A method for metallizing the surface of a plastic substrate

Abstract

The invention discloses a plastic substrate surface metallization method, comprising the following steps: mechanically roughening the plastic substrate; chemically roughening the plastic substrate after the mechanical roughening; immersing the plastic substrate after the chemical roughening pretreatment in a roughening solution for chemical roughening; surface metallization of the plastic substrate after the roughening; the roughening solution comprises nitric acid with a concentration of 200ml / L-300ml / L, sulfuric acid with a concentration of 300ml / L-500ml / L, and ammonium bifluoride with a concentration of 100g / L-200g / L. In the present invention, the plastic substrate is subjected to mechanical roughening and chemical roughening treatment respectively, and the effects of the two are superimposed on each other, ensuring that the surface of the plastic substrate has a certain roughness to improve the adhesion of the coating, and when designing and manufacturing a coating with a smaller roughness, it is conducive to the close combination of the coating and the plastic substrate; and a relatively uniform and smooth surface morphology is maintained, thereby improving the quality and performance of the coating.

Description

Technical Field

[0001] The invention relates to the technical field of plastic substrate surface treatment, in particular to a plastic substrate surface metallization method. Background Art

[0002] Plastic metallization is a technology that covers the surface of a non-conductive plastic workpiece with a metal film layer to make the plastic substrate conductive and have electromagnetic properties. This technology plays a vital role in the field of wireless communications, especially in antenna manufacturing.

[0003] With the continuous development of wireless communication technology, the requirements for metallization of antenna plastic substrates are also increasing. Since the operating frequency of high-frequency antennas is high and the wavelength is short, the transmission and reception of electromagnetic waves are very sensitive to slight changes on the antenna surface. The roughness of the coating will directly affect the surface morphology of the antenna, and thus affect its electromagnetic performance. If the roughness of the metal coating is too large, it is easy to cause electromagnetic waves to scatter and reflect on the surface of the antenna, thereby reducing the radiation efficiency and receiving sensitivity of the antenna. In order to ensure the performance of the antenna, the process technology continues to advance in the direction of more precise control of the surface roughness of the metal coating. However, the roughness of the metal coating is too small to meet the bonding requirements of the metal coating and the plastic substrate, making the metal coating made on the surface of glass fiber reinforced polyphenylene sulfide / polyphenylene ether / ethylene plastic (pps, ppo, sps plastic) in the industry far greater than 1μm, which cannot meet the existing antenna coating requirements. Summary of the invention

[0004] The invention provides a plastic substrate surface metallization method to solve the problem in the prior art that when the roughness of the metal coating is too small, the bonding force between the metal coating and the plastic substrate is insufficient.

[0005] The present application provides a method for metallizing the surface of a plastic substrate, comprising the following steps: mechanically roughening a plastic substrate; performing a chemical roughening pretreatment on the plastic substrate after the mechanical roughening treatment; immersing the plastic substrate after the chemical roughening pretreatment in a roughening liquid for chemical roughening treatment; performing a surface metallization treatment on the plastic substrate after the roughening treatment; the roughening liquid contains nitric acid with a concentration of 200ml / L-300ml / L, sulfuric acid with a concentration of 300ml / L-500ml / L, and ammonium bifluoride with a concentration of 100g / L-200g / L.

[0006] According to the above technical means, mechanical roughening treatment is used to physically roughen the surface of the plastic substrate, which can effectively remove dirt and oxide layers on the surface and increase the roughness of the substrate surface. Chemical roughening treatment uses chemical reagents to react chemically with the substrate surface to achieve the purpose of roughening. Chemical roughening treatment can more finely control the roughness of the plastic substrate surface to achieve a relatively uniform level. In the present invention, the plastic substrate is subjected to mechanical roughening treatment and chemical roughening treatment respectively, and the effects of the two are superimposed on each other, ensuring that the surface of the plastic substrate has a certain roughness to improve the adhesion of the coating. When designing and manufacturing a coating with a smaller roughness, it is beneficial to closely combine the coating with the plastic substrate; and maintain a relatively uniform and smooth surface morphology, thereby improving the quality and performance of the coating.

[0007] Furthermore, the chemical roughening pretreatment specifically includes the following sub-steps: immersing the plastic substrate after mechanical roughening treatment into an expansion liquid for expansion treatment; immersing the plastic substrate after expansion treatment into concentrated sulfuric acid for acidification treatment.

[0008] According to the above technical means, the plastic substrate after mechanical roughening treatment is immersed in an expansion liquid for expansion treatment, which can change the surface roughness and wettability of the plastic substrate, thereby affecting its adhesion and contact performance with other materials.

