Shielding shell for assembly dielectric filter and surface metallization process thereof

Abstract

The invention discloses a shielding shell for an assembly dielectric filter, and the shielding shell comprises a plastic substrate and at least two metal conductor layers, the two metal conductor layers are made of different metal materials, a diffusion layer for metal atom interpenetration is formed between the two metal conductor layers, and the average thickness of the diffusion layer is 50-100 nm. The invention further discloses a surface metallization process of the shielding shell for the assembly dielectric filter. According to the invention, the plastic shell is adopted as a base material to be combined with the metal coating, a traditional metal material is replaced, the weight of an assembly part is reduced, and meanwhile, risks caused by a metal shielding shell are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of dielectric filter materials and manufacturing, and in particular to a shielding shell for an assembled dielectric filter and a preparation method thereof, a dielectric filter, and a communication antenna. Background Art

[0002] A dielectric filter is a device that selects frequencies based on the electromagnetic properties of dielectric materials. It uses the characteristics of dielectric constants and magnetic permeabilities of dielectric materials that change with frequency to filter signals of different frequencies. Dielectric filters have the advantages of small size, light weight, and low insertion loss, and are widely used in wireless communications, radar, satellite communications, and other fields.

[0003] In electronic devices, electromagnetic radiation is an issue that cannot be ignored. When electronic devices are working, they will generate electromagnetic radiation of a certain intensity. These electromagnetic radiations may interfere with dielectric filters and affect the performance of the filters. Especially when the intensity of electromagnetic radiation is high, it may cause resonance and saturation in the filter, resulting in filter failure. A shielding shell is a device used to isolate electromagnetic radiation. It can effectively block the propagation of electromagnetic radiation and reduce the impact of electromagnetic radiation on dielectric filters. In electronic devices, adding a shielding shell can improve the anti-interference ability of the device and ensure the stability and reliability of signal transmission.

[0004] At present, the shielding shell used in the assembled dielectric filter is generally made of metal, often aluminum alloy with plating. This kind of metal shielding shell has the following main defects: 1. The metal shielding shell has a certain effect in electromagnetic wave shielding, but its shielding effect is often affected by many factors. For example, the electrical conductivity and magnetic permeability of the metal will affect the reflection and transmission of electromagnetic waves, thereby affecting the shielding effect. 2. Metal materials are susceptible to oxidation and corrosion in humid or corrosive environments, which affects their service life and shielding effect. 3. Metal shielding shells usually have a high density and weight, which will increase the overall weight and manufacturing cost of the filter. Especially in some application scenarios with strict requirements on weight and cost, metal shielding shells may become an unfavorable factor. 4. Due to the difference in the thermal expansion coefficient of the metal shell and the PCB board and ceramics, the product solder joints crack after high and low temperature changes, and there is a reliability risk in long-term use. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a shielding shell for an assembly dielectric filter, which uses a plastic shell as a base material combined with a metal coating to replace traditional metal materials, reduce the weight of the assembly, and avoid the risks brought by the metal shielding shell.

[0006] To solve the above problems, the technical solutions adopted in this application are as follows:

[0007] An embodiment of the present application provides a shielding shell for an assembled dielectric filter, comprising a plastic substrate and at least two metal conductor layers, wherein the two metal conductor layers are made of different metal materials, and a diffusion layer in which metal atoms mutually penetrate is formed between the two metal conductor layers, wherein the thickness of the diffusion layer is 50-100 nm.

[0008] As a further preferred scheme, the metal conductor layer described in the embodiment of the present application includes at least a first metal conductor layer and a second metal conductor layer, the first metal conductor layer and the second metal conductor layer are made of different metal materials, and the metal atoms of the first metal conductor layer and the second metal conductor layer penetrate each other to form a diffusion layer.

[0009] As a further preferred scheme, a third metal conductor layer is arranged between the first metal conductor layer and the second metal conductor layer described in the embodiment of the present application, and there is a diffusion layer in which metal atoms permeate each other between the third metal conductor layer and the first metal conductor layer and the second metal conductor layer; the thickness of the third metal conductor layer is 2.0 to 4.0 μm.

[0010] As a further preferred solution, a metal welding layer is further provided on the surface of the second metal conductor layer described in the embodiment of the present application, and the thickness of the metal welding layer is 3.0 to 6.0 μm.

[0011] As a further preferred solution, the plastic substrate described in the embodiment of the present application is polyetherimide or polyphenylene sulfide.

[0012] As a further preferred solution, the material of the first metal conductor layer described in the embodiment of the present application is Ni or Pd, and the thickness of the first metal conductor layer is 0.4-1.0 μm.

[0013] As a further preferred solution, the material of the second metal conductor layer described in the embodiment of the present application is one of Ni, Pd, and nickel-copper alloy; the thickness of the second metal conductor layer is 2.0-4.0 μm.

[0014] The present application also provides a surface metallization process for a shielding shell for an assembly dielectric filter, comprising:

[0015] Pretreatment: Clean the surface of the plastic substrate to remove oil, dust and other impurities on the surface. After cleaning, perform roughening treatment to increase the surface roughness.

