Brazing filler metal for electrode connection of micro nickel wire and multi-strand silver-plated copper wire and flowability control method of brazing filler metal

Abstract

The invention discloses brazing filler metal for electrode connection of a fine nickel wire and a multi-strand silver-plated copper wire and a fluidity control method of the brazing filler metal. The brazing filler metal comprises the following components in parts by weight: 35 to 40 parts of AgCuZn, 7 to 9 parts of Ni, 2 to 3.5 parts of Cr, 0.8 to 1.5 parts of Mo and 1.3 to 1.5 parts of Li; the method comprises the following steps: adjusting a filament of a silver-plated copper wire to a divergent shape, placing the divergent filament in a horn-shaped channel, arranging the divergent filament upwards, vertically inserting the tail section of a fine nickel wire into the middle of the divergent filament downwards, adding powdery brazing filler metal and liquid brazing filler metal into the horn-shaped channel, and uniformly stirring the fine nickel wire and the divergent filament; the side wall of the horn-shaped channel is heated, the brazing filler metal located in the horn-shaped channel is kept in a molten state, the silver-plated copper wire is pulled down according to the preset speed to control the flowing state of the brazing filler metal, and in the process, filaments of the silver-plated copper wire are gradually folded and extrude the molten brazing filler metal. According to the method, it can be ensured that brazing filler metal smoothly and fully infiltrates gaps of base metal, and the mobility of the connection area of the superfine nickel wire and the multi-strand silver-plated copper wire can be accurately and flexibly controlled.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic component materials, and particularly relates to a solder for connecting a fine nickel wire with a multi-strand silver-plated copper wire electrode and a method for controlling its fluidity. Background Art

[0002] A developed component micro-wire pin connector and its morphology control method (see existing document CN118572401A for details) includes a micro-wire pin that is soldered to multiple strands of a conductor through a solder body. The multiple strands of the conductor are axially wrapped around the periphery of the micro-wire pin, with the axis of the micro-wire pin substantially coinciding with the axis of the conductor. The solder body is filled in all non-gaps in the multiple strands of the conductor and in the gaps between the multiple strands and the micro-wire pin. The multiple strands of the conductor are embedded in the solder body and "grasp" the micro-wire pin. This solution enables rapid and precise control of the micro-wire connector's morphology and facilitates precise control of its length. In the aforementioned solution, the multiple strands of the conductor must be adjusted to a divergent state and the solder must fully penetrate the gaps in the base material (fully immersing the gaps and wetting the base material) to achieve the corresponding functions and effects. How to ensure that the solder fully penetrates the gaps in the base material is one of the key technical issues that need to be addressed. Since the gaps between the multiple strands of wire are very small, it is a technical difficulty in this field to fully infiltrate the gaps in the base material with solder.

[0003] To achieve better wetting of the base metal with the solder, existing solutions almost always involve adding a flow agent (such as sodium chloride, potassium chloride, or boric acid) to the solder to improve its fluidity. These flow agents lower the solder's melting point and surface tension, allowing it to flow more easily during welding and resulting in a smoother weld. However, for solders with relatively high nickel content, even significantly increasing the flow agent content in these solutions still fails to fully wetting the base metal gaps. Summary of the Invention

[0004] The present invention aims to provide a solder for connecting a fine nickel wire with a multi-strand silver-plated copper wire electrode and a method for controlling its fluidity.

[0005] The present invention adopts the following technical solutions.

[0006] A solder for connecting a fine nickel wire to a multi-strand silver-plated copper wire electrode comprises the following raw materials and unavoidable impurities in parts by weight: 35-40 parts of AgCuZn, 7-9 parts of Ni, 2-3.5 parts of Cr, 0.8-1.5 parts of Mo, and 1.3-1.5 parts of Li.

[0007] Preferably, AgCuZn: 38 parts, Ni: 8 parts, Cr: 3 parts, Mo: 1.2 parts, Li: 1.4 parts.

[0008] Preferably, the solder is a powder with a particle size not greater than 60 mesh (ie, a particle size not greater than 0.25 mm).