[0009] Acidification is the process of using the dissolution and corrosion of acid to react with the surface of the plastic substrate. During the expansion process, some new structures or defects, such as microcracks or holes, are generated on the surface of the plastic substrate. These structures provide more reaction interfaces for the acid, making the acidification effect more significant. The acid can further erode these structures, making the plastic surface rougher or more porous. Acidification can also remove pollutants, oxides or other attachments on the surface of the plastic substrate, thereby improving the cleanliness and wettability of the surface, helping to enhance the adhesion and contact performance of the plastic substrate with other materials, and improving the electrical performance and signal transmission efficiency of the antenna.

[0010] Furthermore, the swelling fluid includes sulfate ester salts with a concentration of 16%-50%.

[0011] Furthermore, the immersion temperature of the expansion treatment is 20°C-60°C; and the immersion time of the expansion treatment is 5min-20min.

[0012] Furthermore, the concentration of sulfuric acid is 50%-100%.

[0013] Furthermore, the soaking temperature of the acidification treatment is 20°C-35°C; and the soaking time of the acidification treatment is 10min-20min.

[0014] Furthermore, the surface metallization treatment specifically includes the following sub-steps: subjecting the plastic substrate after chemical roughening treatment to surface activation pre-treatment; subjecting the plastic substrate after surface activation pre-treatment to chemical plating treatment so that a first metal layer is deposited on the surface of the plastic substrate; electroplating a second metal layer on the surface of the first metal layer; immersing the electroplated plastic substrate in a filling metal solution to electroplate a filling layer on the surface of the second metal layer, wherein the roughness of the filling layer is less than 1 μm; and electroplating a protective layer on the surface of the filling layer.

[0015] According to the above technical means, a certain amount of active particles can be adsorbed on the surface of the plastic substrate, which helps to enhance the adhesion between the plastic substrate and the metal coating.

[0016] The plastic substrate after the surface activation pretreatment is placed in chemical nickel or chemical copper solution to deposit a 0.2-0.5 μm nickel layer or copper layer bottom metal layer. Preferably, the present invention uses chemical nickel solution, and the chemical nickel plating uses alkaline chemical nickel, wherein the Ni2+ content is 3g / l-4g / l, the sodium content is 10g / l-15g / l, the pH range is 8-9.2, the reaction temperature is 30°C-50°C, the immersion time is 4min-10min, and the nickel layer formed has a phosphorus content of 3-5%.

[0017] A copper layer of about 2.5 μm is electroplated on a plastic substrate with a nickel layer on the surface by acid copper electroplating. The acid copper solution includes: copper sulfate with a content of 60g / L-90g / L, sulfuric acid with a content of 190g / L-210g / L, chloride ions with a content of 40g / L-100mg / L, a cylinder opener with a content of 2ml / L-4ml / L and a brightener with a content of 1.5ml / L-3ml / L. The reaction temperature is 18°C-33°C and the electroplating time is 10min-30min.

[0018] Furthermore, the surface activation pretreatment specifically includes the following sub-steps: immersing the chemically roughened plastic substrate in a colloidal palladium solution to perform colloidal palladium activation treatment; immersing the colloidal palladium activated plastic substrate in a debonding solution.

[0019] According to the above technical means, when the plastic substrate is placed in a palladium solution, the substrate surface is adsorbed or chemically reacted with palladium ions, thereby forming a palladium film on the surface of the plastic substrate. This film can not only change the surface properties of the plastic substrate, but also enhance the adhesion of the plastic substrate to other materials or components. The degumming solution is a chemical solution that can decompose or destroy the chemical bonds between glue molecules. The function of the degumming solution is to decompose the glue and separate it from the substrate surface. The process of placing the antenna plastic substrate in a palladium solution and degumming not only changes the surface properties of the antenna plastic substrate, but also ensures the cleanliness and flatness of the plastic substrate surface, providing good conditions for the subsequent metal plating layer.

[0020] Furthermore, the leveling metal solution contains copper sulfate with a concentration of 160g / L-220g / L, sulfuric acid with a concentration of 50g / L-70g / L, chloride ions with a concentration of 80mg / L-150mg / L, a cylinder opener with a concentration of 3ml / L-8ml / L, a brightener with a concentration of 0.4ml / L-0.6ml / L and a leveler with a concentration of 0.2ml / L-0.5ml / L.

[0021] Furthermore, the mechanical roughening treatment specifically includes the following sub-steps: sandblasting the surface of the plastic substrate; and ultrasonically cleaning the plastic substrate after the sandblasting.