[0016] Sensitization treatment: the pre-treated plastic substrate is immersed in the sensitizing solution, so that the surface of the plastic substrate fully absorbs the metal ions in the sensitizing solution, and then it is taken out and rinsed to remove the residual sensitizing solution on the surface, and a sensitized layer is formed after drying;

[0017] Activation treatment: After the sensitized layer is formed, the plastic substrate is immersed in the activation solution to reduce the metal ions in the sensitized layer to metal atoms and form metal catalytic centers;

[0018] Forming a first metal conductor layer: forming a first metal conductor layer on the surface of the activated plastic substrate;

[0019] Forming a second metal conductor layer: forming a second metal conductor layer on the surface of the first metal conductor layer.

[0020] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, in the pretreatment step, the surface of the plastic substrate is cleaned with alkaline solution, and the roughness of the surface of the plastic substrate is increased by sandpaper polishing or sandblasting.

[0021] As a further preferred scheme, in the surface metallization process described in the embodiment of the present application, during the sensitization treatment, the sensitizing solution includes 45-55 g / L of stannous chloride, 10-15 mL / L of hydrochloric acid and 5-8 g / L of tin particles; the treatment time is 20-30 minutes, and the drying temperature is 55-75°C.

[0022] As a further preferred scheme, in the surface metallization process described in the embodiment of the present application, during the activation treatment, the activation solution includes 0.5-1.5 g / L palladium chloride, 70-85 g / L stannous chloride and 200-300 mL / L hydrochloric acid; the activation time is 3-5 minutes.

[0023] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, the first metal conductor layer is formed by one or a combination of two or more of chemical plating, electroplating, vacuum evaporation, and magnetron sputtering.

[0024] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, when forming the second metal conductor layer, one of chemical plating, electroplating, vacuum evaporation, and magnetron sputtering is adopted.

[0025] As a further preferred solution, the surface metallization process described in the embodiment of the present application further includes forming a third metal conductor layer on the surface of the first metal conductor layer.

[0026] As a further preferred solution, the surface metallization process described in the embodiment of the present application also includes the step of forming a welding layer on the surface of the metal second metal conductor layer: forming a Sn layer on the surface of the metal second metal conductor layer by electroplating or magnetron sputtering.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The shielding shell for the assembled dielectric filter described in the present application uses different metal materials to make the metal conductor layer, and can flexibly select the most suitable metal material according to actual needs (such as conductivity, corrosion resistance, cost and other factors), thereby optimizing costs while ensuring performance.

[0029] 2. Between the two metal conductor layers formed after the surface activation of the plastic substrate of the shielding shell for the assembled dielectric filter described in the present application, a diffusion layer with a thickness of 50-100nm is formed due to the mutual penetration of metal atoms, which greatly enhances the bonding force between the two metal conductor layers, avoids the delamination or falling off problems caused by different materials, and improves the overall stability and durability of the shielding shell.

[0030] 3. In the shielding shell for the assembled dielectric filter described in the present application, the use of a combination of different metal materials can bring about better conductivity and / or reflection performance, thereby better suppressing the leakage and interference of electromagnetic waves, which is crucial to improving the performance and stability of the dielectric filter.

[0031] 4. The shielding shell for the assembled dielectric filter described in the present application is based on a plastic substrate. While maintaining the excellent performance of the metal layer, the shielding shell also inherits the good processability and formability of the plastic material, making it easier for the shielding shell to adapt to various complex shapes and design requirements, reducing processing difficulty and cost.

[0032] 5. Although the shielding shell for the assembled dielectric filter described in the present application uses a variety of metal materials, by combining a reasonable metal plating process, it is possible to achieve effective cost control while ensuring performance; in addition, due to the use of a plastic substrate, compared with a shielding shell with an all-metal structure, this solution may have more advantages in terms of weight and cost.

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a schematic structural diagram of the shielding shell for the dielectric filter assembly described in Example 1 of the present application.

[0036] Figure 2 This is a schematic structural diagram of the shielding shell for the dielectric filter assembly described in Example 2 of the present application.

[0037] Figure 3 This is a schematic structural diagram of the shielding shell for the dielectric filter assembly described in Example 4 of the present application.

[0038] Figure 4 This is a schematic structural diagram of the shielding shell for the assembled dielectric filter described in Example 5 of the present application.

[0039] Figure 5 This is a waveform diagram actually measured for the shielding shell for the dielectric filter assembly described in this application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] The term "comprising" and other equivalent descriptions involved in the specification and claims of this application are intended to cover non-exclusive inclusions, including both the contents clearly described in the specification and claims, and the steps or units that are not described in the specification and claims but are inherent in the product, method or structure.

