A method for preparing a high-strength bonding force ultra-thin tin protective layer on a copper wire based on a magnetron sputtering method and a copper wire with a high-strength bonding force ultra-thin tin protective layer

Abstract

This invention discloses a method for preparing a high-strength, ultrathin tin protective layer on copper wire using magnetron sputtering, and the copper wire with the high-strength, ultrathin tin protective layer. The method includes the following steps: installing copper wire in an unwinding chamber; installing a Ni target and a Sn target in a vacuum deposition chamber; and evacuating the vacuum chamber until the vacuum range reaches 1~5×10⁻⁶. ‑3 Pa; Turn on the heating power and wait for the temperature to reach the set temperature; Start the conveyor belt and simultaneously clean the copper wire with plasma; Pre-sputter for 5-15 minutes; Sputter on the copper wire to obtain a nickel transition layer; Sputter on the copper wire to obtain a tin protective layer on the nickel transition layer; The coating process is complete. This invention uses radio frequency magnetron sputtering to deposit a nanoscale nickel transition layer and a tin protective layer sequentially on a copper wire, which can effectively improve the bonding force between the copper wire and the Sn layer, prevent the Sn layer from cracking and peeling off, improve the oxidation resistance of the copper wire, and thus extend the service life of the copper wire.

Description

Technical Field

[0001] This invention relates to the field of functional thin film materials technology, and in particular to a method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering, and a copper wire with a high-strength, ultrathin tin protective layer. Background Technology

[0002] Round copper wire, with its excellent electrical conductivity, thermal conductivity, and machinability, is widely used in wires and cables, electronic component leads, and precision signal transmission lines. However, in practical applications, the copper substrate readily reacts with oxygen and moisture in the air to form oxide layers such as copper oxide and cuprous oxide. This not only significantly increases the surface contact resistance of the wire, leading to a decrease in conductivity, but also affects subsequent welding and assembly processes. Therefore, the industry typically performs surface plating on copper wire to improve its oxidation and corrosion resistance.

[0003] Tin plating offers excellent resistance to atmospheric corrosion, solderability, and chemical stability, and is cost-effective, making it the preferred material for anti-oxidation coating of copper wires. Currently, conventional copper wire tin plating often uses micron-level thick coatings, typically 1-5 μm thick. While this achieves basic anti-oxidation effects, the thick coating increases the overall diameter of the wire, affecting precision winding and assembly performance in confined spaces. It also wastes tin material and increases production costs. For precision electronic round copper wires, there is an urgent need for submicron-level ultrathin tin plating to maintain the original wire diameter accuracy while ensuring anti-oxidation performance, thus meeting the requirements for precision and lightweight applications.

[0004] However, when the existing ultrathin tin plating process is directly applied to round copper wires, there are technical defects: 1) Round copper wires have a curved structure, and the current distribution and ion adsorption of the plating solution are uneven during the traditional electroplating process. The ultrathin plating layer is prone to problems such as circumferential thickness deviation, local pinholes, and incomplete plating, making it difficult to guarantee the integrity of the anti-oxidation barrier; 2) There is a strong atomic interdiffusion effect between copper and tin, which can form brittle Cu6Sn5 and Cu3Sn intermetallic compounds in a short period of time. This not only destroys the density of the tin layer, but also causes a significant decrease in the adhesion between the plating layer and the substrate, resulting in peeling, blistering, and detachment, directly losing the anti-oxidation effect; 3) Traditional electroplating processes have problems such as plating solution pollution, difficulty in waste liquid treatment, thicker plating layers, and high costs.

[0005] In existing technologies, some solutions attempt to improve coating performance by optimizing the plating solution formula and adjusting electroplating parameters, but these can only alleviate the adhesion problem of thick coatings. For the application scenarios of micro-nano-scale ultrathin tin layers and round copper wires, they cannot fundamentally solve the core problems of copper-tin interdiffusion, weak interfacial adhesion, poor coating uniformity, and poor oxidation resistance of the Sn layer. Summary of the Invention

[0006] To address the specific requirements of circular copper wires, micro / nano-scale, and high-bonding ultrathin tin plating, this invention develops a method for preparing a high-bonding ultrathin tin protective layer on copper wires using magnetron sputtering. This method effectively improves plating adhesion, blocks interdiffusion of copper and tin atoms, ensures circumferential uniformity and density of the plating layer, and is clean, controllable, and suitable for mass production.