[0022] According to the above technical means, during the sandblasting process, abrasive particles are sprayed at high speed onto the surface of the plastic substrate through special equipment, thereby removing dirt, oxides and other impurities thereon, providing a smoother and cleaner surface for subsequent coating or other surface treatments. At the same time, sandblasting can enhance the adhesion and corrosion resistance of the coating to the substrate. Due to the impact of the abrasive particles, the microstructure of the surface of the plastic substrate is changed, making it rougher, which helps the coating material to adhere better to the substrate.

[0023] The sandblasting process may cause some sand, dust or other tiny impurities to adhere to the surface of the plastic substrate. Ultrasonic cleaning of the antenna substrate after sandblasting can effectively remove these impurities attached to the surface and ensure the cleanliness of the substrate surface.

[0024] Beneficial effects achieved by the present invention:

[0025] Mechanical roughening is a physical roughening treatment of the surface of the plastic substrate, which can effectively remove dirt and oxide layers on the surface and increase the roughness of the substrate surface. Chemical roughening is a treatment that uses chemical reagents to react with the substrate surface to achieve the purpose of roughening. Chemical roughening can more finely control the roughness of the plastic substrate surface to a relatively uniform level. In the present invention, the plastic substrate is subjected to mechanical roughening treatment and chemical roughening treatment respectively, and the effects of the two are superimposed on each other, ensuring that the surface of the plastic substrate has a certain roughness to improve the adhesion of the coating. When designing and manufacturing a coating with a smaller roughness, it is beneficial to closely combine the coating with the plastic substrate; and a relatively uniform and smooth surface morphology is maintained, thereby improving the quality and performance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a specific flow chart of Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the hundred-grid test results of Example 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the hundred-grid test results of Example 2 of the present invention;

[0029] Figure 4 This is a schematic diagram of the hundred-grid test results of Comparative Example 1 of the present invention;

[0030] Figure 5 It is a schematic diagram of the hundred-grid test results of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific embodiments should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the specific technical solution of the present application will be further described in detail below in conjunction with the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0033] The technical solution of the present invention is described in detail below in conjunction with the specific drawings.

[0034] A plastic substrate surface metallization method comprises the following steps: mechanically roughening a plastic substrate; chemically roughening pretreatment a plastic substrate after the mechanical roughening treatment; immersing the plastic substrate after the chemical roughening pretreatment in a roughening liquid for chemical roughening treatment; and performing surface metallization treatment on the roughened plastic substrate; the roughening liquid comprises nitric acid with a concentration of 200 ml / L-300 ml / L, sulfuric acid with a concentration of 300 ml / L-500 ml / L, and ammonium bifluoride with a concentration of 100 g / L-200 g / L.

[0035] Mechanical roughening is a physical roughening treatment of the surface of the plastic substrate, which can effectively remove dirt and oxide layers on the surface and increase the roughness of the substrate surface. Chemical roughening is a treatment that uses chemical reagents to react with the substrate surface to achieve the purpose of roughening. Chemical roughening can more finely control the roughness of the plastic substrate surface to a relatively uniform level. In the present invention, the plastic substrate is subjected to mechanical roughening treatment and chemical roughening treatment respectively, and the effects of the two are superimposed on each other, ensuring that the surface of the plastic substrate has a certain roughness to improve the adhesion of the coating. When designing and manufacturing a coating with a smaller roughness, it is beneficial to closely combine the coating with the plastic substrate; and a relatively uniform and smooth surface morphology is maintained, thereby improving the quality and performance of the coating.

[0036] It can be understood that the present invention can use glass fiber reinforced polyphenylene sulfide plastic or glass fiber reinforced polyphenylene ether plastic or glass fiber reinforced ethylene plastic as the antenna substrate.

[0037] It can be understood that the chemical roughening pre-treatment specifically includes the following sub-steps: immersing the plastic substrate after the mechanical roughening treatment into an expansion liquid for expansion treatment; immersing the plastic substrate after the expansion treatment into concentrated sulfuric acid for acidification treatment.

[0038] The swelling fluid comprises a sulfate ester salt with a concentration of 16%-50%.

[0039] The immersion temperature of the expansion treatment is 20° C.-60° C.; the immersion time of the expansion treatment is 5 min-20 min.

[0040] The concentration of sulfuric acid is 50%-100%.

[0041] The soaking temperature of the acidification treatment is 20°C-35°C; the soaking time of the acidification treatment is 10min-20min.

[0042] Immersing the mechanically roughened plastic substrate in an expansion liquid for expansion treatment can change the surface roughness and wettability of the plastic substrate, thereby affecting its adhesion and contact properties with other materials.

