Heterogeneous welded copper busbar with directional flow guidance function

Abstract

The present invention discloses a dissimilar welding copper busbar with a directional flow-guiding function, comprising copper busbars, including an upper copper busbar and a lower copper busbar; and a silver sheet positioned between the upper and lower copper busbars. The copper busbar has a central positioning groove for accommodating the silver sheet, with flow-guiding channels connecting the two sides of the central positioning groove. Mechanical stops are connected to the ends of the flow-guiding channels facing away from the central positioning groove. The mechanical stops are located on both sides of the copper busbar and include inclined guide surfaces formed by chamfers on both sides of the lower copper busbar. This invention eliminates cold solder joints and controls flashing through a flow-guiding and limiting structure, thereby controlling the maximum width of the silver sheet after melting and cooling, thereby facilitating subsequent secondary processing.

Description

Technical Field

[0001] The invention relates to the technical field of power components and welding thereof, and in particular to a heterogeneous welded copper busbar with directional flow guiding function. Background Art

[0002] Copper busbars are long conductors used for conducting high currents. Their core applications include high and low voltage electrical equipment, power distribution equipment, bus ducts, and other electrical engineering projects.

[0003] In the power and electronics fields, silver sheeting has become the preferred material for critical connections due to its extremely low contact resistance and excellent oxidation resistance. Welding a copper busbar to silver sheeting ensures low cost for the main conductive components while achieving a performance boost at the critical nodes of current transmission.

[0004] For welding copper busbars to silver sheets, existing welding technologies include pulsed arc welding (PSA), an advanced gas shielded arc welding process that achieves low heat input, low spatter, stable droplet transfer, and excellent weld quality by precisely controlling the current and voltage to periodically switch between high and low values. It has advantages in welding thin plates, heat-sensitive materials, and all-position welding. Copper busbar resistance welding utilizes the resistance heat generated by current passing through the contact surface, while simultaneously applying pressure to achieve a secure connection between copper busbars or between copper busbars and other conductors. It is particularly suitable for manufacturing high-current connectors requiring high conductivity and mechanical strength.

[0005] When welding copper busbars and silver sheets, current flows through the polymer material or a conductive medium (such as metal foil or conductive fiber) placed between the polymer materials. This heat locally heats the polymer material to a molten or softened state, while simultaneously applying pressure to promote interfacial fusion, forming a strong connection after cooling. This can easily lead to solder overflow after welding, exceeding the width of the copper busbar, or the risk of cold solder joints, which can lead to secondary processing issues.

[0006] Figure 2 A heterogeneous copper busbar structure is shown, which is a composite layer including, from top to bottom, an upper copper busbar 4, a silver sheet 6, and a lower copper busbar 5.

[0007] Figure 3 、 Figure 4 The lower copper bar 5 is shown. The upper surface of the lower copper bar 5 is provided with a rectangular pit-shaped limiting groove 501 for accommodating the silver sheet 6.

[0008] Figure 5 、 Figure 6 A defect is shown, that is, the silver sheet 6 overflows from the edge after welding, forming an overflow defect 601, forming a width greater than the entire copper busbar, affecting subsequent secondary processing and assembly.

[0009] Figure 7 、 Figure 8Another defect is shown, that is, the silver sheet 6 after welding does not overflow from the edge and does not form a width greater than the entire copper busbar, but constitutes a cold soldering defect 602. Summary of the Invention

[0010] The problem to be solved by the present invention is to provide a heterogeneous welded copper busbar with directional flow conduction function.

[0011] To solve the above problems, the present invention provides a heterogeneous welded copper busbar with directional flow guidance function. To achieve the above objectives, the technical solution adopted by the present invention to solve the technical problems is:

[0012] A dissimilar welding copper busbar with a directional guide function comprises: copper buses, including an upper copper busbar and a lower copper busbar; a silver sheet located between the upper and lower copper buses; wherein the copper busbar has a central positioning groove for accommodating the silver sheet, and diversion channels are connected on both sides of the central positioning groove, and a mechanical stop is connected to one end of the diversion channel facing away from the central positioning groove; the mechanical stop is located on both side edges of the copper busbar, and the mechanical stop comprises an inclined guide surface formed by chamfering on both side edges of the lower copper busbar.