[0009] A method for controlling the fluidity of the aforementioned solder comprises the following steps: Step 1: Adjust the silver-plated copper wire to a divergent shape; Step 2, placing the divergent filaments in the trumpet-shaped channel, with the divergent filaments facing upward; Step 3: Insert the end of the fine nickel wire vertically downward into the middle of the diverging filaments; Step 4, adding powdered solder and liquid solder into the trumpet-shaped channel; Step 5, heating the side wall of the trumpet-shaped channel to keep the solder in the trumpet-shaped channel in a molten state; Step 6: Pull down the silver-plated copper wire at a preset speed to control the flow state of the solder. During this process, the filaments of the silver-plated copper wire gradually shrink and squeeze the molten solder.

[0010] In the present invention, the fluidity of the solder is controlled by means of a welding tool. The welding tool includes a graphite piece 1 connected to the positive pole of the welding power supply, and a graphite piece 2 connected to the negative pole of the welding power supply. Both the graphite piece 1 and the graphite piece 2 are provided with arc grooves, and the two arc grooves can form a trumpet-shaped channel for accommodating the silver-plated copper wire, and the diameter of the lower section of the trumpet-shaped channel is equal to the outer diameter of the silver-plated copper wire; a cooling support block is provided on the wall below the graphite piece, and the through hole on the cooling support block is coaxially arranged with the trumpet-shaped channel, and the diameter of the through hole is equal to the outer diameter of the silver-plated copper wire; a screw lifting mechanism for vertically pulling down the silver-plated copper wire is provided below the cooling support block, and a clamp for clamping the silver-plated copper wire is provided on the lifting plate of the screw lifting mechanism. When the silver-plated copper wire needs to be pulled down vertically, the clamp is first controlled to rise to the target height and clamp the silver-plated copper wire, and then the clamp is controlled to move downward at a preset speed to achieve vertical pulling down of the silver-plated copper wire at the preset speed.

[0011] Furthermore, an oblique through hole is provided on the first or second graphite piece, and a movable injection needle is fitted in the oblique through hole. The tip of the injection needle can extend into the axis of the trumpet-shaped channel, and the injection needle is externally connected to a liquid solder injection system.

[0012] Furthermore, the step of adding powdered solder and liquid solder into the trumpet-shaped channel includes: Step 41: In the initial state, the tip of the injection needle just coincides with the side wall of the trumpet-shaped channel, and the injection needle is controlled to move upward until the tip of the injection needle extends into the axis of the trumpet-shaped channel; Step 42, adding a certain amount of powdered solder into the trumpet-shaped channel from above the channel; Step 43, start the liquid solder injection system to inject a set amount of liquid solder into the trumpet-shaped channel; Step 44, controlling the injection needle to retract to the initial state, at which point the tip of the injection needle just coincides with the side wall of the trumpet-shaped channel; Step 45: Start the cooling control system corresponding to the cooling support block.

[0013] In order to further improve the connection stability between the fine nickel wire and the multi-strand silver-plated copper wire electrode, a non-plain wall structure is adopted on the surface of the end section of the fine nickel wire.

[0014] In order to further improve the connection stability between the fine nickel wire and the multi-strand silver-plated copper wire electrode, the liquid solder injection point is located 2-5 mm above the root of the divergent filament. The root of the divergent filament is also the boundary area between the lower section and the upper section of the trumpet-shaped channel.

[0015] Beneficial effects: The solution of the present invention can not only ensure that the solder can smoothly and fully infiltrate the gaps in the base material (that is, fully infiltrate the gaps in the filaments of the multi-strand silver-plated copper wire and wet the filaments), but also can accurately and flexibly control the fluidity of the solder in the connection area between the fine nickel wire and the multi-strand silver-plated copper wire, and can extend the connection area between the fine nickel wire and the multi-strand silver-plated copper wire electrode to the root of the divergent filament, significantly improving the length and strength of the connection area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the process of connecting the fine nickel wire and the multi-strand silver-plated copper wire electrode in Example 1 Figure 1 (The thin wires of silver-plated copper wire are adjusted to a divergent shape and placed in a trumpet-shaped channel); Figure 2 Schematic diagram of the process of connecting the fine nickel wire and the multi-strand silver-plated copper wire electrode in Example 1 Figure 2 (The end of the fine nickel wire is inserted vertically downward into the middle of the diverging filaments); Figure 3 Schematic diagram of the process of connecting the fine nickel wire and the multi-strand silver-plated copper wire electrode in Example 1 Figure 3 (add powdered solder into the trumpet-shaped channel); Figure 4 Schematic diagram of the process of connecting the fine nickel wire and the multi-strand silver-plated copper wire electrode in Example 1 Figure 4 (adding liquid solder into the trumpet-shaped channel); Figure 5 Schematic diagram of the process of connecting the fine nickel wire and the multi-strand silver-plated copper wire electrode in Example 1 Figure 5 (Pull down the silver-plated copper wire at a preset speed). The arrow indicates the direction in which the filament gradually converges. DETAILED DESCRIPTION

