece 8 and a second bent piece 9 connected in sequence. The end of the first bent piece 8 away from the second bent piece 9 is connected to the first elastic segment 3, and the end of the second bent piece 9 away from the first bent piece 8 is connected to the fixing base 5. The fixing base 5 is used to connect to the IGBT module.

[0022] The beneficial effects of this design are as follows: This invention constructs a dual elastic compensation structure by sequentially connecting the elastic flaps of the first elastic segment and the bending flaps of the second elastic segment. Compared with existing single elastic arm fisheye terminals, this significantly improves the elastic deformation redundancy and deformation recovery capability of the terminal, effectively alleviating material elastic fatigue under frequent thermal cycling and high-frequency vibration conditions during long-term operation of the IGBT module, preventing the expansion of the insertion contact gap, stabilizing the contact resistance, and fundamentally reducing the risk of signal interruption and connection failure. At the same time, it has excellent thermal deformation compensation capability, which can effectively adapt to the thermal expansion and contraction differences caused by wide temperature range thermal cycling of the IGBT module during operation, such as -40℃ to 150℃, maintaining stable insertion contact pressure throughout the process, ensuring the connection reliability between the IGBT module and the PCB board. The dual elastic structure can also disperse the structural stress under high-frequency vibration and impact conditions, avoiding the stress concentration problem that is prone to occur in single elastic arm structures. This significantly improves the vibration resistance and structural stability of the terminal in complex scenarios such as new energy vehicles, industrial converters, and inverters, extending the overall service life of the IGBT module, while fully retaining the core advantages of fisheye terminals such as solderless press-fitting and efficient assembly.

[0023] like Figures 9 to 13As shown, a fisheye hole 29 penetrates the side of the fisheye segment 2. At least one vertical beam 30 and at least two horizontal beams 31 are provided within the fisheye hole 29. The vertical beam 30 is coaxial with the fisheye segment 2. The two horizontal beams 31 are spaced apart on the vertical beam 30. The vertical beam 30 divides the horizontal beams 31 into a first elastic folded beam 32 and a second elastic folded beam 33. Both the first elastic folded beam 32 and the second elastic folded beam 33 have bends 34, and the bends 34 of the first elastic folded beam 32 and the second elastic folded beam 33 are in opposite directions. The bends 34 of the two horizontal beams 31 are also in opposite directions. The inner wall of the fisheye hole 29 also has at least two vertical holes 35 for the two ends of the vertical beam 30 to be inserted into, and at least... Four transverse holes 36, each of the transverse beams 31 has a first insertion strip 37 and a second insertion strip 38 cut and bent at both ends for insertion into the transverse holes 36. The bending directions of the first insertion strip 37 and the second insertion strip 38 are opposite and their ends are close to each other. The first insertion strip 37 and the second insertion strip 38 are respectively punched with a first abutment piece 39 and a second abutment piece 40 for abutting against the inner sidewall of the transverse hole 36. The first abutment piece 39 and the second abutment piece 40 are respectively raised in the bending direction of the first insertion strip 37 and the second insertion strip 38. When the vertical beam 30 and the two transverse beams 31 are installed in the fish-eye hole 29, a vertical gap 41 is formed between the vertical beam 30 and the corresponding vertical hole 35.