[0043] Acidification is the process of using the dissolution and corrosion of acid to react with the surface of the plastic substrate. During the expansion process, some new structures or defects, such as microcracks or holes, are generated on the surface of the plastic substrate. These structures provide more reaction interfaces for the acid, making the acidification effect more significant. The acid can further erode these structures, making the plastic surface rougher or more porous. Acidification can also remove pollutants, oxides or other attachments on the surface of the plastic substrate, thereby improving the cleanliness and wettability of the surface, helping to enhance the adhesion and contact performance of the plastic substrate with other materials, and improving the electrical performance and signal transmission efficiency of the antenna.

[0044] It can be understood that the surface metallization treatment specifically includes the following sub-steps: subjecting the plastic substrate after chemical roughening treatment to surface activation pre-treatment; subjecting the plastic substrate after surface activation pre-treatment to chemical plating treatment so that a first metal layer is deposited on the surface of the plastic substrate; electroplating a second metal layer on the surface of the first metal layer; immersing the electroplated plastic substrate in a filling metal solution to electroplate a filling layer on the surface of the second metal layer, wherein the roughness of the filling layer is less than 1 μm; and electroplating a protective layer on the surface of the filling layer.

[0045] Surface activation pretreatment can make a certain amount of active particles adsorb on the surface of the plastic substrate, which helps to enhance the adhesion between the plastic substrate and the metal coating.

[0046] The plastic substrate after the surface activation pretreatment is placed in a chemical nickel or chemical copper solution to deposit a 0.2-0.5 μm nickel layer or copper layer as the bottom metal layer. Preferably, the present invention uses a chemical nickel solution, and the chemical nickel plating uses alkaline chemical nickel, wherein Ni 2+ The content is 3g / l-4g / l, the secondary sodium content is 10g / l-15g / l, the pH range is 8-9.2, the reaction temperature is 30℃-50℃, the soaking time is 4min-10min, and the nickel layer formed has a phosphorus content of 3%-5%.

[0047] A copper layer of about 2.5 μm is electroplated on a plastic substrate with a nickel layer on the surface by acid copper electroplating. The acid copper solution includes: copper sulfate with a content of 60g / L-90g / L, sulfuric acid with a content of 190g / L-210g / L, chloride ions with a content of 40g / L-100mg / L, a cylinder opener with a content of 2ml / L-4ml / L and a brightener with a content of 1.5ml / L-3ml / L. The reaction temperature is 18°C-33°C and the electroplating time is 10min-30min.

[0048] It can be understood that the surface activation pretreatment specifically includes the following sub-steps: immersing the plastic substrate after chemical roughening treatment in a colloidal palladium solution to perform colloidal palladium activation treatment; immersing the plastic substrate after colloidal palladium activation treatment in a debonding solution.

[0049] When the plastic substrate is placed in the palladium solution, the substrate surface is adsorbed or chemically reacted with the palladium ions, thereby forming a palladium film on the surface of the plastic substrate. This film can not only change the surface properties of the plastic substrate, but also enhance the adhesion of the plastic substrate to other materials or components. The debonding solution is a chemical solution that can decompose or destroy the chemical bonds between glue molecules. The function of the debonding solution is to decompose the glue and separate it from the substrate surface. The process of placing the antenna plastic substrate in the palladium solution and debonding not only changes the surface properties of the antenna plastic substrate, but also ensures the cleanliness and flatness of the plastic substrate surface, providing good conditions for the subsequent metallization layer.

[0050] It can be understood that the leveling metal solution contains copper sulfate with a concentration of 160g / L-220g / L, sulfuric acid with a concentration of 50g / L-70g / L, chloride ions with a concentration of 80mg / L-150mg / L, a cylinder opener with a concentration of 3ml / L-8ml / L, a brightener with a concentration of 0.4ml / L-0.6ml / L and a leveler with a concentration of 0.2ml / L-0.5ml / L.

[0051] It can be understood that the mechanical roughening treatment specifically includes the following sub-steps: sandblasting the surface of the plastic substrate; and ultrasonically cleaning the plastic substrate after the sandblasting.

[0052] During the sandblasting process, abrasive particles are sprayed at high speed onto the surface of the plastic substrate through special equipment to remove dirt, oxides and other impurities on it, providing a smoother and cleaner surface for subsequent coating or other surface treatments. At the same time, sandblasting can enhance the adhesion and corrosion resistance of the coating to the substrate. Due to the impact of the abrasive particles, the microstructure of the surface of the plastic substrate is changed, making it rougher, which helps the coating material adhere better to the substrate.

[0053] The sandblasting process may cause some sand, dust or other tiny impurities to adhere to the surface of the plastic substrate. Ultrasonic cleaning of the antenna substrate after sandblasting can effectively remove these impurities attached to the surface and ensure the cleanliness of the substrate surface.