[0017] The following, in conjunction with the accompanying drawings, provides a clear and complete description of the technical solutions of the present invention. It should be noted that the embodiments described are merely some, and not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that the connection (welding) method parameters (including welding current, welding voltage, and welding time), the specific volume, length, and diameter of the flared channel, and the amount of brazing material used in the present invention are calculated and determined by those skilled in the art based on the specifications of the parent material.

[0018] It should be noted that the main structure of the welding tool used in each embodiment is a developed structure, see document CN118572401A for details. In the present invention, a liquid solder injection structure is further disclosed based on the previously disclosed structure. Specifically, Figures 1 to 5 As shown, the welding tool includes a graphite piece 11 connected to the positive electrode of the welding power supply, and a graphite piece 2 12 connected to the negative electrode of the welding power supply. Graphite pieces 11 and 12 are both provided with arc grooves, which can form a trumpet-shaped channel 10 for accommodating the silver-plated copper wire 3. The diameter of the lower section of the trumpet-shaped channel 10 is equal to the outer diameter of the silver-plated copper wire 3. A cooling support block 13 is provided on the wall below the graphite piece. A through hole 14 on the cooling support block 13 is coaxially arranged with the trumpet-shaped channel 10. The diameter of the through hole 14 is equal to the outer diameter of the silver-plated copper wire 3. A useful A screw lifting mechanism is provided for vertically pulling down the silver-plated copper wire 3. A clamp for clamping the silver-plated copper wire 3 is provided on the lifting plate of the screw lifting mechanism. When the silver-plated copper wire 3 needs to be pulled down vertically, the clamp is first controlled to rise to the target height and clamp the silver-plated copper wire 3. Then, the clamp is controlled to move down at a preset speed to achieve vertically pulling down the silver-plated copper wire 3 at the preset speed. An oblique through hole 20 is provided on the graphite piece 11 or the graphite piece 2 12. A movable injection needle 21 is fitted in the oblique through hole 20. In the initial state, the tip of the injection needle 21 just coincides with the side wall of the trumpet-shaped channel 10 (as shown in FIG. 1 ). Figure 2 As shown), the aperture of the injection needle 21 is 0.45 mm, the tip of the injection needle 21 can extend into the axis of the trumpet-shaped channel 10, and the injection needle 21 is externally connected to the liquid solder injection system. Example 1

[0019] A solder for connecting fine nickel wires to multi-strand silver-plated copper wire electrodes. The powdered solder 6 uses a powder with a particle size of 100-150 mesh and includes the following raw materials and inevitable impurities in parts by weight: AgCuZn: 38 parts, Ni: 8 parts, Cr: 3 parts, Mo: 1.2 parts, and Li: 1.4 parts.