[0042] The embodiment of the present application provides a shielding shell for an assembly dielectric filter, comprising a plastic substrate and at least two metal conductor layers, wherein the metal conductor layers at least include a first metal conductor layer and a second metal conductor layer, wherein the first metal conductor layer and the second metal conductor layer are made of different metal materials, and since the metal materials used by the first metal conductor layer and the second metal conductor layer are different, a diffusion layer in which metal atoms mutually penetrate each other will be formed between the first metal conductor layer and the second metal conductor layer. In some embodiments, the material of the first metal conductor layer is Ni or Pd, and the material of the second metal conductor layer is one of Ni, Pd, and a nickel-copper alloy; for example, in some embodiments, the first metal conductor layer selects Pd as the conductor material, and the second metal conductor layer selects Ni as the conductor material, and after the first metal conductor layer is formed, a second metal conductor layer is formed on its surface, and there is a metal atom penetration layer of Pd and Ni between the metal Pd and the metal Ni to form a diffusion layer, and the existence of the diffusion layer can enhance the adhesion and overall strength between the first metal conductive layer and the second metal conductive layer, and the atomic arrangement in the diffusion layer is different from that of a single metal layer, and this structural difference can make the conductor layer have higher hardness, wear resistance, corrosion resistance or better conductivity, etc. When subjected to external force, the diffusion layer can play a certain buffering role, reduce the stress concentration between the two conductor layers, and thus extend the service life of the shielding shell. The thickness of the diffusion layer will affect the stability and reliability of the overall structure. The thickness of the diffusion layer affects the hardness of the conductor layer. As the thickness of the diffusion layer increases, the hardness of the conductor layer will also increase accordingly, which helps to enhance the wear resistance of the coating and extend its service life. However, an overly thick diffusion layer may increase brittleness and reduce the overall toughness. The diffusion layer also has a significant effect on the corrosion resistance of the conductor layer. The diffusion layer can form a dense protective layer to improve the overall corrosion resistance. Due to changes in the atomic arrangement and chemical composition in the diffusion layer, the conductivity of the conductor layer will change. The main manifestation is that when the diffusion layer is thin and uniform, the effect on the conductivity is small; but if the diffusion layer is too thick or has defects, the conductivity will decrease. In an embodiment of the present application, the thickness of the diffusion layer is 50-100nm.

[0043] In an embodiment of the present application, the first metal conductor layer is located on the surface of the plastic substrate. The thickness of the first metal conductor layer is crucial to the bonding and adhesion between the first metal conductor layer and the plastic substrate. The appropriate thickness can provide stronger bonding and adhesion, ensure a firm connection between the metal layer and the plastic substrate, and help prevent the metal layer from falling off or being damaged due to vibration, temperature changes or mechanical stress during use. The thickness of the first metal conductor layer will also affect its electrical conductivity. Thicker metal layers generally have lower resistance, thereby providing better current conduction capabilities. The first metal conductor layer serves as the initial barrier of the shielding shell, and its thickness has a direct impact on the reflection and absorption capabilities of electromagnetic waves. A metal layer of appropriate thickness can more effectively reflect and absorb electromagnetic waves, thereby improving shielding effectiveness. In the absence of a welding layer, the second metal conductor layer is usually located on the outer layer of the shielding shell. During use, the shielding shell may be subjected to physical damage such as friction and wear; a thicker second metal conductor layer can provide better wear resistance and extend the service life of the shielding shell. Although the first metal conductor layer has provided a certain electromagnetic shielding effect, the thickness of the second metal conductor layer can further enhance this effect, especially in the shielding of high-frequency electromagnetic waves, a thicker metal layer can more effectively absorb and dissipate electromagnetic waves. In addition, the thickness of the second metal conductor layer will also affect the appearance and texture of the shielding shell. Because too thick a metal layer will increase the cost, weight and processing difficulty, while too thin a metal layer may not meet the requirements of electromagnetic shielding, corrosion resistance and wear resistance. Therefore, in order to obtain the best shielding shell performance, in some embodiments of the present application, the relationship between the thickness d1 of the first metal conductor layer and the thickness d2 of the second metal conductor layer is: d2 = Rd1, R is any number between 2-9. In a specific scheme, the thickness of the first metal conductor layer is 0.4-1.0 μm, and the preferred thickness of the first metal conductor layer is 0.5-0.8 μm. The thickness of the second metal conductor layer is 2.0-4.0 μm, and preferably, the thickness of the second metal conductor layer is 2.5-3.0 μm.

[0044] As a further preferred solution, a third metal conductor layer is provided between the first metal conductor layer and the third metal conductor layer described in the embodiment of the present application, and a diffusion layer of metal atoms mutually permeating exists between the third metal conductor layer and the first metal conductor layer and the second metal conductor layer. The third metal conductor layer is located between the first metal conductor layer and the second metal conductor layer, which further enhances the electromagnetic shielding effectiveness, and its thickness has a direct impact on the reflection and absorption capacity of electromagnetic waves; the thickness of the third metal conductor layer is within a suitable range, which can effectively reflect and absorb electromagnetic waves, thereby improving the overall shielding effectiveness of the shielding shell. Since the first metal conductor layer and the second metal conductor layer may be made of different metal materials, there may be differences in their physical properties such as thermal expansion coefficient and conductivity. The presence of the third metal conductor layer can reduce the stress concentration and deformation caused by these differences, thereby improving the overall stability and reliability of the shielding shell, and playing a transition and buffering role. In addition, a thicker third metal conductor layer can provide better protection to prevent the shielding shell from being corroded by corrosive media. In some embodiments, the thickness of the third metal conductor layer is set to 2.0-4.0 μm.

[0045] As a further preferred solution, a metal welding layer is also provided on the surface of the second metal conductor layer described in the embodiment of the present application. The presence of the metal welding layer significantly improves the welding strength between the shielding shell and other components. Although the main function of the metal welding layer is to improve the welding performance, it will also have a certain impact on the electromagnetic shielding effect; and the metal welding layer usually has a high corrosion resistance, which can protect the shielding shell from the erosion of the corrosive medium. The metal welding layer can also serve as a wear-resistant layer to reduce the degree of wear on the surface of the shielding shell, thereby improving its durability. A thicker metal welding layer can provide better fusion effect and higher welding strength, ensuring that the shielding shell will not crack or deform due to stress concentration during the welding process; within an appropriate thickness range, the metal welding layer can also serve as an additional shielding layer to further reflect and absorb electromagnetic waves, thereby improving the overall shielding effectiveness of the shielding shell. In the embodiment of the present application, considering the influence of the thickness of the metal welding layer on the welding performance, electromagnetic shielding effectiveness, corrosion resistance and wear resistance, the thickness of the metal welding layer is 3.0 to 6.0 μm. Preferably, the thickness of the metal welding layer is 4.0-5.0 μm.