[0013] As a further improvement of the present invention, the horizontal cross-sectional profile of the central positioning groove is a rectangle. When the silver sheet is placed in the central positioning groove, there is a gap between the edge of the unmelted silver sheet and the central positioning groove.

[0014] As a further improvement of the present invention, the two guide channels are symmetrically distributed on both sides of the central positioning groove, and the width of the guide channel is smaller than the length of any side of the central positioning groove.

[0015] As a further improvement of the present invention, the guide channel is a gradually expanding guide channel. The width of the gradually expanding guide channel gradually widens from the central positioning groove to the mechanical stop portion, and the depth of the gradually expanding guide channel is constant and equal to the depth of the central positioning groove.

[0016] As a further improvement of the present invention, the width of the mechanical stop portion is greater than the width of the guide channel and also greater than the width of the central positioning groove.

[0017] As a further improvement of the present invention, the inclined guide surface is chamfered at 45 degrees, and the inclined guide surface forms convex ridge lines on both side elevations of the upper copper busbar.

[0018] As a further improvement of the present invention, the molten silver sheet contacts the inclined guide surface of the lower copper bar and flows obliquely downward, thereby forming a drooping overflow bag.

[0019] As a further improvement of the present invention, the mechanical stop portion also includes a stepped width difference formed by the different widths of the upper copper bar and the lower copper bar, the width of the lower copper bar is greater than the width of the upper copper bar, and the two sides of the lower copper bar are more convex than the two sides of the upper copper bar; the silver sheet in the molten state is infiltrated into the two side facades of the upper copper bar and flows upward, thereby forming an upward extension overflow package.

[0020] As a further improvement of the present invention, the roughness Ra of the vertical surfaces on both sides of the upper copper busbar ranges from 0.8 μm to 3.2 μm.

[0021] As a further improvement of the present invention, the hardness of the lower copper busbar is greater than the hardness of the upper copper busbar.

[0022] The beneficial effects of using the dissimilar welded copper busbar with directional flow guidance function of the present application are:

[0023] A central positioning groove for accommodating the silver sheet is set on the lower copper bar, and diversion channels are connected on both sides of it, and finally a mechanical stop part with an inclined guide surface is formed on the edge of the copper bar, which effectively solves the key problem in dissimilar welding.

[0024] Under pressure, the molten silver is guided into the flow channel and flows diagonally downward along the inclined guide surface. This structure ensures sufficient filling and effective spread of the silver at the soldering interface, significantly reducing the risk of cold solder joints. Furthermore, the mechanical stop acts as a physical barrier, precisely constraining the flow boundary of the molten silver, forming a controlled sagging overflow pocket and preventing disordered lateral diffusion of the silver. This ensures that the overall width of the copper busbar after soldering does not exceed the original size, directly meeting subsequent assembly requirements.

[0025] This integrated design of grooves, channels, and stops, which combine positioning, flow guidance, and position limiting, allows for precise control of the direction and range of molten silver flow during the welding process. This improves the quality and reliability of the weld interface and, more importantly, completely eliminates the need for post-weld secondary processing due to silver overflow, resulting in product width exceeding specifications or cold weld defects. This simplifies the process, improves production efficiency, and increases product qualification rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is a structural diagram of the copper bar resistor welding assembly;

[0028] Figure 2It is a structural diagram of the welding product;

[0029] Figure 3 This is a top view of the lower copper busbar;

[0030] Figure 4 This is the left view of the lower copper bar;

[0031] Figure 5 This is the first defect effect diagram of the copper bar resistor welding assembly;

[0032] Figure 6 yes Figure 5 A local enlarged view of point A;

[0033] Figure 7 This is the second defect effect diagram of the copper bar resistor welding assembly;

[0034] Figure 8 yes Figure 7 A partial enlarged view of point B;

[0035] Figure 9 1 is a top view of an embodiment of the lower copper busbar of the present invention;

[0036] Figure 10 This is a left side view of an embodiment of the lower copper busbar of the present invention;

[0037] Figure 11 It is a rendering of the first embodiment of the present invention;

[0038] Figure 12 yes Figure 11 A partial enlarged view of point C;

[0039] Figure 13 It is a rendering of a second embodiment of the present invention;

[0040] Figure 14 yes Figure 13 A partial enlarged view of point D;

[0041] Figure 15 It is a partial effect diagram of the third embodiment of the present invention.

