A plastic surface metallization manufacturing process based on friction stir welding

Abstract

The application relates to a plastic surface metallization manufacturing process based on friction stir welding, which comprises the following steps: S1, a roughening stage; S2, a chemical plating-electroplating stage; S3, a friction stir welding stage: direct friction stir welding with a metal sheet. The direct friction stir lap welding process with a metal sheet adopted by the application can form firm metallurgical bonding between the metal transition layer and the metal sheet through metal bonding, element diffusion, recrystallization and the like, and can further strengthen the mechanical locking effect of the metal / plastic interface, and high-performance connection of metal / plastic heterogeneous materials is realized through the composite chemical plating-electroplating and friction stir welding process.

Description

Technical Field

[0001] This invention belongs to the field of metal / plastic heterogeneous material joining technology, and relates to a plastic surface metallization manufacturing process based on friction stir welding, specifically a manufacturing process for high-performance metallization of plastic surfaces using chemical plating-electroplating and friction stir welding. Background Technology

[0002] Plating a metal layer on the surface of plastic can alter the material's physicochemical properties. While retaining the inherent advantages of plastic, it imparts a series of metallic properties such as electrical conductivity, thermal conductivity, and magnetic permeability, thereby meeting product design requirements. An antenna is a transducer that converts electromagnetic wave signals into electrical signals. In antenna manufacturing, a highly conductive metal layer (such as gold, silver, or copper) is typically plated onto the surface of a plastic material with a low dielectric constant. The low dielectric constant and low dielectric loss rate of the plastic material reduce its consumption and influence on the electric field, while the highly conductive metal layer helps to maximize the conversion of electromagnetic wave signals into electrical signals, ensuring signal strength.

[0003] The harsh operating conditions faced by spacecraft antennas during use, such as strong vibrations and alternating high and low temperatures, place high demands on their interfacial bonding strength, temperature resistance, and vibration resistance. Common methods for metallizing plastic surfaces include physical vapor deposition (PVD), electroless plating, and electroplating. PVD primarily relies on intermolecular forces for bonding, resulting in relatively low bonding strength. Electroless plating achieves a combination of physical bonding and mechanical locking resulting from surface roughening, offering improved interfacial bonding compared to PVD. However, the thickness of electroless plating layers is typically limited to a few to tens of micrometers, making it difficult to meet the required metal layer thickness for antennas. While electroplating can thicken the metal layer compared to electroless plating, its interfacial bonding strength remains low, and electroplated metal layers often suffer from high porosity and poor density. Therefore, regardless of whether PVD, electroless plating, or electroplating is used, the resulting metal layers all suffer from insufficient bonding strength with the plastic substrate, making it difficult to meet the increasingly demanding service requirements under extreme operating conditions. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a plastic surface metallization manufacturing process based on friction stir welding. Specifically, the process of directly performing friction stir lap welding with a metal plate allows the metal transition layer and the metal plate to form a strong metallurgical bond through metal bonds, element diffusion, recrystallization, etc. At the same time, it can further enhance the mechanical locking effect of the metal / plastic interface. High-performance connection of metal / plastic heterogeneous materials is achieved through a composite chemical plating-electroplating and friction stir welding process.

[0005] The objective of this invention can be achieved through the following methods:

[0006] In a first aspect, the present invention provides a plastic surface metallization manufacturing process based on friction stir welding, comprising the following steps:

[0007] S1, Roughening stage: Creating pits on the surface of plastic materials;

[0008] S2, Chemical Plating-Electroplating Stage: The plastic material obtained in step S1 is subjected to chemical plating-electroplating to form a metal transition layer;

[0009] S3, Friction Stir Welding Stage: The metal plate is covered on the surface of the metal transition layer of the plastic material after step S2, and friction stir welding is performed to obtain a metal / plastic heterogeneous material component.

[0010] As one implementation, in step S1, the plastic material is a low-dielectric plastic material.

[0011] As one implementation, in step S1, the plastic material includes at least one of polyimide, polyetherimide, carbon fiber composite material, and polyetheretherketone.

[0012] As one implementation, in step S1, the method for creating the pits includes at least one of mechanical roughening, chemical roughening, and laser roughening. The surface roughness of the plastic material is increased by creating the pits.

[0013] In some embodiments, the surface roughness of the plastic material after roughening treatment is 1-3 μm.

[0014] As one implementation, the mechanical roughening includes at least one of knurling, shot peening, sandblasting, and sandpaper polishing.

[0015] In some embodiments, the method of creating the pits is chemical roughening.

[0016] As one implementation, in step S2, the metal transition layer is a highly conductive metal material.