[0046] As a further preferred solution, the plastic substrate described in the embodiment of the present application is selected from polyetherimide (PEI) or polyphenylene sulfide (PPS). In the embodiment of the present application, polyetherimide (PEI) or polyphenylene sulfide (PPS) is selected as the plastic substrate of the shielding shell of the assembled dielectric filter, which has advantages that other plastics cannot match. Among them, the excellent performance of polyetherimide (PEI) is mainly manifested as follows: First, polyetherimide (PEI) has high and long-term heat resistance and good high-temperature stability. At high temperatures, PEI can maintain high strength, high rigidity, wear resistance and dimensional stability; second, PEI has excellent dimensional stability, which is crucial for filter shielding shells that require precise docking and long-term stability; third, PEI has outstanding electrical properties, with stable dielectric constants and dielectric losses and extremely high dielectric strength over a wide frequency and temperature range; fourth, PEI is resistant to chemicals and radiation. PEI has a wide range of chemical resistance, including resistance to most hydrocarbons, alcohols and all halogenated solvents, as well as resistance to inorganic acids and short-term weak alkalis, and has good resistance to ultraviolet rays and gamma rays; therefore, these excellent properties of PEI give it a unique advantage in the field of 5G communications, and it is particularly suitable for RF connectors, filters and other components. The excellent performance of polyphenylene sulfide (PPS) is mainly manifested in: First, PPS is used under high temperature and high humidity conditions and also shows excellent dimensional stability. It is an ideal material for producing complex parts with very strict tolerances; Second, PPS has excellent electrical insulation properties and can still maintain high volume resistivity and insulation resistance after being exposed to a high humidity environment; Third, PPS has high thermal performance and flame retardant properties, and is a high-temperature resistant special polymer without the need to add flame retardants; Fourth, PPS has high strength, high rigidity and low degradation characteristics even under high temperature conditions, and also shows excellent fatigue resistance and creep resistance; In addition, PPS has good chemical resistance. Therefore, polyetherimide (PEI) and polyphenylene sulfide (PPS) are ideal materials selected by the embodiments of this application to become the clinker substrate of the high-performance filter shielding shell. In the research of this application, it was found that the thickness setting of the plastic substrate is an important design parameter and the main factor affecting the performance of the shielding shell. The thickness of the plastic substrate determines the thickness of the shielding shell, and there is a positive correlation between the thickness of the shielding shell and its shielding effectiveness; on the one hand, a thicker shielding shell can provide a better physical barrier, reduce the penetration and leakage of electromagnetic waves, and its shielding effect on electromagnetic waves is better; on the other hand, a thicker shielding shell usually has a higher mechanical strength and can better resist external shocks and vibrations, thereby protecting the internal dielectric filter from damage; thirdly, a thicker shielding shell can provide better thermal stability, which helps prevent the influence of high temperature on the plastic substrate and the internal filter. However, in the actual product of this application, the thickness of the plastic substrate is not the thicker the better, and an overly thick shielding shell will affect the heat dissipation of the filter.Therefore, in order to ensure that the shielding shell has good mechanical strength, thermal stability and economy while meeting the shielding requirements, in the embodiment of the present application, the thickness of the plastic substrate is set to 5-10mm. Within this thickness range, the plastic substrate can provide a sufficient physical barrier to effectively block and reduce the penetration and leakage of electromagnetic waves, while having high mechanical strength, being able to resist external shock and vibration, and having good heat dissipation performance, and keeping weight and cost under control. Preferably, the thickness of the plastic substrate is 6-9mm.

[0047] The present application also provides a surface metallization process for a shielding shell for an assembly dielectric filter, comprising:

[0048] Pretreatment: Clean the surface of the plastic substrate to remove oil, dust and other impurities on the surface. After cleaning, perform roughening treatment to increase the surface roughness.

[0049] Sensitization treatment: the pre-treated plastic substrate is immersed in the sensitizing solution, so that the surface of the plastic substrate fully absorbs the metal ions in the sensitizing solution, and then it is taken out and rinsed to remove the residual sensitizing solution on the surface, and a sensitized layer is formed after drying;

[0050] Activation treatment: After the sensitized layer is formed, the plastic substrate is immersed in the activation solution to reduce the metal ions in the sensitized layer to metal atoms and form metal catalytic centers;

[0051] Forming a first metal conductor layer: forming a first metal conductor layer on the surface of the activated plastic substrate;

[0052] Forming a second metal conductor layer: forming a second metal conductor layer on the surface of the first metal conductor layer.

[0053] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, in the pretreatment step, the surface of the plastic substrate is cleaned with alkaline solution, and the treatment method can be ultrasonic cleaning or high-pressure water gun cleaning to ensure that the oil, dust and other impurities on the surface of the plastic substrate are completely removed; during the roughening process, the surface of the plastic substrate is roughened by sandpaper polishing or sandblasting, and can also be roughened by chemical etching and other methods to increase the roughness of the surface of the plastic substrate and improve the adhesion of the subsequent metal layer. After the roughening treatment, the roughness is controlled to 0.5-1.0μm, that is, a small depression of 0.5-1.0μm is formed on the surface of the plastic substrate.