[0054] It can be understood that after the protective layer is electroplated on the surface of the filling layer, the plastic substrate is cleaned and dried, and finally the finished product is packaged.

[0055] Embodiment 1

[0056] like Figure 1 As shown, this embodiment provides a method for metallizing the surface of a plastic substrate, and the steps are as follows:

[0057] Step 1, select a PPS+40% GF (glass fiber reinforced polyphenylene sulfide plastic) matrix.

[0058] Step 2, mechanical roughening treatment: 220# (mesh) brown corundum sand is used to water-blast the glass fiber reinforced polyphenylene sulfide plastic matrix to form a surface with uniform roughness of 0.3 μm on the plastic matrix.

[0059] Step 3, ultrasonic cleaning: remove the residual brown corundum sand and the like on the surface of the plastic substrate.

[0060] Step 4, expansion treatment: soak the plastic substrate in an organic expansion agent containing sulfuric acid ester salt, wherein the concentration of sulfuric acid ester salt is 16%, the soaking temperature is 20° C., and the soaking time is 5 minutes.

[0061] Step 5, acidification treatment: the plastic substrate is immersed in a concentrated sulfuric acid solution, wherein the sulfuric acid concentration is 50%, the immersion temperature is 20° C., and the immersion time is 10 min.

[0062] Step 6, chemical roughening treatment: the plastic substrate soaked in sulfuric acid is immersed in a roughening solution to make the surface of the substrate microscopically rough and form a large number of hydrophilic groups on the surface; wherein the roughening solution contains nitric acid with a concentration of 200 ml / L, sulfuric acid with a concentration of 300 ml / L and ammonium bifluoride with a concentration of 100 g / L, the immersion temperature is 25°C, and the immersion time is 12 min.

[0063] Step 7, colloidal palladium activation treatment: soak the plastic substrate in a colloidal palladium solution so that a certain amount of active palladium particles are adsorbed on the substrate surface; wherein the colloidal palladium solution includes Pd 2+ , concentration is 3g / lSnCl2 and concentration is 100ml / lHCl, the immersion temperature is 20℃, and the immersion time is 5min.

[0064] Step 8, degumming treatment: soak the plastic substrate in a degumming solution to remove the colloidal divalent tin around the palladium, making the palladium more catalytically active, wherein the degumming solution includes sulfuric acid with a concentration of 50g / l, the soaking temperature is 20°C, and the soaking time is 50S.

[0065] Step 9, chemical nickel plating: Place the plastic substrate in an alkaline chemical nickel solution to deposit a 0.2 μm thick nickel layer on the surface of the plastic substrate, wherein the alkaline chemical nickel solution contains 3 g / l Ni 2+ and sodium hypochlorite with a concentration of 10 g / l, the pH value of the alkaline chemical nickel solution is 8, the immersion temperature is 30°C, the immersion time is 4 minutes, and the phosphorus content of the nickel layer is 3%.

[0066] Step 10, copper electroplating: electroplate a 2.5 μm thick intermediate copper layer on the nickel layer, wherein the copper bath solution contains 60 g / L copper sulfate, 190 g / L sulfuric acid, 40 mg / L chloride ions, 2 ml / L of a tank opener and 1.5 ml / L of a brightener, the bath temperature is 18°C, and the electroplating time is 10 min.

[0067] Step 11, electroplating a leveling layer: electroplating a leveling copper layer on the copper layer, the roughness of the leveling copper layer is less than 1 μm, wherein the leveling acid copper solution contains copper sulfate with a concentration of 160 g / L, sulfuric acid with a concentration of 50 g / L, chloride ions with a concentration of 80 mg / L, a cylinder opener with a concentration of 3 ml / L, a brightener with a concentration of 0.4 ml / and a leveler with a concentration of 0.2 ml / L, the immersion temperature is 18°C, and the electroplating time is 8 min.

[0068] Step 12, surface protection: plate a silver layer on the surface of the filling layer.

[0069] The surface roughness of the glass fiber reinforced polyphenylene sulfide plastic substrate prepared by the above method is 0.807μm, and a coating test is performed on it. Figure 2 As shown, use a sharp steel needle to draw 4 to 6 parallel lines with a spacing of 1 mm on the coating to be inspected, and then draw 4 to 6 parallel lines perpendicular to them; there is no peeling or shedding of the coating at the intersection of the straight lines.

[0070] Example 2

[0071] This embodiment provides a method for metallizing the surface of a plastic substrate, the steps of which are as follows:

[0072] Step 1, select a PPS+40% GF (glass fiber reinforced polyphenylene sulfide plastic) matrix.