[0024] Adding vertical beams and spaced horizontal beams inside the fisheye hole of the fisheye section enhances the overall structural strength and radial support of the fisheye section, preventing excessive shrinkage and deformation during press fitting. Multiple horizontal and vertical beams work together to divide the interior of the fisheye hole into a composite elastic beam structure, replacing the traditional single-span thin-walled elastic structure, resulting in more controllable and uniform elastic deformation. The vertical beams create a first and second set of elastic folded beams with opposite angles, and the two sets of horizontal beams are arranged in a bidirectional, staggered pattern, enabling multi-directional coordinated elastic deformation. This improves the clamping force between the fisheye section and the PCB socket, adapts to dimensional deviation compensation under wide-temperature thermal cycling, and disperses press fitting stress and long-term vibration loads, avoiding localized stress concentration and delaying structural fatigue. Meanwhile, the elastic beam structure with reverse bends has bidirectional elastic buffering capability, which can buffer vibration and impact in all directions, continuously maintain the tight fit between the fisheye section and the inner wall of the socket, stabilize the contact resistance, avoid loosening and poor connection problems, and greatly improve the durability and reliability of the terminal press-fit connection, making it suitable for the complex and harsh long-term operating conditions of IGBT modules. Meanwhile, the vertical and horizontal beams are installed in the fisheye holes using a plug-in connection. Due to the small internal space of the fisheye holes, a split structure facilitates production and assembly. However, the vertical and horizontal beams are integrally molded for simultaneous assembly and mutual constraint. When both the vertical and horizontal beams are installed in the fisheye holes, the vertical gap provides space for the plug-in connection at both ends of the vertical beam. Even if the fisheye segment is stretched due to lateral contraction when inserted into the PCB socket, the two ends of the vertical beam will not detach from their corresponding vertical holes, ensuring a stable connection. During removal, the vertical beam is pushed into the vertical hole at one end only, allowing one end to detach first before pulling out the other end. The ends of the horizontal beam are processed using metal cutting and bending techniques to create the first and second plug-in strips. The first plug-in strip... The first and second connectors bend in opposite directions and their ends approach each other. When the fisheye section is inserted into the PCB socket, the fisheye section contracts laterally. The ends of the two connectors abut against the inner bottom wall of the transverse hole and are further bent and deformed under force. This causes the abutting piece on the corresponding connector to abut against the inner wall of the transverse hole. The abutting piece is formed by punching and bending. Under the friction between the abutting piece and the inner wall of the transverse hole, the inner wall will be rubbed with a serrated pit. After the abutting piece is embedded in the pit, it will further lift up to form a more solid locking structure, ensuring the stable connection of the transverse beam installed on the fisheye section. At the same time, when the fisheye section is inserted into the PCB socket, the transverse beam is pressed and locked more tightly. When the transverse connector is not squeezed by the fisheye section, it will deform and reset to relax the abutting piece. If you want to remove it, you can easily pull the two transverse connectors out of the transverse hole by relying on the elastic deformation ability of the transverse beam's bend.

[0025] The mounting bracket is used for welding to the DBC ceramic substrate in the IGBT module. DBC (Direct Bonded Copper) is a direct copper-clad ceramic substrate.

[0026] When the first elastic flap and the second elastic flap are arranged in parallel, the first elastic flap and the second elastic flap are simultaneously connected between the fisheye segment and the second elastic segment.

[0027] This invention can be widely applied to IGBT power modules in fields such as new energy vehicle motor controllers, industrial frequency converters, photovoltaic inverters, and rail transit traction converters. It is especially suitable for high-end equipment scenarios with stringent requirements for connection reliability, vibration resistance, and high-temperature cycling resistance, providing core connection assurance for the stable operation of IGBT modules.

[0028] Further, the first elastic flap 6 is provided with at least one first crease 10, and the second elastic flap 7 is provided with at least one second crease 11. The bending directions of the first elastic flap 6 and the second elastic flap 7 are the same or opposite. When the bending directions of the first elastic flap 6 and the second elastic flap 7 are opposite, a lateral deformation range 12 is formed between the first crease 10 and the second crease 11.

[0029] The beneficial effects of this design are as follows: By setting at least one corresponding crease on the first and second elastic flaps respectively, a precise deformation guide path can be preset for the elastic flaps, constraining the deformation direction and stroke, dispersing bending stress, delaying elastic fatigue of the terminal material, and avoiding deformation instability; when the two elastic flaps bend in the same direction, the elastic deformation stroke of the two flaps can be superimposed, further improving the axial elastic compensation capability of the first elastic segment, strengthening the adaptability to the axial displacement and vibration impact of the IGBT module due to thermal expansion and contraction, and stabilizing the insertion contact pressure; when the two elastic flaps bend in opposite directions, a lateral deformation range is formed between the first crease and the second crease, ensuring that the fisheye terminal remains coaxial after the elastic deformation of the first elastic segment, comprehensively improving the contact stability of the terminal under complex working conditions, further reducing the risk of connection failure, and further ensuring the connection reliability between the IGBT module and the PCB board.