[0054] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, the sensitization treatment is to form a conductive layer on the surface of the plastic substrate, so that the originally non-conductive plastic substrate surface has conductivity, which provides the necessary conditions for the subsequent metallization treatment. The sensitization layer, as the core of the initial reaction, can promote the start of the electroplating reaction and is conducive to the formation of the first metal conductive layer; after the sensitization treatment, a very strong chemical bond structure can be formed on the plastic surface, which helps to reduce the peeling rate between the plastic part and the electroplating layer, thereby improving the firmness of the electroplating layer. In some embodiments of the present application, during the sensitization treatment, the sensitizing solution includes 45-55g / L of stannous chloride, 10-15mL / L of hydrochloric acid and 5-8g / L of tin particles. In the embodiments of the present application, during the sensitization treatment, the temperature has an impact on the formation of the sensitized layer and the subsequent formation of the metal conductor layer. The impact is manifested as: treatment time and drying. If the sensitization treatment time is too short, the plastic surface may not be fully sensitized, the sensitized layer may be uneven or the thickness may be insufficient; if the sensitization treatment time is too long, the sensitized layer may be too thick, and may even cause the sensitizing solution to overreact and produce unnecessary by-products. Improper sensitization treatment time may weaken the bonding force between the electroplating layer and the plastic substrate, and the electroplating layer may easily peel off or crack. Therefore, setting a reasonable sensitization treatment time to form a uniform and dense sensitized layer is conducive to the uniform deposition of metal ions in the electroplating solution on the plastic surface, thereby obtaining a good quality electroplating layer. In some embodiments of the present application, the sensitization treatment time is set to 20-30 minutes. In the drying process of forming the sensitized layer, if the drying temperature is too low, the moisture in the sensitized layer will not be fully removed, affecting the stability of the sensitized layer. If the drying temperature is too high, the sensitized layer will be thermally decomposed or oxidized, reducing its catalytic activity. These will weaken the bonding force between the sensitized layer and the plastic substrate, thereby affecting the bonding force between the electroplating layer and the plastic substrate. Therefore, in order to ensure the formation of a good chemical bond between the sensitized layer and the plastic substrate, improve the bonding force between the electroplating layer and the plastic substrate, and consider the characteristics of the plastic substrate, in some embodiments of the present application, the drying temperature after sensitization is set to 55-75°C. Preferably, the drying temperature is 60-65°C.

[0055] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, activation treatment is a necessary step before chemical plating, the purpose of which is to obtain a catalytic metal surface to start and maintain the electroplating reaction. After the plastic substrate surface is activated, metal ions or metal particles with catalytic activity can be introduced. These active substances can serve as the starting point of the electroplating reaction, so that the metal ions in the electroplating solution can be reduced to metal atoms and deposited on the plastic surface. Through the activation treatment, some polar groups or functional groups can be formed on the plastic surface, and these groups can form chemical bonds with the metal atoms in the metal coating, thereby enhancing the bonding force between the metal coating and the plastic substrate; the activation treatment can change the microstructure of the plastic surface, forming a more uniform and rough surface morphology, which is conducive to the uniform distribution of metal ions in the electroplating solution on the plastic surface, and promotes the deposition and growth of metal atoms; therefore, the plastic substrate that has been activated can obtain a more uniform and dense electroplating layer after electroplating. In some embodiments of the present application, during the activation treatment, the activation solution includes 0.5-1.5 g / L palladium chloride, 70-85 g / L stannous chloride and 200-300 mL / L hydrochloric acid; and the activation time is 3-5 minutes.

[0056] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, the first metal conductor layer is formed by one or a combination of two or more of chemical plating, electroplating, vacuum evaporation, and magnetron sputtering.

[0057] As a further preferred solution, in the surface metallization process described in the embodiment of the present application, when forming the third metal conductor layer, one of chemical plating, electroplating, vacuum evaporation, and magnetron sputtering is adopted.

[0058] In the embodiments of the present application, the metal conductor layer formed by plating palladium, nickel, silver, copper and other materials is usually electroless plating. The specific process parameters of the electroless plating are shown in Table 1 below.

[0059] Table 1: Parameters of chemical plating

[0060]

[0061] In some embodiments, some metal conductor layers may also be formed by electroplating. The specific parameter conditions of the electroplating are shown in Table 2.

[0062] Table 2 Electroplating parameters

[0063]

[0064] In some embodiments, some metal conductor layers may also be deposited by vacuum evaporation. The conditions for vacuum evaporation include: air pressure <3×10 -2Pa, energy is 0.1-1eV, deposition rate is 0.1-10um / min. When magnetron sputtering is used, the sputtering chamber temperature is 150-400℃, pressure is <1Pa, power is 50-200W, and sputtering time is 10min-2h.

[0065] As a further preferred solution, the surface metallization process described in the embodiment of the present application also includes forming a second metal conductor layer on the surface of the first metal conductor layer by combining chemical plating with electroplating.

[0066] As a further preferred scheme, the surface metallization process described in the embodiment of the present application also includes the step of forming a metal welding layer on the surface of the metal third metal conductor layer: forming a Sn layer on the surface of the metal third metal conductor layer by electroplating or magnetron sputtering.