[0073] Step 2, mechanical roughening treatment: 400# (mesh) brown corundum sand is used to water-blast the glass fiber reinforced polyphenylene sulfide plastic matrix to form a surface with uniform roughness of 1.1 μm on the plastic matrix.

[0074] Step 3, ultrasonic cleaning: remove the residual brown corundum sand and the like on the surface of the plastic substrate.

[0075] Step 4, expansion treatment: soak the plastic substrate in an organic expansion agent containing sulfuric acid ester salt, wherein the concentration of sulfuric acid ester salt is 50%, the soaking temperature is 60° C., and the soaking time is 20 minutes.

[0076] Step 5, acidification treatment: immerse the plastic substrate in a concentrated sulfuric acid solution, wherein the sulfuric acid concentration is 100%, the immersion temperature is 35° C., and the immersion time is 20 minutes.

[0077] Step 6, chemical roughening treatment: soak the plastic substrate soaked in sulfuric acid in a roughening solution, so that the surface of the substrate is microscopically rough and a large number of hydrophilic groups are formed on the surface; wherein the roughening solution contains 300 ml / L nitric acid, 500 ml / L sulfuric acid and 200 g / L ammonium bifluoride, the soaking temperature is 30°C, and the soaking time is 25 min.

[0078] Step 7, colloidal palladium activation treatment: soak the plastic substrate in a colloidal palladium solution so that a certain amount of active palladium particles are adsorbed on the surface of the substrate; wherein the colloidal palladium solution includes Pd2+ with a concentration of 30ppm, SnCl2 with a concentration of 10g / l and HCl with a concentration of 120ml / l, the soaking temperature is 35°C, and the soaking time is 15min.

[0079] Step 8, degumming treatment: soak the plastic substrate in a degumming solution to remove the colloidal divalent tin around the palladium, making the palladium more catalytically active, wherein the degumming solution includes sulfuric acid with a concentration of 70g / l, the soaking temperature is 45°C, and the soaking time is 80S.

[0080] Step 9, chemical nickel plating: Place the plastic substrate in an alkaline chemical nickel solution to deposit a 0.5 μm thick nickel layer on the surface of the plastic substrate, wherein the alkaline chemical nickel solution contains 4 g / l Ni 2+ and sodium hypochlorite with a concentration of 15 g / l, the pH value of the alkaline chemical nickel solution is 9.2, the immersion temperature is 50°C, the immersion time is 10 min, and the phosphorus content of the nickel layer is 5%.

[0081] Step 10, copper electroplating: electroplate a 2.4 μm thick intermediate copper layer on the nickel layer, wherein the copper bath solution contains 90 g / L copper sulfate, 210 g / L sulfuric acid, 100 mg / L chloride ions, 4 ml / L of a tank opener and 3 ml / L of a brightener, the bath temperature is 33°C, and the electroplating time is 30 min.

[0082] Step 11, electroplating a leveling layer: electroplating a leveling copper layer on the copper layer, the roughness of the leveling copper layer is less than 1 μm, wherein the leveling acid copper solution contains copper sulfate with a concentration of 220 g / L, sulfuric acid with a concentration of 70 g / L, chloride ions with a concentration of 150 mg / L, a cylinder opener with a concentration of 8 ml / L, a brightener with a concentration of 0.6 ml / , and a leveler with a concentration of 0.5 ml / L, the immersion temperature is 33°C, and the electroplating time is 20 min.

[0083] Step 12, surface protection: copper protection is performed on the surface of the filled copper plating layer.

[0084] The surface roughness of the glass fiber reinforced polyphenylene sulfide plastic substrate prepared by the above method is 0.860μm, and a coating test is performed on it. Figure 3 As shown, the 3M tape is used to stick the test. Specifically, the electroplating layer of the tested part is cut with a knife, and then the 3M tape is pressed flat on the surface by hand and stuck on the surface, and then pulled upward at a 45-degree angle at a uniform speed. After pulling it down, there is no block falling off on the surface of the plating layer.

[0085] Comparative Example 1

[0086] The method for metallizing the surface of a plastic substrate provided in this comparative example is different from that in Example 1 in that the steps of expansion treatment, acidification treatment and chemical roughening treatment are missing. The specific steps are as follows:

[0087] Step 1, select a PPS+40% GF (glass fiber reinforced polyphenylene sulfide plastic) matrix.

[0088] Step 2, mechanical roughening treatment: 220# (mesh) brown corundum sand is used to water-blast the glass fiber reinforced polyphenylene sulfide plastic matrix to form a surface with uniform roughness of 0.3 μm on the plastic matrix.