[0042] 1-upper electrode; 2-lower electrode; 3-welding product; 4-upper copper busbar; 401-first roughness surface; 5-lower copper busbar; 501-limiting groove; 5011-central positioning groove; 5012-gradually expanding guide channel; 5013-mechanical stopper; 50131-inclined guide surface; 50132-stepped width difference; 502-convex ridge line; 503-second roughness surface; 6-silver sheet; 601-overflow package defect; 602-cold soldering defect; 603-drooping overflow package; 604-upward extension overflow package. DETAILED DESCRIPTION

[0043] The present invention will be described in further detail below with reference to specific embodiments:

[0044] In order to achieve the purpose of the present invention, a dissimilar welding copper bar with directional guide function includes: a copper bar, including an upper copper bar 4 and a lower copper bar 5; a silver sheet 6, located between the upper copper bar 4 and the lower copper bar 5; wherein the copper bar has a central positioning groove 5011 for accommodating the silver sheet 6, and the two sides of the central positioning groove 5011 are connected to the guide channel, and the end of the guide channel away from the central positioning groove 5011 is connected to the mechanical stop portion 5013; the mechanical stop portion 5013 is located at the two side edges of the copper bar, such as Figure 11 、 Figure 12 The mechanical stop portion 5013 includes an inclined guide surface 50131 formed by chamfers on both sides of the lower copper busbar 5 .

[0045] In addition, the silver sheet 6 is an alloy containing silver, and the upper copper bar 4 and the lower copper bar 5 are an alloy containing copper.

[0046] The beneficial effect of the above technical solution is that the central positioning groove 5011 adopts a rectangular profile and maintains an assembly clearance with the silver sheet 6. This design allows the silver sheet 6 to expand freely within the groove when heated, avoiding local stress concentration or deviation from the silver material extrusion path due to thermal expansion. The rectangular structure also facilitates machining and molding, improving the groove's dimensional accuracy and consistency.

[0047] In other embodiments of the present invention, the horizontal cross-sectional profile of the central positioning groove 5011 is rectangular. When the silver sheet 6 is placed in the central positioning groove 5011 , there is a gap between the edge of the unmelted silver sheet 6 and the central positioning groove 5011 .

[0048] like Figure 9 、 Figure 10 As shown, in some other embodiments of the present invention, the two guide channels are symmetrically distributed on both sides of the central positioning groove 5011 , and the width of the guide channel is smaller than the length of any side of the central positioning groove 5011 .

[0049] The beneficial effect of adopting the above technical solution is that the two guide channels are symmetrically distributed and their width is smaller than the length of any side of the central positioning groove 5011. This symmetrical layout ensures that the molten silver material flows evenly to both sides and avoids segregation.

[0050] like Figure 9 、 Figure 10 As shown, in some other embodiments of the present invention, the guide channel is a gradually expanding guide channel 5012, and the width of the gradually expanding guide channel 5012 gradually widens from the central positioning groove 5011 to the mechanical stop portion 5013, and the depth of the gradually expanding guide channel 5012 is constant and equal to the depth of the central positioning groove 5011.

[0051] In addition, the central positioning groove 5011 and the gradually expanding guide channel 5012 are both recessed in the upper surface of the lower copper busbar 5. The central positioning groove 5011 and the gradually expanding guide channel 5012 form a continuous limiting groove.

[0052] The beneficial effect of adopting the above technical solution is that the guide channel is designed as a gradually expanding guide channel 5012. The gradually expanding structure provides a path with decreasing flow resistance for the molten silver material, guiding it to accelerate and flow toward the mechanical stopper 5013. The depth is consistent with the central positioning groove 5011, which ensures that the cross-sectional pressure during the flow of the silver material is stable, avoiding turbulence or stagnation caused by sudden changes in depth. Figure 9 As shown, in some other embodiments of the present invention, the width of the mechanical stop portion 5013 is greater than the width of the guide channel and also greater than the width of the central positioning groove 5011.