[0017] As one implementation, in step S2, the metal transition layer includes at least one of a copper layer, a silver layer, and a gold layer.

[0018] In one implementation scheme, the thickness of the metal transition layer in step S2 is 3–50 micrometers. Electroless plating can prepare a metal transition layer 1–10 micrometers thick. If a thicker metal transition layer is required, it can be thickened by electroplating on top of electroless plating.

[0019] Furthermore, the electroless plating-electroplating includes both electroless plating and electroplating, both of which are conventional techniques in the field.

[0020] As one implementation scheme, step S3 includes the following specific steps of friction stir welding: covering a plastic material with a metal transition layer with a metal plate and placing it on the friction stir welding platform in an overlapping manner, and fixing it with a clamp. The process parameters for friction stir welding are set and the device is started. The welding process ends after the stirring head completes its movement along the specified trajectory.

[0021] In one implementation scheme, in step S3, the thickness of the metal plate is 0.5 to 2 mm.

[0022] As one implementation method, the metal plate is made of a highly conductive metal material.

[0023] As one implementation, the metal plate may include at least one of a copper layer, a silver layer, and a gold layer.

[0024] In this invention, the material of the metal transition layer used may be the same as or different from the material of the metal plate to be subsequently subjected to friction stir welding. If the metal transition layer is different from the material of the subsequently selected metal plate, the metal transition layer is required to be chemically plated or electroplated, and its coefficient of thermal expansion is low enough to facilitate metallurgical bonding between the plastic substrate and the metal plate, and between the metal transition layer and the metal plate.

[0025] In some embodiments, the metal plate and the metal transition layer are made of the same material.

[0026] As one implementation scheme, in step S3, the feed rate of the friction stir welding is 0.2-1.5 mm, the feed speed is 0.2-1.5 mm / s, the stirring head rotation speed is 200-2000 rpm, and the stirring head travel speed is 50-400 mm / min.

[0027] As one implementation, in step S3, at the end of the friction stir welding stage, the friction stir welding device is turned off, the fixture is opened, and the sample is removed.

[0028] Secondly, the present invention provides a metal / plastic heterogeneous material component prepared by the manufacturing process described above.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention first prepares a thin metal transition layer on the surface of a plastic material by mechanically or chemically roughening the surface and then chemically plating-electroplating. Subsequently, a thick metal layer with high interfacial bonding force is prepared by directly stirring and friction lap welding with a metal plate.

[0031] (1) The present invention improves the interfacial bonding force between the chemically plated metal overcoat and the plastic material by mechanically or chemically roughening the surface of the plastic material, thereby pre-forming the surface roughness of the material.

[0032] (2) The present invention prepares a metal transition layer that can fully fill the surface pits and form a physical bond with the plastic by chemical plating-electroplating. Then, it uses friction stir welding technology to lap weld with the metal plate. Through the strong metallurgical bond between the metal plate and the metal transition layer, the reliable connection between the metal plate and the plastic substrate is indirectly realized, which solves the problem that metal / plastic is difficult to form a direct connection through friction stir welding.

[0033] (3) In this invention, the stirring friction brings about a strong material thermo-mechanical-flow effect, which transmits torque through the metal transition layer near the surface of the plastic material, causing the shape of the pits on the surface of the plastic material to change irregularly and complexly, forming a strong "mortise and tenon structure" mechanical interlock, thereby greatly improving the interface bonding force of metal / plastic. Attached Figure Description

[0034] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0035] Figure 1 This is a schematic diagram of the metallization process for plastic materials; in which the non-metallic material is plastic.

[0036] Figure 2 A comparison of the metal / plastic interface before and after friction stir welding; the non-metal is plastic. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0038] It should be noted that the chemical plating and electroplating used in the following embodiments are conventional techniques in the art.

[0039] Example 1

[0040] This embodiment relates to a method for preparing copper plating on a polyimide surface, such as... Figure 1 The process diagram shows the following steps:

[0041] S1. The surface of polyimide is roughened by etching with an etching solution using a chemical roughening method. After roughening, the surface roughness of the polyimide is approximately 1.8 micrometers.

[0042] S2. Then, a 30-micron-thick copper transition layer is deposited on the polyimide surface by chemical plating and electroplating.

[0043] S3. A 3mm thick polyimide plate with a thin copper transition layer and a 2mm thick copper plate are overlapped and fixed to the friction stir welding table using a clamp. A needle-free cylindrical stirring head with a shoulder diameter of 11mm is used. After the stirring head initially presses down until it contacts the copper plate surface, it feeds 1mm at a speed of 0.2mm / s and a rotation speed of 600rpm. Then, it follows the specified welding trajectory at a welding speed of 100mm / s (i.e., the stirring head travel speed), and the welding process is stopped. At the end of the friction stir welding stage, the welding device is turned off, the clamp is opened, and the sample is removed.