[0067] In order to further explain the present application, specific examples of the present application are provided below.

[0068] Example 1

[0069] like Figure 1 As shown, this embodiment provides a shielding shell for an assembled dielectric filter, comprising a plastic substrate 10, the plastic substrate 10 is made of PEI (polyetherimide) and has a thickness of 6.0 mm; and

[0070] The first metal conductor layer 20 is made of Pd and has a thickness of 0.6 μm;

[0071] The second metal conductor layer 30 is made of Ni and has a thickness of 3.0 μm;

[0072] Between the first metal conductor layer 20 and the second metal conductor layer 30 is a diffusion layer where metal Pd and metal Ni atoms interpenetrate each other, and the average thickness of the diffusion layer is 76 nm;

[0073] The metal welding layer 40 is made of Sn and has a thickness of 5.0 μm;

[0074] The first metal conductor layer, the second metal conductor layer and the metal welding layer are all formed by magnetron sputtering.

[0075] The surface metallization process of the shielding shell for the dielectric filter assembly comprises the following steps:

[0076] Pretreatment: Use a high-pressure water gun to clean the surface of the plastic substrate to remove oil, dust and other impurities on the surface. After cleaning, use sandpaper to roughen the surface to increase the surface roughness. The roughness is controlled to 0.5-1.0μm;

[0077] Sensitization treatment: the pretreated plastic substrate is immersed in a sensitizing solution, which includes 45g / L stannous chloride, 10mL / L hydrochloric acid and 8g / L tin particles, and the rest is pure water. The treatment time is 20 minutes, so that the surface of the plastic substrate can fully absorb the metal ions in the sensitizing solution. After taking it out, rinse it clean to remove the residual sensitizing solution on the surface, and dry it at 60°C to form a sensitized layer;

[0078] Activation treatment: After forming the sensitized layer, the plastic substrate is immersed in an activation solution for 3 minutes. The activation solution includes 0.5g / L palladium chloride, 85g / L stannous chloride and 200mL / L hydrochloric acid, so that the metal ions in the sensitized layer are reduced to metal atoms and form metal catalytic centers.

[0079] Forming a first metal conductor layer: forming the first metal conductor layer on the surface of the activated plastic substrate by magnetron sputtering, the conditions of magnetron sputtering are: sputtering chamber temperature is 300°C, pressure is <1Pa, power is 100W, and sputtering time is 30min;

[0080] Forming a second metal conductor layer: forming the second metal conductor layer on the surface of the first metal conductor layer by magnetron sputtering, the conditions of magnetron sputtering are: sputtering chamber temperature is 150° C., pressure is <1 Pa, power is 100 W, and sputtering time is 1 hour;

[0081] Forming a metal welding layer: Sn is plated on the surface of the second metal conductor layer by magnetron sputtering to form a metal welding layer. The conditions of magnetron sputtering are as follows: the sputtering chamber temperature is 150°C, the pressure is <1Pa, the power is 50W, and the sputtering time is 1h.

[0082] After testing with a network analyzer, the assembled dielectric filter product made of the plastic shielding shell described in Example 1, compared with the existing metal structure shielding shell dielectric filter, not only has the same high suppression and high reliability characteristics of 71dB@3Ghz, but also has a weight reduction of 48.2% and a raw material cost reduction of 55%.

[0083] Example 2

[0084] like Figure 2 As shown, this embodiment provides a shielding shell for an assembly dielectric filter, including a plastic substrate 10, the plastic substrate 10 is made of PEI (polyetherimide) and has a thickness of 6.0 mm;

[0085] The first metal conductor layer 20 is made of Pd and has a thickness of 0.5 μm;

[0086] The second metal conductor layer 30 is made of Ni and has a thickness of 2.5 μm;

[0087] The third metal conductor layer 50 is made of Ag and has a thickness of 2.1 μm;

[0088] The third metal conductor layer is located between the first metal conductor layer and the second metal conductor layer. The diffusion layer between the third metal conductor layer and the first metal conductor layer is formed by the mutual penetration of metal Pd atoms and metal Ag atoms, and has an average thickness of 54 nm. The diffusion layer between the third metal conductor layer and the second metal conductor layer is formed by the mutual penetration of metal Ni atoms and metal Ag atoms, and has an average thickness of 69 nm.

[0089] The metal welding layer 40 is made of Sn and has a thickness of 4.3 μm;

[0090] The surface metallization process of the shielding shell for the dielectric filter assembly comprises the following steps:

[0091] Pretreatment: Use a high-pressure water gun to clean the surface of the plastic substrate to remove oil, dust and other impurities on the surface. After cleaning, use sandpaper to roughen the surface to increase the surface roughness. The roughness is controlled to 0.5-1.0μm;

[0092] Sensitization treatment: the pretreated plastic substrate is immersed in a sensitizing solution, which includes 55g / L stannous chloride, 15mL / L hydrochloric acid and 5g / L tin particles, and the rest is pure water. The treatment time is 30 minutes, so that the surface of the plastic substrate can fully absorb the metal ions in the sensitizing solution. After taking it out, rinse it clean to remove the residual sensitizing solution on the surface, and dry it at 55℃ to form a sensitized layer;

[0093] Activation treatment: After forming the sensitized layer, the plastic substrate is immersed in an activation solution for 3 minutes. The activation solution includes 1.5g / L palladium chloride, 70g / L stannous chloride and 300mL / L hydrochloric acid, so that the metal ions in the sensitized layer are reduced to metal atoms and form metal catalytic centers.