[0030] Furthermore, the first elastic segment 3 also includes a support column 13 disposed between the first elastic flap 6 and the second elastic flap 7. One end of the support column 13 is fixedly connected to the fisheye segment 2, and the other end is provided with a gap 14 between it and the second elastic segment 4.

[0031] The beneficial effects of this design are as follows: the support column enhances the structural rigidity of the first elastic segment, effectively constrains the deformation synchronization of the double elastic flaps, avoids uneven deformation and deformation instability on one side during insertion assembly and operating vibration, ensures uniform contact between the fisheye segment and the PCB board socket to stabilize contact resistance, and disperses the bending stress of the elastic flaps under high-frequency vibration and repeated thermal cycling conditions, avoiding stress concentration, further delaying material elastic fatigue, and extending the service life of the terminals. At the same time, the reserved gap not only fully preserves the original elastic deformation stroke and thermal deformation compensation capability of the double elastic structure, but also forms a rigid limit when the terminals are subjected to strong impact and large deformation, preventing excessive bending of the elastic flaps and plastic failure, greatly improving the impact and vibration resistance of the terminals, and further enhancing the connection reliability of the IGBT module under complex operating conditions.

[0032] Furthermore, gaps 15 are provided between the support column 13 and the first elastic flap 6, as well as between the support column 13 and the second elastic flap 7.

[0033] The beneficial effects of this design are as follows: the gap provides independent deformation space for the two elastic flaps, avoiding interference and limitation on the deformation stroke of the elastic flaps by the support column, fully preserving the axial and lateral elastic compensation capabilities of the two elastic flaps, and ensuring the terminal's adaptability to the thermal expansion and contraction and vibration of the IGBT module; it also avoids rigid friction and structural jamming between the elastic flaps and the support column during repeated deformation, effectively dispersing bending stress, reducing material wear and stress concentration, further delaying the elastic fatigue of the terminal under frequent thermal cycling and high-frequency vibration conditions, and extending its service life; at the same time, it ensures the synchronicity and consistency of the deformation of the two elastic flaps, avoiding uneven deformation on one side leading to off-center contact between the fisheye section and the PCB board hole, and maintaining uniform and stable contact pressure and contact resistance.

[0034] Further, the second elastic segment 4 includes two parallel first curved pieces 8, which are simultaneously connected between the first elastic segment 3 and the second curved piece 9, and a gap 16 is formed between the two first curved pieces 8. The second curved piece 9 is connected at a position relative to the gap 16.

[0035] The beneficial effects of this design are as follows: the symmetrical double-plate structure can effectively disperse the bending stress of the second elastic segment under repeated deformation, high-frequency vibration, and wide-temperature thermal cycling conditions, avoiding the stress concentration problem that is prone to occur in single-arm structures, delaying material elastic fatigue, and extending the service life of the terminals; the gap between the two plates provides sufficient deformation space for the bending plates, significantly improving the deformation redundancy and elastic compensation capability of the second elastic segment, forming a synergistic two-level elastic compensation effect with the first elastic segment, further enhancing the adaptability to the thermal expansion and contraction differences of the IGBT module, and stabilizing the insertion contact pressure and contact resistance; at the same time, the connection design of the gap corresponding to the second bending plate can ensure the synchronous deformation and uniform force of the two first bending plates, avoiding the problem of unilateral deformation and instability under assembly and operating conditions, improving the vibration and impact resistance of the terminals, and further reducing the risk of connection failure.