[0020] A method for controlling the fluidity of solder for connecting fine nickel wires to multi-strand silver-plated copper wire electrodes, using a welding tool to control the fluidity of the solder, comprises the following steps: Step 1, adjust the filaments 7 of the silver-plated copper wire 3 to a divergent shape; Step 2: Place the divergent filaments 7 in the trumpet-shaped channel 10, with the divergent filaments 7 facing upwards. Figure 1 As shown; Step 3, such as Figure 2 As shown, the end segment 9 of the fine nickel wire is vertically inserted downward into the middle of the diverging filament 7, with the lower end of the fine nickel wire 9 being 5 mm away from the root of the diverging filament (i.e., the lower end of the fine nickel wire 9 is 5 mm away from the lower end of the stripping area of ​​the silver-plated copper wire 3, which is also referred to as the boundary area between the lower section and the upper section of the trumpet-shaped channel). The surface of the fine nickel wire end segment 9 has a non-plain wall structure, specifically, etched points are machined on the surface of the fine nickel wire end segment 9; Step 4: Add powdered solder 6 and liquid solder 5 into the trumpet-shaped channel; specifically: Step 41, control the injection needle 21 to move upward until the tip of the injection needle 21 extends into the axis of the trumpet-shaped channel 10. The state at this time is as follows: Figure 3 As shown; Step 42, as Figure 3 As shown, a fixed amount of powdered solder 6 is added into the trumpet-shaped channel 10 from above, and the added powdered solder 6 is mainly distributed in the upper area of ​​the divergent filaments 7 and the periphery of the filaments 7; Step 43, start the liquid solder injection system, set the injection pressure to 0.35Mpa, and inject a set amount of liquid solder 5 into the trumpet-shaped channel. The state at this time is as follows: Figure 4 As shown, the injected liquid solder 5 mainly fills the area where the powdered solder 6 has not entered, including the lower area of ​​the divergent filaments 7 but located in the gaps between the multiple filaments 7; Step 44, as Figure 5 As shown, the injection needle 21 is controlled to retract to the initial state, at which point the tip of the injection needle 21 just coincides with the side wall of the trumpet-shaped channel 10; Step 45, start the cooling control system corresponding to the cooling support block 13; Step 5: heating the side wall of the trumpet-shaped channel 10 to keep the solder in the trumpet-shaped channel 10 in a molten state; In step 6, the silver-plated copper wire 3 is pulled down at a preset speed to control the flow of the solder. During this process, the filaments 7 of the silver-plated copper wire 3 gradually converge and squeeze the molten solder. When the silver-plated copper wire 3 is pulled down to the target position and removed, a joint is formed, connecting the fine nickel wire to the multi-strand silver-plated copper wire electrode. Example 2

[0021] A solder for connecting fine nickel wire to multi-strand silver-plated copper wire electrodes. The powdered solder 6 is a powder with a particle size of 100-150 mesh and comprises the following raw materials and unavoidable impurities in parts by weight: AgCuZn: 36 parts, Ni: 7 parts, Cr: 2.5 parts, Mo: 1 part, and Li: 1.5 parts. A method for controlling solder fluidity is provided, referring to Example 1, differing only in that the injection pressure of the liquid solder injection system is set to 0.4 MPa.

[0022] Comparative Example 1: Referring to Example 1, the difference from Example 1 is that in step 4, only powdered solder 6 is added into the trumpet-shaped channel, and the amount of the powdered solder 6 is the same as the total amount of solder in the two states in Example 1.

[0023] Comparative Example 2: Referring to Example 1, the difference between it and Example 1 is that in step 4, only liquid solder 5 is added into the trumpet-shaped channel, and the amount of the liquid solder 5 is the same as the total amount of solder in the two states in Example 1.

[0024] Comparative Example 3, referring to Example 1, differs from Example 1 in that: the powdered solder 6 uses powder with a particle size of 100-150 mesh, including the following raw materials and inevitable impurities in parts by weight, wherein, AgCuZn: 38 parts, Ni: 8 parts, Cr: 3 parts, Mo: 1.2 parts, Li: 1.4 parts, and sodium chloride 2 parts; in step 4, only the powdered solder 6 is added to the trumpet-shaped channel, and the amount of the powdered solder 6 is the same as the total amount of solder in the two states in Example 1.

[0025] Comparative Example 4 refers to Example 1, and the difference between Comparative Example 4 and Example 1 is that the injection pressure of the liquid solder injection system is set to 0.5 MPa.

[0026] Comparative Example 5 refers to Example 1, and the difference between Comparative Example 5 and Example 1 is that the injection pressure of the liquid solder injection system is set to 0.3 MPa.

[0027] The defect detection (RT) and dimensional detection were performed on the electrode connection joint samples of the fine nickel wire and the multi-strand silver-plated copper wire obtained in Example 1 and the comparative example. The results are shown in the table below.

[0028] It can be seen that the solutions of Example 1 and Example 2 effectively solved the problem that the solder was difficult to fully infiltrate the fine filament gaps of the multi-strand silver-plated copper wires, and significantly reduced joint defects.

[0029] In the present invention, specific steps are used to achieve smooth and sufficient infiltration of the base material gaps by the solder without a fluidizing agent (i.e., sufficient infiltration into the filament gaps of the multi-strand silver-plated copper wire and wetting the filaments). In particular, a specific operating method is adopted to add powdered solder and liquid solder to different areas in the trumpet-shaped channel, so that the solder can smoothly penetrate into the filament gaps, and effectively connect the wires and the micro-filaments in the process of pulling down and gathering the multi-strand silver-plated copper wires. In addition, precise and flexible control of the fluidity of the solder in the connection area between the micro-nickel wires and the multi-strand silver-plated copper wires is achieved, and the connection area between the micro-nickel wires and the multi-strand silver-plated copper wire electrodes can be extended to the roots of the divergent filaments, significantly improving the length and strength of the connection area.