[0007] A further technical problem to be solved by the present invention is to provide a copper wire with an ultra-thin tin protective layer having high bonding strength.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a high-strength, ultrathin tin protective layer on copper wires using magnetron sputtering includes the following steps:

[0010] S1: Install copper wire in the unwinding chamber, and install Ni target and Sn target in the vacuum deposition chamber. Ni target and Sn target are respectively connected to radio frequency power supply.

[0011] S2: Sequentially turn on the mechanical pump and molecular pump to evacuate until the vacuum range in the vacuum deposition chamber reaches 1~5×10⁻⁶. - 3 Pa;

[0012] S3: Turn on the heating power and set the temperature to 80~150℃;

[0013] S4: Once the temperature reaches the set temperature, start the conveyor belt and turn on the plasma power supply to clean the copper wire.

[0014] S5: Ar gas is introduced into the vacuum deposition chamber;

[0015] S6: Turn on the baffle of the vacuum deposition chamber and the RF power supply, and pre-sputter for 5~15 minutes;

[0016] S7: Adjust the power of the Ni target, turn off the baffle, and sputter the copper wire to obtain a nickel transition layer;

[0017] S8: Adjust the power of the Sn target, close the baffle, and sputter the copper wire onto the nickel transition layer to obtain a tin protective layer;

[0018] S9: Coating complete. Turn off the heating power and RF power.

[0019] In step S1, the Ni target and the Sn target are installed in two adjacent vacuum deposition chambers, respectively.

[0020] In step S1, there are four Ni targets, located at the top, bottom, front, and back positions of the copper wire.

[0021] In step S1, there are four Sn targets, located at the top, bottom, front, and back positions of the copper wire.

[0022] The target-to-substrate distance for the four Ni targets is 40-100 mm, and the target-to-substrate distance for the four Sn targets is 40-100 mm. Here, the target-to-substrate distance refers to the distance from the center of the target material to the copper wire.

[0023] The copper wire conveying speed during cleaning and sputtering is 2~8m / min.

[0024] In step S5, after Ar gas is introduced, the gas pressure in the vacuum deposition chamber where the Ni target is located is adjusted to 0.5~1.5 Pa, and the gas pressure in the vacuum deposition chamber where the Sn target is located is adjusted to 0.5~2 Pa.

[0025] The power of the Ni target is 10~50W; the power of the Sn target is 50~150W.

[0026] A copper wire with a high-strength, ultra-thin tin protective layer comprises a circular copper wire, the surface of which is sequentially plated with an ultra-thin nickel transition layer and an ultra-thin tin protective layer from the inside out; both the ultra-thin nickel transition layer and the ultra-thin tin protective layer are deposited using a radio frequency magnetron sputtering process.

[0027] The thickness of the ultrathin nickel transition layer is 10~50nm, and the thickness of the ultrathin tin protective layer is 200~550nm.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) The method for preparing a high-strength, ultrathin tin protective layer on copper wire in this invention employs radio frequency magnetron sputtering to deposit a nickel transition layer and a tin protective layer, respectively. The magnetron sputtered coating is physically vapor-deposited onto the copper substrate, resulting in a tight interface. Combined with the nano-roughened interface formed before plating, this significantly improves the adhesion between the coating and the copper layer. Furthermore, nickel exhibits excellent wettability and bonding strength with both the copper substrate and the tin layer, solving the problems of poor adhesion, peeling, blistering, and detachment in tin layers prepared using traditional techniques. Simultaneously, the ultrathin nickel transition layer has a dense, fine-grained structure, which completely blocks the interdiffusion of copper and tin atoms, preventing the formation of brittle intermetallic compounds, effectively blocking copper-tin interdiffusion, and extending the anti-oxidation lifespan. The entire process uses continuous magnetron sputtering, eliminating plating solution pollution and wastewater treatment issues. The thickness of the transition layer and tin layer can be flexibly adjusted by the conveyor belt speed and sputtering power, enabling continuous batch production of long-distance round copper wires.