[0036] The two first bending plates can be bent in the same or opposite directions.

[0037] Furthermore, the bending directions of the first bent piece 8 and the second bent piece 9 are opposite.

[0038] The beneficial effects of this design are as follows: it constructs a bidirectional bending elastic energy storage structure, which significantly improves the elastic deformation stroke and deformation recovery force of the second elastic segment. At the same time, the reverse bending structure can disperse the bending stress to two reverse bending areas, avoiding the material plastic deformation and elastic fatigue problems caused by stress concentration at a single point.

[0039] Further, the needle 1 has guide slopes 17 on all four sides, and the fisheye segment 2 includes a straight segment 27 in the middle. The straight segment 27 is horizontal on all four sides, and the left and right sides of the straight segment 27 are provided with at least two chamfers 28 respectively.

[0040] The beneficial effects of this design are as follows: it facilitates precise and low-resistance press-fitting into PCB board holes, avoids jamming and scratching damage between the pin and the hole, and improves the efficiency and yield of solderless press-fitting assembly. The straight section of the fisheye segment ensures linear contact between the fisheye terminal and the PCB board hole. Combined with at least two chamfers on both sides, the multi-level segmented chamfers can use different radii to form multiple arcs. Even after PCB board deformation, it can maximize the contact area between the fisheye terminal and the PCB board hole, ensuring uniform and stable contact, effectively reducing contact resistance. The chamfers also act as a progressive guide, reducing the insertion resistance during straight-segment press-fitting, improving assembly smoothness and press-fitting accuracy. At the same time, it can disperse local stress under insertion, removal, and long-term vibration conditions, reducing wear and plastic deformation of the straight segment and maintaining a stable long-term insertion clamping force.

[0041] Further configuration involves the second curved piece 9 being snapped into connection with the fixed base 5.

[0042] The benefits of this design are as follows: it facilitates and secures assembly, strengthens the core advantage of the fisheye terminal's solderless assembly, significantly improves assembly and disassembly efficiency, and facilitates later maintenance.

[0043] Further, it also includes a connecting section 18 connecting the first elastic segment 3 and the second elastic segment 4, with a positioning boss 19 on each side of the connecting section 18.

[0044] The beneficial effects of this design are as follows: A smooth transition between the two-stage elastic structure is achieved through the connecting segment, ensuring the synchronized deformation of the first and second elastic segments, avoiding stress concentration and deformation instability caused by misalignment of the two elastic bodies, dispersing bending stress at the connection point, and delaying elastic fatigue of the terminal material. Sometimes, depending on product requirements, the connecting segment, the second elastic segment, and the mounting base are integrated with the IGBT module using injection molding. In this case, the second elastic segment loses its elastic deformation capability, but the first elastic segment still retains the elastic deformation compensation capability of the fisheye terminal, ensuring a stable electrical connection. Alternatively, only the connecting segment and the IGBT module are encapsulated. Although the second elastic segment and the mounting base are also installed inside the IGBT module, they are not completely rigid, and the second elastic segment can still provide elastic deformation compensation, making it suitable for more working scenarios.

[0045] A manufacturing process for a double-elastic fisheye terminal for an IGBT module includes the following steps: S1: The strip is fed into the progressive die for the first punching process, punching out the two-dimensional outer contour of the fisheye terminal. Fisheye holes are punched out in the fisheye section 2. Parallel first elastic flaps 6, support pillars 13, and second elastic flaps 7 are punched out in the first elastic section 3. Scrap is punched out on both sides of the support pillar 13 and at one end near the connecting section 18 to form gaps 15 and 14. A positioning boss 19 is punched out in the connecting section 18. Two first bent pieces 8 and a second bent piece 9 are punched out in the second elastic section 4. Scrap is punched out between the two first bent pieces 8 to form a gap 16. Simultaneously, the outer contour of the fixing seat 5 is punched out. The raw material used is copper alloy strip with high yield strength and excellent conductivity (such as C7025 titanium copper or C5191 phosphor bronze), with a strip thickness of 0.6mm~0.8mm. The entire manufacturing process relies on a high-speed punch press (punching tonnage 40T-60T) and high-precision progressive dies. At the punching and blanking station, the planar unfolded outline of the terminal is punched out. The width of the first and second elastic flaps within the first elastic section is controlled between 0.3mm and 0.5mm; the gap between the support column and the connecting section is precisely controlled between 0.1mm and 0.15mm, serving as a buffer allowance for subsequent pressure; the slit width is controlled at 0.1mm to ensure the service life of the punching tool and the structural independence of the terminal.