[0053] The beneficial effect of adopting the above technical solution is that the width of the mechanical stopper 5013 is greater than the guide channel and the central positioning groove 5011. This width difference forms a protruding interception platform at the edge of the copper busbar, providing a sufficient collision buffer surface for the molten silver material, ensuring that the sagging overflow bag 603 is completely confined within the projected boundary of the lower copper busbar 5.

[0054] like Figure 12 As shown, in some other embodiments of the present invention, the inclined guide surface 50131 is chamfered at 45°, and the inclined guide surface 50131 forms convex ridges 502 on both side elevations of the upper copper busbar 4 .

[0055] The convex ridge line 502 is sharp enough to form a 135° positive angle ridge line.

[0056] The beneficial effect of the above technical solution is that the inclined guide surface 50131 adopts a 45° chamfer and forms a ridge line 502 on the upper copper busbar 4. The 45° angle optimizes the downward flow trajectory of the molten silver material, causing it to naturally droop along the tangential direction. The sharp edge of the ridge line 502 severs the adhesion of the silver material to the sidewall of the upper copper busbar 4, forcing the silver material to break away from the sidewall and drip downward.

[0057] like Figure 12 As shown, in some other embodiments of the present invention, the molten silver sheet 6 contacts the inclined guide surface 50131 of the lower copper bus 5 and flows obliquely downward, thereby forming a drooping overflow bag 603.

[0058] The beneficial effect of the above technical solution is that after the molten silver sheet 6 contacts the inclined guide surface 50131, it flows obliquely downward to form a drooping overflow bag 603. This is a direct manifestation of the function of the mechanical stopper 5013. Through directional guidance, the excess silver material is concentrated into a drooping shape, preventing lateral diffusion and excessive width.

[0059] like Figure 13 、 Figure 14 As shown, in other embodiments of the present invention, the mechanical stop portion 5013 further includes a stepped width difference 50132 formed by the different widths of the upper copper bar 4 and the lower copper bar 5, the width of the lower copper bar 5 is greater than the width of the upper copper bar 4, and the two sides of the lower copper bar 5 are more convex than the two sides of the upper copper bar 4; the silver sheet 6 in the molten state is infiltrated into the two side facades of the upper copper bar 4 and flows upward, thereby forming an upward extended overflow package 604.

[0060] The beneficial effect of the above technical solution is that the mechanical stop 5013 includes a stepped width difference 50132, that is, the lower copper bar 5 is wider than the upper copper bar 4, and the molten silver sheet 6 infiltrates the side wall of the upper copper bar 4 to form an upward overflow 604. The stepped difference creates a vertical silver material accommodating space, allowing the overflowing silver material to climb along the vertical surface of the upper copper bar 4 and wrap around its edge, preventing lateral overflow and enhancing the bonding strength of the end of the upper copper bar 4.

[0061] In some other embodiments of the present invention, the roughness Ra of the vertical surfaces on both sides of the upper copper busbar 4 ranges from 0.8 μm to 3.2 μm.

[0062] In addition, if Figure 14 As shown, the vertical surfaces on both sides of the upper copper busbar 4 are the first roughness surface 401, and the uncovered surface on the upper surface of the lower copper busbar 5 is the second roughness surface 503. The preferred range of the first roughness surface 401 is 0.8μm to 3.2μm. When the intrinsic contact angle θ of molten silver on the clean, non-oxidized smooth surface of pure copper is less than 90°, it is a good wetting system. Excessive roughness will make it difficult for the molten metal to completely fill deep grooves, and it is easy to encapsulate gas, which in turn reduces the effective contact area and bonding strength, and even introduces defects. If the roughness Ra range is less than 0.8μm, the bonding strength is generally low due to the lack of mechanical bite effect due to excessive mirroring. If the roughness Ra range is significantly greater than 3.2μm, it is difficult for molten silver to flow into deep and narrow grooves or large pores, and it is easy to encapsulate gas or flux residue, thereby forming defects.