[0089] Step 3, ultrasonic cleaning: remove the residual brown corundum sand and the like on the surface of the plastic substrate.

[0090] Step 4, colloidal palladium activation treatment: soak the plastic substrate in a colloidal palladium solution so that a certain amount of active palladium particles are adsorbed on the surface of the substrate; wherein the colloidal palladium solution includes Pd 2+ , concentration is 3g / lSnCl2 and concentration is 100ml / lHCl, the immersion temperature is 20℃, and the immersion time is 5min.

[0091] Step 5, degumming treatment: soak the plastic substrate in a degumming solution to remove the colloidal divalent tin around the palladium, making the palladium more catalytically active, wherein the degumming solution includes sulfuric acid with a concentration of 50g / l, the soaking temperature is 20°C, and the soaking time is 50S.

[0092] Step 6, chemical nickel plating: Place the plastic substrate in an alkaline chemical nickel solution to deposit a 0.2 μm thick nickel layer on the surface of the plastic substrate, wherein the alkaline chemical nickel solution contains 3 g / l Ni 2+ and sodium hypochlorite with a concentration of 10 g / l, the pH value of the alkaline chemical nickel solution is 8, the immersion temperature is 30°C, the immersion time is 4 minutes, and the phosphorus content of the nickel layer is 3%.

[0093] Step 7, copper electroplating: electroplate a 2.5 μm thick intermediate copper layer on the nickel layer, wherein the copper bath solution contains 60 g / L copper sulfate, 190 g / L sulfuric acid, 40 mg / L chloride ions, 2 ml / L of a tank opener and 1.5 ml / L of a brightener, the bath temperature is 18°C, and the electroplating time is 10 min.

[0094] Step 8, electroplating a leveling layer: electroplating a leveling copper layer on the copper layer, the roughness of the leveling copper layer is less than 1 μm, wherein the leveling acid copper solution contains copper sulfate with a concentration of 160 g / L, sulfuric acid with a concentration of 50 g / L, chloride ions with a concentration of 80 mg / L, a cylinder opener with a concentration of 3 ml / L, a brightener with a concentration of 0.4 ml / and a leveler with a concentration of 0.2 ml / L, the immersion temperature is 18°C, and the electroplating time is 8 min.

[0095] Step 9, surface protection: plate a silver layer on the surface of the filling layer.

[0096] The surface of the glass fiber reinforced polyphenylene sulfide plastic substrate prepared by the above method was subjected to a coating test. Figure 4 As shown, use a sharp steel needle to draw 4 to 6 parallel lines with a spacing of 1 mm on the coating to be inspected, and then draw 4 to 6 parallel lines perpendicular to them; at the intersection of the straight lines, there is a large area of ​​coating peeling and shedding.

[0097] Comparative Example 2

[0098] The method for metallizing the surface of a plastic substrate provided in this comparative example is different from that in Example 2 in that the steps of expansion treatment, acidification treatment and chemical roughening treatment are missing. The specific steps are as follows:

[0099] Step 1, select a PPS+40% GF (glass fiber reinforced polyphenylene sulfide plastic) matrix.

[0100] Step 2, mechanical roughening treatment: 400# (mesh) brown corundum sand is used to water-blast the glass fiber reinforced polyphenylene sulfide plastic matrix to form a surface with uniform roughness of 1.1 μm on the plastic matrix.

[0101] Step 3, ultrasonic cleaning: remove the residual brown corundum sand and the like on the surface of the plastic substrate.

[0102] Step 4, colloidal palladium activation treatment: soak the plastic substrate in a colloidal palladium solution so that a certain amount of active palladium particles are adsorbed on the surface of the substrate; wherein the colloidal palladium solution includes Pd2+ with a concentration of 30ppm, SnCl2 with a concentration of 10g / l and HCl with a concentration of 120ml / l, the soaking temperature is 35°C, and the soaking time is 15min.

[0103] Step 5, degumming treatment: soak the plastic substrate in a degumming solution to remove the colloidal divalent tin around the palladium, making the palladium more catalytically active, wherein the degumming solution includes sulfuric acid with a concentration of 70g / l, the soaking temperature is 45°C, and the soaking time is 80S.

[0104] Step 6, chemical nickel plating: Place the plastic substrate in an alkaline chemical nickel solution to deposit a 0.5 μm thick nickel layer on the surface of the plastic substrate, wherein the alkaline chemical nickel solution contains 4 g / l Ni 2+ and sodium hypochlorite with a concentration of 15 g / l, the pH value of the alkaline chemical nickel solution is 9.2, the immersion temperature is 50°C, the immersion time is 10 min, and the phosphorus content of the nickel layer is 5%.