[0046] S2: The conveyor belt undergoes a second extrusion molding process, extruding guide slopes 17 around the sides of the needle 1, extruding chamfers 28 on both sides of the straight section 27, and simultaneously extruding several raised solder points 26 on the fixed seat 5; the upper and lower molds close to extrude a 45° chamfer around the sides of the needle to form smooth guide slopes; the outer edge of the straight section of the fisheye segment is crushed to form an arc chamfer of R0.05~R0.1; at the same time, through the forming punch below the fixed seat, solder points with a height of 0.1mm~0.2mm are extruded upwards to form solder points for subsequent SMT placement or laser welding.

[0047] S3: Continue conveying the conveyor belt for the third three-dimensional bending and forming process. Press creases with opposite bending directions on the first elastic fold 6 and the second elastic fold 7 respectively. Bend the first bending piece 8 and the second bending piece 9 in the opposite direction to form an S-shaped structure. At the same time, bend the fixing seat 5 to be relatively perpendicular to the connecting section 18, and the welding point 26 is located on the side of the fixing seat 5 away from the second elastic section 4. Use the forming punch to apply lateral pressure to the two elastic folds of the first elastic section, so that they bend in opposite directions with a bending angle of 10°~15° to form a rhomboid or elliptical elastic expansion zone. Subsequently, continuously bend the second elastic section in the Z-axis direction. Both the first bending piece and the second bending piece are bent into a U-shape or semi-circle (the inner bending radius R ≥ thickness T to prevent micro-cracks), forming an "S"-shaped shock-absorbing structure with axial tensile and compressive capabilities.

[0048] S4: Electroplating process. The one-piece stamped fisheye terminal strip is fed into the electroplating line for overall or partial tin or gold plating. The continuous stamped strip is transferred to the continuous electroplating line via a take-up tray. First, full-bottom nickel plating (thickness 1.27μm~2.54μm) is performed to prevent copper ion migration. Then, partial tin or gold plating (gold layer thickness 0.3μm~0.76μm) is performed on the fisheye section and needle area to reduce the insertion and extraction friction coefficient and improve oxidation resistance.

[0049] S5: Perform the cutting and separation process, and make the fisheye terminal form an independent unit by cutting the connecting ribs at the edge of the strip; S6: Conduct pressure stability and long-term vibration condition tests, and measure the ultimate deformation resistance of the fisheye terminal and the wear condition of the outer surface of the fisheye section.

[0050] The pressure stability test involves extracting a sample, clamping it to a material testing machine, applying axial pressure to the needle in a simulated insert-plate environment, and recording the deformation curve in real time using a force-displacement sensor until plastic yielding occurs in the first or second elastic segment. The ultimate resistance to deformation is then measured and calculated. Mechanical test data shows: under 100N pressure, the deformation is 0.41~0.56mm with no permanent deformation; the ultimate resistance to deformation reaches a maximum of 197.64N, far exceeding conventional load conditions, providing sufficient safety redundancy; after 1000 thermal cycles at -40℃ to 150℃, the elasticity retention rate is ≥95%. Under a standard load of 20N, the terminal exhibits stable elasticity and effective deformation, meeting the requirements for press-fitting and long-term vibration conditions.