[0094] Forming a first metal conductor layer: using chemical plating to plate Pd on the surface of the activated plastic substrate to form the first metal conductor layer, the chemical plating conditions are: the chemical plating solution includes palladium chloride, the concentration is 5g / L, sodium hypophosphite, the concentration is 10g / L, the time is 30min, and the temperature is 35°C;

[0095] Forming the third metal conductor layer: Ag is plated on the surface of the first metal conductor layer by electroplating to form the third metal conductor layer. The electroplating conditions are: the electroplating solution is silver nitrate, the concentration is 20g / L; sodium thiosulfate, the concentration is 120g / L, and the current density is 1.0A / dm 2 , the plating temperature is 30℃

[0096] Forming the second metal conductor layer: Ni is plated on the surface of the third metal conductor layer by chemical plating to form the second metal conductor layer. The conditions of chemical plating are: the chemical plating solution includes nickel sulfate, the concentration is 20g / L; sodium hypophosphite, the concentration is 10g / L; the time is 10min, and the temperature is 30°C.

[0097] Forming a metal welding layer: Sn is plated on the surface of the second metal conductor layer by electroplating to form a metal welding layer. The electroplating conditions are: the electroplating solution is tin chloride, the concentration is 70g / l, and the current density is 10A / dm 2 , the electroplating temperature is 40-60℃.

[0098] According to the network analyzer test, the assembled dielectric filter product made of the plastic shielding shell of the present invention not only has the same high suppression of 75dB@3Ghz and high reliability as the existing metal structure shielding shell dielectric filter, but also has a weight reduction of 48.2% and a raw material cost reduction of 58%.

[0099] Example 3

[0100] This embodiment provides a shielding shell for an assembly dielectric filter, comprising a plastic substrate, the plastic substrate is made of PPS (polyphenylene sulfide) and has a thickness of 6.0 mm;

[0101] The first metal conductor layer is made of Pd and has a thickness of 0.4 μm;

[0102] The second metal conductor layer is made of Ni and has a thickness of 2.5 μm;

[0103] The third metal conductor layer is made of Ag and has a thickness of 3.0 μm;

[0104] The third metal conductor layer is located between the first metal conductor layer and the second metal conductor layer. The diffusion layer between the third metal conductor layer and the first metal conductor layer is formed by the mutual penetration of metal Pd atoms and metal Ag atoms, and has an average thickness of 54nm; the diffusion layer between the third metal conductor layer and the second metal conductor layer is formed by the mutual penetration of metal Ni atoms and metal Ag atoms, and has an average thickness of 69nm.

[0105] In the surface metallization process of the shielding shell for the assembly dielectric filter, the method of the above-mentioned embodiment 2 is followed, except that when forming the third metal conductor layer, the chemical plating time is 5 minutes, and the chemical plating solution includes silver cyanide with a concentration of 2.0 g / L; ammonium sulfate with a concentration of 1.0 g / L; and the temperature is 20°C; the second metal conductor layer is also chemically plated, and the chemical plating conditions are: the chemical plating solution is nickel sulfate with a concentration of 20 g / L; sodium hypophosphite with a concentration of 5 g / L; the time is 5 minutes, and the temperature is 25°C.

[0106] After testing, the assembled dielectric filter product made of the plastic shielding shell of the present invention not only has the same high suppression and high reliability characteristics as the existing metal structure shielding shell dielectric filter, but also has a weight reduction of 46.4% and a raw material cost reduction of 53%.

[0107] Example 4

[0108] like Figure 3 As shown, this embodiment provides a shielding shell for an assembled dielectric filter, comprising a plastic substrate 10, the plastic substrate 10 is made of PEI (polyetherimide) and has a thickness of 7.0 mm; and

[0109] The first metal conductor layer 20 is made of Pd and has a thickness of 0.8 μm;

[0110] The second metal conductor layer 30 is made of Ni and has a thickness of 4.0 μm;

[0111] Between the first metal conductor layer and the second metal conductor layer is a diffusion layer in which metal Pd and metal Ni atoms mutually penetrate each other, and the average thickness of the diffusion layer is 81 nm.

[0112] The first metal conductor layer and the second metal conductor layer are both deposited by vacuum evaporation, and the specific steps are as follows:

[0113] Vacuum evaporation of Pd forms the first metal conductor layer on the surface of the plastic substrate. The vacuum evaporation conditions are: pressure <3×10 -2 Pa, the energy is 0.5 eV, and the deposition rate is 0.2 μm / min.

[0114] Ni is vacuum-deposited on the surface of the first metal conductor layer to form a second metal conductor layer. The vacuum deposition conditions are: gas pressure <3×10 -2 Pa, energy is 0.5eV, and deposition rate is 1.0μm / min.

[0115] The other steps were carried out according to the above-mentioned Example 1.

[0116] After testing, the assembled dielectric filter product made of the plastic shielding shell of the present invention not only has the same high suppression and high reliability characteristics as the existing metal structure shielding shell dielectric filter, but also has a weight reduction of 48.2% and a raw material cost reduction of 56%.