[0044] The polyimide / copper friction stir lap welded dissimilar joint obtained in this embodiment has a well-formed weld surface, without welding defects such as incomplete fusion or surface grooves. There are no obvious cracks at the interface between the copper plating and the copper plate. However, the interface pits between the copper plating and the polyimide have become extremely irregular in shape, forming a pattern similar to... Figure 2 The strong "mortise and tenon structure" mechanical interlocking shown significantly improves the bonding strength of the metal / plastic interface, and the comparison of the metal / plastic interface before and after friction stir welding is as follows: Figure 2 As shown.

[0045] Compared with existing technologies, the polyimide / copper heterostructures prepared by the novel plastic surface metallization process based on friction stir welding proposed in this invention can simultaneously meet the dual requirements of antennas for metal layer thickness and interface bonding strength under harsh service environments.

[0046] Comparative Example 1

[0047] The preparation method of this comparative example is basically the same as that of Example 1, except that step S3 is omitted and friction stir welding is performed directly on the roughened polyimide surface. Due to the limited fluidity of metal, it is difficult for the metal plate to directly and densely fill the micro-pits on the polyimide surface during the friction stir process, and it is even more impossible to drive the pits to deform and form a strong mechanical interlock. Therefore, the metal plate and polyimide cannot form a connection in this comparative example.

[0048] Performance testing

[0049] Comparative Example 1 revealed that the metal plate could not directly bond with the polyimide without the presence of a metal transition layer. The joint obtained in Example 1 was tested for performance using a tensile shear test, and the tensile shear strength of the joint obtained in Example 1 reached over 24 MPa (tensile shear strength is obtained by dividing the tensile shear load by the fracture area).

[0050] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A plastic surface metallization manufacturing process based on friction stir welding, characterized in that, The method comprises the following steps: S1, roughening stage: manufacturing pits on the surface of the plastic material; The roughness of the surface of the plastic material after the roughening treatment is 1-3 μm; S2, electroless plating-electroplating stage: electroless plating-electroplating the plastic material obtained in step S1 to form a metal transition layer; A metal transition layer is prepared by electroless plating-electroplating, which can fill the pits on the surface and form a physical bond with the plastic, and then the lap welding with the metal plate is performed by using the friction stir welding technology, and the reliable connection between the metal plate and the plastic substrate is indirectly realized through the firm metallurgical bond between the metal plate and the metal transition layer; S3, friction stir welding stage: covering the metal plate on the surface of the metal transition layer of the plastic material after the treatment in step S2 to perform the friction stir welding, and obtaining the metal / plastic heterogeneous material component; The friction stir welding brings strong material thermal-mechanical-flow effects, and the torque is transmitted through the metal transition layer near the surface of the plastic material to promote the irregular and complex changes of the pit shape on the surface of the plastic material, and the strong "mortise and tenon structure" mechanical interlocking is formed.

2. The manufacturing process of claim 1, wherein, In step S1, the plastic material is a low dielectric plastic material.

3. The manufacturing process of claim 2, wherein, The plastic material comprises at least one of polyimide, polyetherimide, carbon fiber composite material, and polyether ether ketone.

4. The manufacturing process of claim 1, wherein, In step S1, the method for manufacturing the pits comprises at least one of mechanical roughening, chemical roughening, and laser roughening.

5. The manufacturing process of claim 4, wherein, The mechanical roughening comprises at least one of knurling, shot blasting, sand blasting, and sandpaper polishing.

6. The manufacturing process of claim 1, wherein, In step S2, the material of the metal transition layer is a high-conductivity metal material.

7. The manufacturing process of claim 6, wherein, The metal transition layer comprises at least one of a copper layer, a silver layer, and a gold layer, and the thickness of the metal transition layer is 3-50 μm.

8. The manufacturing process of claim 1, wherein, In step S3, the material of the metal plate is the same as that of the metal transition layer, and the thickness of the metal plate is 0.5-2 mm.

9. The manufacturing process of claim 1, wherein, In step S3, the feed amount of the friction stir welding is 0.2-1.5 mm, the feed speed is 0.2-1.5 mm / s, the rotation speed of the stirring head is 200-2000 rpm, and the travel speed of the stirring head is 50-400 mm / min.

10. A metal / plastic heterogeneous material component manufactured by the manufacturing process according to any one of claims 1-9.

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