[0051] The long-term vibration test and wear measurement involved pressing the sample into the electroplated through-hole of a standard PCB board and placing it on a high-frequency vibration test bench to simulate the actual working environment for triaxial high-frequency vibration testing. After the test, the terminals were removed, and a three-dimensional profilometer was used to scan the straight sections and chamfered areas on the outer surface of the fisheye section to measure its wear depth and wear volume. The test results showed that under vibration conditions of 10~2000Hz and 10g acceleration, the fretting wear on the fisheye contact surface was reduced by more than 85%, and the contact resistance fluctuation was ≤5%.

[0052] Steps S5 and S6 can be interchanged, or the material strip can be sampled first and then fed into the cutting machine to cut off the edge material of the carrier strip, so that the fixing seat and the connecting rib are separated. Finally, the carrier strip is used for automated winding, sealed and put into storage.

[0053] The overall structure is formed by one-piece stamping using progressive dies, resulting in a fast production cycle and high material utilization. Combined with rigorous pressure and vibration wear quantification testing procedures, the long service life of the product is guaranteed from the source of the process in harsh environments such as automotive electronics.

[0054] like Figures 6 to 7 As shown, in a second embodiment of the present invention, the second elastic segment 4 includes a first S-shaped bending piece 20 and two first support pieces 21. The two first support pieces 21 are symmetrically distributed on both sides of the first S-shaped bending piece 20. The first S-shaped bending piece 20 is connected between the first elastic segment 3 and the fixed seat 5. One end of each of the two first support pieces 21 is fixedly connected to the first elastic segment 3, and the other end of each of the two first support pieces 21 is provided with a first buffer space 22 between it and the fixed seat 5. A plurality of welding points 26 are provided on the bottom surface of the fixed seat 5.

[0055] The beneficial effects of this design are as follows: the first S-shaped bending piece directly possesses multi-level bending deformation capability, with a larger deformation stroke and stronger elastic buffering effect; the symmetrical first support pieces on both sides can effectively improve the overall structural strength and lateral stiffness of the second elastic segment, suppress lateral sway and deformation skew of the terminals, avoid uneven load distribution, and at the same time disperse structural stress and delay material elastic fatigue; the first buffer zone reserves an independent deformation buffer space for the first support piece, enabling the second elastic segment to also have rigid limiting, working in conjunction with the first S-shaped bending piece to achieve flexible buffering, balancing structural support and elastic deformation capability, adapting to complex and harsh operating environments; the several protruding solder points at the bottom of the fixing base can achieve... The mounting bracket is securely welded to the DBC ceramic substrate in the IGBT module. Combined with the overall dual-elastic structure of the terminals, it combines the advantages of solderless press-fit connection with the reinforcement effect of bottom welding, effectively improving the installation firmness of the mounting bracket and resisting the risk of loosening caused by high-frequency vibration and temperature shock. The multiple solder joints distribute the stress evenly, which can disperse the welding stress and operating load, prevent local desoldering and cracking, avoid failure of the fixing part, and improve the overall installation positioning accuracy of the terminals, limit the offset and wobbling of the mounting bracket, ensure the overall structural stress balance, and continuously maintain the stable contact state between the fisheye terminals and the PCB board. This further reduces the probability of connection failure under long-term complex operating conditions and comprehensively improves the connection reliability and service life of the IGBT module.

[0056] like Figure 8 As shown, in the third embodiment of the present invention, the second elastic segment 4 includes a second support piece 23 and two second S-shaped bending pieces 24. The two second S-shaped bending pieces 24 are symmetrically distributed on both sides of the second support piece 23, and the two second S-shaped bending pieces 24 are connected and disposed between the first elastic segment 3 and the fixed seat 5. One end of the second support piece 23 is fixedly connected to the first elastic segment 3, and a second buffer space 25 is provided between the other end and the fixed seat 5. A plurality of welding points 26 are provided on the bottom surface of the fixed seat 5.