[0030] (2) The present invention provides a method for preparing a high-strength, ultra-thin tin protective layer on copper wires as described above. The Ni target and Sn target used are both high-purity metal targets (99.99%), and four targets are sputtered simultaneously to ensure that the round copper wires are all placed within the sputtering glow, resulting in a uniform and dense coating.

[0031] (3) The present invention performs Ar plasma cleaning on the copper wire, which improves the surface roughness of the copper wire, which is conducive to improving the nucleation of Ni atoms on the surface of the copper wire and improving the bonding force between the coating and the surface of the copper wire; and the copper wire is subjected to primary heating, which can further improve the bonding force between the coating and the copper.

[0032] (4) The thickness of the Ni transition layer of the present invention is 10~50nm, which will not affect the conductivity of the copper wire; the Ni transition layer, Cu substrate and Sn protective layer have good physical compatibility and chemical affinity, which can form a tight interface contact, avoid interface gaps, and improve the bonding foundation from the root.

[0033] (5) The method for preparing a high-strength, ultra-thin tin protective layer on copper wire provided by the present invention is simple to operate, low in cost, and easy to industrialize. Attached Figure Description

[0034] Figure 1 X-ray diffraction analysis of the Sn protective layer prepared in Example 1;

[0035] Figure 2 This is a cross-sectional structure-thickness analysis of the Sn protective layer prepared in Example 2;

[0036] Figure 3 This is a cross-sectional structure-thickness analysis of the Sn protective layer prepared in Example 3. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0038] This invention employs radio frequency magnetron sputtering to deposit a nanoscale nickel transition layer and a tin protective layer sequentially on a copper wire. The prepared nanoscale Ni transition layer has a circumferentially uniform and dense microstructure, which can effectively improve the bonding force between the copper wire and the Sn layer, prevent the Sn layer from cracking and falling off, improve the oxidation resistance of the copper wire, and thus extend the service life of the copper wire.

[0039] Example 1

[0040] (1) Install copper wire in the unwinding chamber, and simultaneously install 4 Ni targets (99.99%) and 4 Sn targets (99.99%). The 4 Ni targets are placed in the first vacuum deposition chamber, positioned above, below, in front, and behind the copper wire, respectively; the 4 Sn targets are placed in the second vacuum deposition chamber, positioned above, below, in front, and behind the copper wire, respectively. The two vacuum deposition chambers are connected by a narrow channel, and each target is connected to the RF power supply of its respective vacuum deposition chamber. The Ni target-to-substrate distance is 40 mm, and the Sn target-to-substrate distance is 60 mm. Close both vacuum deposition chambers.

[0041] (2) Turn on the mechanical pump and molecular pump in sequence to evacuate until the vacuum range of the two vacuum deposition chambers reaches 2×10⁻⁶. -3 Pa;

[0042] (3) Turn on the heating power and set the temperature to 80℃;

[0043] (4) Once the temperature reaches the set temperature, adjust the copper wire conveying speed to 2m / min, and simultaneously turn on the ion source to clean the copper wire;

[0044] (5) Ar was introduced into the two vacuum deposition chambers respectively. The pressure in the first vacuum deposition chamber was adjusted to 0.5 Pa, and the pressure in the second vacuum deposition chamber was adjusted to 1 Pa.

[0045] (6) Turn on the baffles and RF power supply in the two vacuum deposition chambers in sequence, and pre-sputter for 5 minutes;

[0046] (7) Synchronously adjust the four radio frequency power supplies of the first vacuum deposition chamber to a power of 10W, close the baffle of the first vacuum deposition chamber, and start sputtering. The thickness of the resulting nickel transition layer is 15nm.

[0047] (8) Synchronously adjust the four radio frequency power supplies of the second vacuum deposition chamber to 80W, close the baffle of the second vacuum deposition chamber, start sputtering, and the thickness of the Sn coating obtained is 300nm;

[0048] (9) After the coating is completed, turn off the heating power supply, the radio frequency power supply in the first vacuum deposition chamber and the second vacuum deposition chamber to obtain a copper wire with a tin-plated layer with high bonding strength. The copper wire is then returned to the reel in the winding chamber.