[0063] The beneficial effect of the above technical solution is that the roughness Ra of the vertical surfaces of the upper copper busbar 4 on both sides is controlled to be between 0.8 μm and 3.2 μm. This range allows the surface micro-protrusions to pierce the molten silver oxide film to promote wetting, while also preventing the formation of deep grooves that trap gas or flux due to excessive roughness, ensuring that the upper extended overflow 604 forms a dense metallurgical bond with the copper busbar.

[0064] In addition, if Figure 15 As shown, the stepped width difference 50132 can be equal to the lateral width of the inclined guide surface 50131. The molten silver sheet 6 can form an upwardly extending overflowing bag 604 and a downwardly drooping overflowing bag 603 at the same time.

[0065] In some other embodiments of the present invention, the hardness of the lower copper busbar 5 is greater than the hardness of the upper copper busbar 4 .

[0066] In a preferred embodiment, the upper copper busbar 4 is made of tough pitch copper (Cu-ETP, C11000) with an annealed hardness of HV45-55, and the lower copper busbar 5 is made of chromium zirconium copper (CuCrZr, C18150) with a hardness of HV120-150.

[0067] The beneficial effect of adopting this technical solution is that the lower copper busbar 5 is harder than the upper copper busbar 4. The hard lower copper busbar 5 is less likely to deform under welding pressure, maintaining the geometric accuracy of the central positioning groove 5011 and the gradually expanding flow guide channel 5012. Meanwhile, the relatively soft upper copper busbar 4 is more easily plastically deformed to fit the silver sheet 6, increasing the interfacial contact area.

[0068] In one embodiment, an array of micron-sized copper-tungsten alloy bumps is added to the inclined guide surface 50131. The bumps have a diameter of 50 to 200 μm and a height of 20 to 80 μm, with a spacing of 1.5 to 2 times the diameter. The bumps are made of copper-tungsten alloy (CuW80). When the soldering temperature exceeds 400°C, the copper busbar's base thermally expands more than the bumps, causing them to sink relatively into the inclined guide surface 50131, forming a smooth transition surface. When cooled to below 200°C, the copper busbar contracts more than the bumps, causing the bumps to protrude from the surface, forming a physical gripping structure.

[0069] During the high-temperature soldering stage, the bumps sink into the surface of the inclined guide surface 50131. Crucially, this maintains the low resistance of the inclined guide surface 50131, ensuring that the molten silver material 6 flows smoothly to the predetermined location, forming a sagging overflow pocket 603. However, during the low-temperature solidification stage, the bumps protrude from the surface, mechanically gripping the semi-solidified silver material and suppressing shrinkage or cracking due to volumetric contraction, thereby increasing the density and interfacial bonding strength of the sagging overflow pocket 603. To a certain extent, this dynamically controls the smoothness and size of the sagging of the sagging overflow pocket 603.

[0070] Figure 1 The figure shows a processing diagram of a welding product 3 consisting of an upper copper busbar 4, a silver sheet 6, and a lower copper busbar 5 from top to bottom, with an upper electrode 1 and a lower electrode 2 provided above and below the busbar, respectively.

[0071] The composite flow guide system on the welding surface includes a central positioning groove 5011, whose width is adapted to the size of the silver sheet 6 while maintaining assembly clearance. Extending from the central positioning groove 5011 to the sides are gradually expanding flow guide channels 5012. Furthermore, inclined guide surfaces 50131 are provided on the sides of the copper busbars, with mechanical stops 5013 formed at the ends of the inclined guide surfaces 50131. The width of the soft copper busbar (upper copper busbar 4) or the hard copper busbar (lower copper busbar 5) is adjusted according to the actual application, creating a stepped width difference 50132 between the two types of copper busbars.

[0072] The heterogeneous welded copper busbar with directional conduction function of this application belongs to the field of structural design of power connectors, and specifically relates to a soft copper busbar and a hard copper busbar resistance welding assembly that realizes precise conduction of silver sheet 6 through a special geometric structure. It can be widely used in electrical connection scenarios that require strict control of post-weld dimensions.