[0057] The beneficial effects of this design are as follows: the second support plate, located in the middle, strengthens the overall support rigidity of the second elastic segment, ensuring coaxiality and contact uniformity of the insertion, continuously stabilizing the contact pressure between the fisheye segment and the PCB socket, suppressing the increase in contact resistance, and further improving the connection stability and service life of the IGBT module and the PCB board under harsh operating conditions. The second buffer zone also provides rigid limiting. The two S-shaped bending plates on both sides deform in tandem, resulting in a larger elastic buffer stroke and a wider deformation compensation range. This effectively adapts to the thermal expansion and contraction deformation of the IGBT module under wide temperature thermal cycling, effectively buffering high-frequency vibration and alternating impact. At the same time, the two S-shaped bending plates are evenly stressed, which can disperse bending stress and improve the fatigue resistance of the structure. The solder joints at the bottom of the fixing base also have the advantage of making the welding more robust.

[0058] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A double-elastic fisheye terminal for an IGBT module, characterized in that: The device includes a needle (1), a fisheye segment (2), a first elastic segment (3), a second elastic segment (4), and a fixing seat (5) connected in sequence. The needle (1) is used to insert into the PCB board. The fisheye segment (2) is used to connect with the socket of the PCB board. The first elastic segment (3) includes a first elastic flap (6) and a second elastic flap (7) arranged in parallel or connected in sequence. The second elastic segment (4) includes a first curved piece (8) and a second curved piece (9) connected in sequence. The end of the first curved piece (8) away from the second curved piece (9) is connected to the first elastic segment (3). The end of the second curved piece (9) away from the first curved piece (8) is connected to the fixing seat (5). The fixing seat (5) is used to connect with the IGBT module. The fisheye segment (2) has a fisheye hole (29) extending through its side. The fisheye hole (29) contains at least one vertical beam (30) and at least two horizontal beams (31). The vertical beam (30) is coaxial with the fisheye segment (2). The two horizontal beams (31) are spaced apart on the vertical beam (30). The vertical beam (30) divides the horizontal beam (31) into a first elastic folded beam (32) and a second elastic folded beam (33). Both the first elastic folded beam (32) and the second elastic folded beam (33) have bends (34), and the bends (34) of the first elastic folded beam (32) and the second elastic folded beam (33) are in opposite directions. The bends (34) of the two horizontal beams (31) are in opposite directions. The inner wall of the fisheye hole (29) also has at least two vertical holes (35) for the two ends of the vertical beam (30) to be inserted into. There are four horizontal holes (36). Each of the horizontal beams (31) has a first insert strip (37) and a second insert strip (38) at both ends, which are cut and bent to fit into the horizontal holes (36). The bending directions of the first insert strip (37) and the second insert strip (38) are opposite and their ends are close to each other. The first insert strip (37) and the second insert strip (38) are punched with a first abutting piece (39) and a second abutting piece (40) for abutting against the inner wall of the horizontal hole (36). The first abutting piece (39) and the second abutting piece (40) are respectively raised in the bending direction of the first insert strip (37) and the second insert strip (38). When the vertical beam (30) and the two horizontal beams (31) are installed in the fish-eye hole (29), a vertical gap (41) is formed between the vertical beam (30) and the corresponding vertical hole (35).

2. The double elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The first elastic flap (6) has at least one first crease (10), and the second elastic flap (7) has at least one second crease (11). The bending directions of the first elastic flap (6) and the second elastic flap (7) are the same or opposite. When the bending directions of the first elastic flap (6) and the second elastic flap (7) are opposite, a transverse deformation zone (12) is formed between the first crease (10) and the second crease (11).

3. A double-elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The first elastic segment (3) also includes a support column (13) disposed between the first elastic flap (6) and the second elastic flap (7). One end of the support column (13) is fixedly connected to the fisheye segment (2), and the other end is provided with a gap (14) between it and the second elastic segment (4).

4. A double-elastic fisheye terminal for an IGBT module according to claim 3, characterized in that: There are gaps (15) between the support column (13) and the first elastic flap (6) and between the support column (13) and the second elastic flap (7).