[0049] The composition and structure of the Sn protective layer were analyzed using X-ray diffraction, such as... Figure 1 As shown. By Figure 1 It can be seen that the film is a pure Sn phase and no obvious impurity peaks appear.

[0050] Example 2

[0051] (1) Install copper wire in the unwinding chamber, and install 4 Ni targets (99.99%) and 4 Sn targets (99.99%). The 4 Ni targets are placed in vacuum deposition chamber 1, located above, below and in front of the copper wire respectively; the 4 Sn targets are placed in vacuum deposition chamber 2, located above, below and in front of the copper wire respectively. The two vacuum deposition chambers are connected by a narrow channel. Each target is connected to the radio frequency power supply of its respective vacuum deposition chamber. The Ni target base distance is 50 mm and the Sn target base distance is 60 mm. Close the two vacuum deposition chambers.

[0052] (2) Turn on the mechanical pump and molecular pump in sequence to evacuate until the vacuum range in both vacuum deposition chambers reaches 3×10⁻⁶. -3 Pa;

[0053] (3) Turn on the heating power and set the temperature to 100℃;

[0054] (4) Once the temperature reaches the set temperature, adjust the copper wire conveying speed to 4 m / min, and simultaneously turn on the ion source to clean the copper wire;

[0055] (5) Ar was introduced into the two vacuum deposition chambers respectively. The pressure in the first vacuum deposition chamber was adjusted to 0.8 Pa, and the pressure in the second vacuum deposition chamber was adjusted to 1.5 Pa.

[0056] (6) Turn on the baffles and RF power supply in the two vacuum deposition chambers in sequence, and pre-sputter for 7 minutes;

[0057] (7) Synchronously adjust the four radio frequency power supplies of the first vacuum deposition chamber to 20W, close the baffle, start sputtering, and the thickness of the resulting nickel transition layer is 20nm;

[0058] (8) Synchronously adjust the four radio frequency power supplies of the second vacuum deposition chamber to 100W, close the baffle, start sputtering, and the resulting Sn coating thickness is 380nm;

[0059] (9) After the coating is completed, turn off the heating power supply, the radio frequency power supply in the first vacuum deposition chamber and the second vacuum deposition chamber to obtain a copper wire with a tin-plated layer with high bonding strength. The copper wire is then retracted onto the reel in the winding chamber.

[0060] The thickness of the Sn layer was observed using a scanning electron microscope, such as Figure 2 As shown, the Sn protective layer is about 450 nm thick, and some small Sn grains can be observed.

[0061] Example 3

[0062] (1) Install copper wire in the unwinding chamber, and simultaneously install 4 Ni targets (99.99%) and 4 Sn targets (99.99%). The 4 Ni targets are placed in the first vacuum deposition chamber, located above, below, in front and behind the copper wire respectively; the 4 Sn targets are placed in the second vacuum deposition chamber, located above, below, in front and behind the copper wire respectively. The two vacuum deposition chambers are connected by a narrow channel. Each target is connected to the radio frequency power supply of its respective vacuum deposition chamber. The Ni target base distance is 50 mm, and the Sn target base distance is 60 mm. Close both vacuum deposition chambers.

[0063] (2) Turn on the mechanical pump and molecular pump in sequence to evacuate until the vacuum range in both vacuum deposition chambers reaches 2×10⁻⁶. -3 Pa;

[0064] (3) Turn on the heating power and set the temperature to 120℃;

[0065] (4) Once the temperature reaches the set temperature, adjust the copper wire conveying speed to 4 m / min, and simultaneously turn on the ion source to clean the copper wire;

[0066] (5) Ar was introduced into the two vacuum deposition chambers respectively. The pressure in the first vacuum deposition chamber was adjusted to 0.8 Pa, and the pressure in the second vacuum deposition chamber was adjusted to 1.5 Pa.