Claims

1. A solder for connecting fine nickel wires to multi-strand silver-plated copper wire electrodes, characterized in that: It comprises the following raw materials and inevitable impurities in parts by weight, wherein, AgCuZn: 35-40 parts, Ni: 7-9 parts, Cr: 2-3.5 parts, Mo: 0.8-1.5 parts, and Li: 1.3-1.5 parts.

2. The solder according to claim 1, wherein: AgCuZn: 38 parts, Ni: 8 parts, Cr: 3 parts, Mo: 1.2 parts, Li: 1.4 parts.

3. The solder according to claim 1 or 2, characterized in that: The solder is a powder with a particle size not greater than 60 meshes.

4. A method for controlling the fluidity of solder according to claim 3, characterized in that the steps include: Step 1, adjusting the filaments (7) of the silver-plated copper wire (3) to a divergent shape; Step 2, placing the divergent filaments (7) in the trumpet-shaped channel (10), with the divergent filaments (7) facing upward; Step 3, inserting the end of the fine nickel wire (9) vertically downward into the middle of the diverging filament (7); Step 4, adding powdered solder (6) and liquid solder (5) into the trumpet-shaped channel; Step 5, heating the side wall of the trumpet-shaped channel (10) to keep the solder in the trumpet-shaped channel (10) in a molten state; Step 6: Pull down the silver-plated copper wire (3) at a preset speed to control the flow state of the solder. During this process, the filaments (7) of the silver-plated copper wire (3) gradually gather and squeeze the molten solder.

5. The method for controlling liquidity according to claim 4, wherein: The fluidity of the solder is controlled by means of a welding tool, the welding tool comprises a graphite piece (11) connected to the positive electrode of the welding power supply, a graphite piece (12) connected to the negative electrode of the welding power supply, and an arc groove is provided on each of the graphite piece (11) and the graphite piece (12), and the two arc grooves can form a trumpet-shaped channel (10) for accommodating the silver-plated copper wire (3), and the diameter of the lower section of the trumpet-shaped channel (10) is equal to the outer diameter of the silver-plated copper wire (3); a cooling support block (13) is provided on the wall below the graphite piece, and a through hole (1 4) coaxially arranged with the trumpet-shaped channel (10), the diameter of the through hole (14) is equal to the outer diameter of the silver-plated copper wire (3); a screw lifting mechanism for vertically pulling down the silver-plated copper wire (3) is provided below the cooling support block (13), and a clamp for clamping the silver-plated copper wire (3) is provided on the lifting plate of the screw lifting mechanism. When the silver-plated copper wire (3) needs to be vertically pulled down, the clamp is first controlled to rise to a target height and clamp the silver-plated copper wire (3), and then the clamp is controlled to move downward at a preset speed to achieve vertically pulling down the silver-plated copper wire (3) at the preset speed.

6. The method for controlling liquidity according to claim 5, characterized in that: An oblique through hole (20) is provided on the graphite piece 1 (11) or the graphite piece 2 (12). A movable injection needle (21) is fitted in the oblique through hole (20). The tip of the injection needle (21) can extend into the axis of the trumpet-shaped channel (10). The injection needle (21) is externally connected to a liquid solder injection system.

7. The method for controlling liquidity according to claim 6, wherein: The steps of adding powdered solder (6) and liquid solder (5) into the trumpet-shaped channel include: Step 41, controlling the injection needle (21) to move upward until the tip of the injection needle (21) extends into the axis of the trumpet-shaped channel (10); Step 42, adding a certain amount of powdered solder (6) into the trumpet-shaped channel (10) from above the channel; Step 43, start the liquid solder injection system and inject a set amount of liquid solder (5) into the trumpet-shaped channel; Step 44, controlling the injection needle (21) to retract to the initial state, at which point the tip of the injection needle (21) just coincides with the side wall of the trumpet-shaped channel (10); Step 45, start the cooling control system corresponding to the cooling support block (13).

8. The method for controlling liquidity according to claim 7, wherein: The surface of the end section (9) of the fine nickel wire adopts a non-light wall structure.

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