5. A double-elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The second elastic segment (4) includes two parallel first curved pieces (8), which are connected between the first elastic segment (3) and the second curved piece (9) at the same time, and a gap (16) is formed between the two first curved pieces (8), and the second curved piece (9) is connected at the position of the gap (16).

6. A double-elastic fisheye terminal for an IGBT module according to claim 5, characterized in that: The bending direction of the first bent piece (8) is opposite to that of the second bent piece (9).

7. A double-elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The needle (1) has guide slopes (17) on all four sides. The fisheye segment (2) includes a straight segment (27) in the middle. The straight segment (27) is horizontal on all four sides, and the left and right sides of the straight segment (27) are provided with at least two chamfers (28). It also includes a connecting section (18) connecting the first elastic segment (3) and the second elastic segment (4), and a positioning boss (19) is provided on both sides of the connecting section (18).

8. A double-elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The second elastic segment (4) includes a first S-shaped bending piece (20) and two first support pieces (21). The two first support pieces (21) are symmetrically distributed on both sides of the first S-shaped bending piece (20). The first S-shaped bending piece (20) is connected between the first elastic segment (3) and the fixed seat (5). One end of each of the two first support pieces (21) is fixedly connected to the first elastic segment (3), and the other end of each of the two first support pieces (21) is provided with a first buffer space (22) between it and the fixed seat (5). Several welding points (26) are provided on the bottom surface of the fixed seat (5).

9. A double-elastic fisheye terminal for an IGBT module according to claim 1, characterized in that: The second elastic segment (4) includes a second support piece (23) and two second S-shaped bending pieces (24). The two second S-shaped bending pieces (24) are symmetrically distributed on both sides of the second support piece (23), and the two second S-shaped bending pieces (24) are connected and disposed between the first elastic segment (3) and the fixed seat (5). One end of the second support piece (23) is fixedly connected to the first elastic segment (3), and a second buffer zone (25) is provided between the other end and the fixed seat (5). Several welding points (26) are provided on the bottom surface of the fixed seat (5).

10. A manufacturing process for a double-elastic fisheye terminal for an IGBT module according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Feed the strip into the continuous die and perform the first punching process to punch out the two-dimensional outer contour unfolded view of the fisheye terminal. Punch out the fisheye hole in the fisheye section (2). Punch out the first elastic fold (6), support column (13) and second elastic fold (7) in parallel distribution in the first elastic section (3). Punch out the waste material on both sides of the support column (13) and at one end near the connecting section (18) to form a gap (15) and a gap (14). Punch out the positioning boss (19) in the connecting section (18). Punch out two first curved pieces (8) and a second curved piece (9) in the second elastic section (4). Punch out the waste material between the two first curved pieces (8) to form a gap (16). At the same time, punch out the outer contour of the fixing seat (5). S2: The conveyor belt undergoes a second extrusion molding process, extruding guide slopes (17) around the needle (1), extruding chamfers (28) on both sides of the straight section (27), and extruding several raised welding points (26) on the fixed seat (5). S3: Continue conveying the material belt to carry out the third three-dimensional bending forming process. Press creases with opposite bending directions on the first elastic fold (6) and the second elastic fold (7) respectively. Bend the first bending piece (8) and the second bending piece (9) in the opposite direction to form an S-shaped structure. At the same time, bend the fixed seat (5) to be relatively perpendicular to the connecting section (18), and the welding point (26) is located on the side of the fixed seat (5) away from the second elastic section (4). S4: Perform the electroplating process, feeding the one-piece stamped fisheye terminal strip into the electroplating line for overall or partial tin plating or gold plating. S5: Perform the cutting and separation process, and make the fisheye terminal form an independent unit by cutting the connecting ribs at the edge of the strip; S6: Conduct pressure stability and long-term vibration condition tests, and measure the ultimate deformation resistance of the fisheye terminal and the wear condition of the outer surface of the fisheye section.

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