[0105] Step 7, copper electroplating: electroplate a 2.4 μm thick intermediate copper layer on the nickel layer, wherein the copper bath solution contains 90 g / L copper sulfate, 210 g / L sulfuric acid, 100 mg / L chloride ions, 4 ml / L of a tank opener and 3 ml / L of a brightener, the bath temperature is 33°C, and the electroplating time is 30 min.

[0106] Step 8, electroplating a leveling layer: electroplating a leveling copper layer on the copper layer, the roughness of the leveling copper layer is less than 1 μm, wherein the leveling acid copper solution contains copper sulfate with a concentration of 220 g / L, sulfuric acid with a concentration of 70 g / L, chloride ions with a concentration of 150 mg / L, a cylinder opener with a concentration of 8 ml / L, a brightener with a concentration of 0.6 ml / , and a leveler with a concentration of 0.5 ml / L, the immersion temperature is 33°C, and the electroplating time is 20 min.

[0107] Step 9, surface protection: perform copper protection on the surface of the filled copper plating layer.

[0108] The surface of the glass fiber reinforced polyphenylene sulfide plastic substrate prepared by the above method was subjected to a coating test. Figure 5 As shown, the 3M tape sticking method is adopted. Specifically, the electroplating layer of the part to be tested is scratched with a knife, and then the 3M tape is pressed flat on the surface by hand and attached to the surface, and then pulled upward at a 45-degree angle at a uniform speed. After pulling it down, there are many pieces of falling off on the surface of the coating.

[0109] The serial numbers of the embodiments of the present application are only for description and do not represent the advantages and disadvantages of the embodiments. The above are only preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for metallizing a plastic substrate surface, characterized in that: The following steps are involved: Mechanically roughening the plastic matrix; The plastic substrate after mechanical roughening treatment is subjected to chemical roughening pretreatment, and the chemical roughening pretreatment specifically includes the following sub-steps: immersing the plastic substrate after mechanical roughening treatment in an expansion liquid for expansion treatment, immersing the plastic substrate after expansion treatment in concentrated sulfuric acid for acidification treatment, wherein the expansion liquid includes a sulfuric acid ester salt with a concentration of 16%-50%, the immersion temperature of the expansion treatment is 20°C-60°C, and the immersion time of the expansion treatment is 5min-20min; the immersion temperature of the acidification treatment is 20°C-35°C, and the immersion time of the acidification treatment is 10min-20min; The plastic substrate after chemical roughening pretreatment is immersed in a roughening liquid to perform chemical roughening treatment; Performing surface metallization treatment on the roughened plastic substrate; The roughening solution contains nitric acid with a concentration of 200 ml / L-300 ml / L, sulfuric acid with a concentration of 300 ml / L-500 ml / L, and ammonium bifluoride with a concentration of 100 g / L-200 g / L.

2. A method for metallizing a plastic substrate surface according to claim 1, characterized in that: The surface metallization treatment specifically includes the following sub-steps: The plastic substrate after chemical roughening treatment is subjected to surface activation pretreatment; The plastic substrate after the surface activation pretreatment is subjected to chemical plating treatment, so that a first metal layer is deposited on the surface of the plastic substrate; Electroplating a second metal layer on the surface of the first metal layer; Immersing the electroplated plastic substrate in a leveling metal solution to electroplate a leveling layer on the surface of the second metal layer, wherein the roughness of the leveling layer is less than 1 μm; A protective layer is electroplated on the surface of the filling layer.

3. A method for metallizing a plastic substrate surface according to claim 2, characterized in that: The surface activation pretreatment specifically comprises the following sub-steps: The plastic substrate after chemical roughening treatment is immersed in a colloidal palladium solution to perform colloidal palladium activation treatment; The plastic substrate activated by the colloidal palladium is immersed in a debonding solution.

4. A method for metallizing a plastic substrate surface according to claim 2, characterized in that: The leveling metal solution comprises copper sulfate with a concentration of 160g / L-220g / L, sulfuric acid with a concentration of 50g / L-70g / L, chloride ions with a concentration of 80mg / L-150mg / L, a cylinder opener with a concentration of 3ml / L-8ml / L, a brightener with a concentration of 0.4ml / L-0.6ml / L and a leveler with a concentration of 0.2ml / L-0.5ml / L.

5. A method for metallizing a plastic substrate surface according to claim 1, characterized in that: The mechanical roughening treatment specifically includes the following sub-steps: Sandblasting the surface of the plastic substrate; The plastic substrate after sandblasting is ultrasonically cleaned.

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