[0067] (6) Turn on the baffles and RF power supply in the two vacuum deposition chambers in sequence, and pre-sputter for 7 minutes;

[0068] (7) Synchronously adjust the four radio frequency power supplies of the first vacuum deposition chamber to 20W, close the baffle, start sputtering, and the thickness of the resulting nickel transition layer is 20nm;

[0069] (8) Synchronously adjust the four radio frequency power supplies of the second vacuum deposition chamber to 120W, close the baffle, start sputtering, and the resulting Sn coating thickness is 420nm;

[0070] (9) After the coating is completed, turn off the heating power supply, the radio frequency power supply in the first vacuum deposition chamber and the second vacuum deposition chamber to obtain a copper wire with a Sn protective layer with high bonding strength. The copper wire is then retracted onto the reel in the winding chamber.

[0071] The cross-sectional structure of the Sn protective layer was observed using a scanning electron microscope, such as... Figure 3 As shown, when the heating temperature is increased and the Sn target sputtering power is increased, the Sn thickness increases by approximately 516 nm, indicating that the Sn coating thickness can be effectively adjusted by regulating the Sn target sputtering power, while the Sn grain shape does not change significantly.

[0072] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. A method for preparing a high-strength, ultrathin tin protective layer on copper wires using magnetron sputtering, characterized in that, Includes the following steps: S1: Install copper wires on the tape reel in the unwinding chamber, and install Ni and Sn targets in the vacuum deposition chamber. The Ni and Sn targets are connected to the radio frequency power supply respectively. S2: Sequentially turn on the mechanical pump and molecular pump to evacuate the vacuum until the vacuum range in the vacuum deposition chamber reaches 1~5×10⁻⁶. -3 Pa; S3: Turn on the heating power and set the temperature to 80~150℃; S4: Once the temperature reaches the set temperature, start the conveyor belt and turn on the plasma power supply to perform plasma cleaning treatment on the copper wire. S5: Ar gas is introduced into the vacuum deposition chamber; S6: Turn on the baffle of the vacuum deposition chamber and the RF power supply, and pre-sputter for 5~15 minutes; S7: Adjust the power of the Ni target, turn off the baffle, and sputter the copper wire to obtain a nickel transition layer; S8: Adjust the power of the Sn target, close the baffle, and sputter the copper wire to obtain a tin protective layer on the nickel transition layer; S9: Coating complete. Turn off the heating power and RF power.

2. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 1, characterized in that, In step S1, the Ni target and the Sn target are installed in two adjacent vacuum deposition chambers, respectively.

3. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 2, characterized in that, In step S1, there are four Ni targets, located at the top, bottom, front, and back positions of the copper wire.

4. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 2, characterized in that, In step S1, there are 4 Sn targets, located at the top, bottom, front, and back positions of the copper wire.

5. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 3 or 4, characterized in that, The target-to-substrate distance for the four Ni targets is 40~100mm, and the target-to-substrate distance for the four Sn targets is 40~100mm.

6. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 1, characterized in that, The copper wire travel speed is 2-8 m / min during plasma cleaning and sputtering.

7. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 1, characterized in that, In step S5, after Ar gas is introduced, the pressure in the vacuum deposition chamber where the Ni target is located is adjusted to 0.5~1.5 Pa, and the pressure in the vacuum deposition chamber where the Sn target is located is adjusted to 0.5~2 Pa.

8. The method for preparing a high-strength, ultrathin tin protective layer on copper wires based on magnetron sputtering according to claim 1, characterized in that, The power of the Ni target is 10~50W; the power of the Sn target is 50~150W.

9. A copper wire with a high-strength, ultra-thin tin protective layer, characterized in that, The invention includes a circular copper wire, the surface of which is coated with an ultrathin nickel transition layer and an ultrathin tin protective layer from the inside out; both the ultrathin nickel transition layer and the ultrathin tin protective layer are deposited using a radio frequency magnetron sputtering process.

10. The copper wire with a high-strength, ultra-thin tin protective layer according to claim 9, characterized in that, The thickness of the ultrathin nickel transition layer is 10~50nm, and the thickness of the ultrathin tin protective layer is 200~550nm.

Images