[0073] The core structural innovation of the dissimilar copper busbar with directional flow diversion described in this application lies in its composite flow diversion system, namely, a groove that integrates positioning and diversion. A through-groove structure is provided on the copper busbar's welding surface. This structure includes a central positioning section, namely, a central positioning groove 5011, whose width is slightly larger than the size of the silver sheet 6 to create an assembly gap. It also includes a lateral flow diversion section, namely, a gradually expanding flow diversion channel 5012, which gradually expands toward the copper busbar's edge. It also includes a stepped containment structure, namely, a stepped width difference 50132, which forms the main weld on the working surface of the hard copper busbar (lower copper busbar 5) and a peripheral restraining platform at the end of the soft copper busbar (upper copper busbar 4), creating a molten metal containment space between the two platforms.

[0074] The technical benefits of the dissimilar copper busbars with directional flow guidance provided by this application are: first, dimensional control, ensuring the post-weld product dimensions remain consistent with the base material. Second, quality improvement, with the silver material forming a complete bond layer within the constraints of the flow guidance structure. Third, process compatibility, adapting to copper busbar combinations of varying thicknesses and materials. Fourth, cost optimization, eliminating post-weld secondary processing steps.

[0075] The advantages of the dissimilar copper busbar design with directional flow guidance in this application are short heating time, concentrated heat, small heat-affected zone, and low deformation and stress. No filler metal is required, welding costs are low, operation is simple, and mechanization and automation are easily achieved, resulting in high productivity.

[0076] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A heterogeneous welded copper busbar with directional flow guidance function, characterized in that: include: Copper busbar, including upper copper busbar and lower copper busbar; The silver sheet is located between the upper and lower copper bars; The copper bar has a central positioning groove for accommodating the silver sheet, and two sides of the central positioning groove are connected with a diversion channel, and one end of the diversion channel away from the central positioning groove is connected to a mechanical stopper; The mechanical stopper is located on both side edges of the copper busbar, and the mechanical stopper includes an inclined guide surface formed by chamfers on both side edges of the lower copper busbar; The horizontal cross-sectional profile of the central positioning groove is rectangular. When the silver sheet is placed in the central positioning groove, there is a gap between the edge of the unmelted silver sheet and the central positioning groove. The guide channel is a gradually expanding guide channel. From the central positioning groove to the mechanical stop portion, the width of the gradually expanding guide channel gradually widens, and the depth of the gradually expanding guide channel is constant and equal to the depth of the central positioning groove.

2. The heterogeneous welded copper busbar with directional flow guidance function according to claim 1, characterized in that: The two guide channels are symmetrically distributed on both sides of the central positioning groove, and the width of the guide channels is smaller than the length of any side of the central positioning groove.

3. The heterogeneous welded copper busbar with directional flow guidance function according to claim 1, characterized in that: The width of the mechanical stop portion is greater than the width of the guide channel and also greater than the width of the central positioning groove.

4. The heterogeneous welded copper busbar with directional flow guidance function according to claim 1, characterized in that: The inclined guide surface is chamfered at 45 degrees, and the inclined guide surface forms convex ridge lines on both side facades of the upper copper busbar.

5. The heterogeneous welded copper busbar with directional flow guiding function according to claim 1, characterized in that: The molten silver sheet contacts the inclined guide surface of the lower copper bar and flows obliquely downward, thereby forming a drooping overflow bag.

6. The heterogeneous welded copper busbar with directional flow guiding function according to claim 1, characterized in that: The mechanical stopper also includes a stepped width difference formed by the different widths of the upper copper bar and the lower copper bar, wherein the width of the lower copper bar is greater than the width of the upper copper bar, and two sides of the lower copper bar are more convex than two sides of the upper copper bar; The molten silver sheet infiltrates the two side elevations of the upper copper busbar and flows upward, thereby forming an upward overflow package.

7. The heterogeneous welded copper busbar with directional flow guiding function according to claim 6, characterized in that: The roughness Ra of the vertical surfaces on both sides of the upper copper busbar ranges from 0.8 μm to 3.2 μm.

8. The heterogeneous welded copper busbar with directional flow guiding function according to claim 1, characterized in that: The hardness of the lower copper bar is greater than that of the upper copper bar.

Images