[0117] Example 5

[0118] like Figure 4 As shown, this embodiment provides a shielding shell for an assembly dielectric filter, including a plastic substrate 10, the plastic substrate 10 is made of PEI (polyetherimide) and has a thickness of 6.0 mm;

[0119] The first metal conductor layer 20 is made of Ni and has a thickness of 0.9 μm;

[0120] The second metal conductor layer 30 is made of nickel-copper alloy and has a thickness of 2.5 μm;

[0121] The third metal conductor layer 50 is made of Cu and has a thickness of 2.0 μm;

[0122] The third metal conductor layer is located between the first metal conductor layer and the second metal conductor layer, and the diffusion layers between the third metal conductor layer and the first metal conductor layer and between the third metal conductor layer and the second metal conductor layer are mutually permeated between metal Ni atoms and metal Cu atoms, and the average thickness is 69 nm;

[0123] The metal welding layer is made of Sn and has a thickness of 5.5μm.

[0124] The first metal conductor layer and the second metal conductor layer are plated by chemical plating method, as follows:

[0125] The first metal conductor layer is formed by chemical plating Ni, and the chemical plating conditions are as follows: the chemical plating solution includes nickel sulfate, the concentration is 40g / L; sodium hypophosphite, the concentration is 20g / L; the time is 10min, and the temperature is 40°C;

[0126] The second metal conductor layer is formed by chemically plating nickel-copper alloy, and the chemical plating conditions are as follows: the chemical plating solution includes nickel sulfate, concentration 40g / L; copper sulfate, concentration 90g / L; sodium hypophosphite, concentration 2-20g / L; the time is 30min, and the temperature is 40°C;

[0127] Electroplating Cu to form the third metal conductor layer, the electroplating conditions are: the electroplating solution is copper sulfate, the concentration is 100g / L, sulfuric acid is 50g / L, the current density is 30A / dm 2 , the electroplating temperature is 55℃;

[0128] Electroplating Sn to form a metal welding layer, the electroplating solution is tin chloride, the concentration is 50g / L, and the current density is 5A / dm 2 , the electroplating temperature is 45℃;

[0129] The other steps and parameters are the same as those in Example 2.

[0130] After testing, the assembled dielectric filter product made of the plastic shielding shell of the present invention not only has the same high suppression and high reliability characteristics as the existing metal structure shielding shell dielectric filter, but also has a 46.4% reduction in weight and a 52% reduction in raw material cost.

[0131] Example 6

[0132] This embodiment provides a shielding shell for an assembly dielectric filter, comprising a plastic substrate, the plastic substrate is made of PPS (polyphenylene sulfide) and has a thickness of 7.0 mm; and

[0133] The first metal conductor layer is made of Pd and has a thickness of 0.5 μm;

[0134] The second metal conductor layer is made of nickel-copper alloy and has a thickness of 3.0 μm;

[0135] Between the first metal conductor layer and the second metal conductor layer is a diffusion layer where metal Pd, metal Ni and Cu atoms interpenetrate each other, and the average thickness of the diffusion layer is 72 nm;

[0136] The metal welding layer is made of Sn and has a thickness of 5.0 μm.

[0137] The first metal conductor layer, the second metal conductor layer and the metal welding layer are all formed by a magnetron sputtering method. Except for the second metal conductor layer, other steps and parameters are the same as those in Example 1. The steps for forming the second metal conductor layer are as follows:

[0138] The second metal conductor layer is formed on the surface of the first metal conductor layer by magnetron sputtering of nickel-copper alloy. The conditions of magnetron sputtering are as follows: the sputtering chamber temperature is 25°C, the pressure is <1Pa, the power is 50W, and the sputtering time is 10min.

[0139] After testing, the assembled dielectric filter product made of the plastic shielding shell of the present invention not only has the same high suppression and high reliability characteristics as the existing metal structure shielding shell dielectric filter, but also has a 46.4% reduction in weight and a 50% reduction in raw material cost.

[0140] The performance of the shielding case for the assembled dielectric filter obtained in the above-mentioned Examples 1 to 6 was tested. See Table 1 for the test items and results.

[0141] Table 1: Performance test results of shielding case for assembled dielectric filter

[0142]

[0143] Figure 5 This is a waveform diagram actually measured for the shielding shell for the dielectric filter assembly described in the embodiment of the present application. Figure 5 The vertical axis represents the suppression effect of the filter outside the passband. The results show that by assembling dielectric filters, the out-of-band suppression effect can reach more than 85dB.

[0144] The above-mentioned implementation mode provided in the embodiment of the present application is only a preferred implementation mode of the present invention, and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technical personnel in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A shielding case for an assembled dielectric filter, characterized in that: It comprises a plastic substrate and at least two metal conductor layers, wherein the two metal conductor layers are made of different metal materials, a diffusion layer for mutual penetration of metal atoms is formed between the two metal conductor layers, and the average thickness of the diffusion layer is 50-100nm.

2. The shield case for an assembled dielectric filter according to claim 1, wherein: The metal conductor layer comprises a first metal conductor layer and a second metal conductor layer. The first metal conductor layer and the second metal conductor layer are made of different metal materials. Metal atoms of the first metal conductor layer and the second metal conductor layer penetrate each other to form a diffusion layer.

3. The shield case for an assembled dielectric filter according to claim 2, wherein: A third metal conductor layer is arranged between the first metal conductor layer and the second metal conductor layer. A diffusion layer for mutual penetration of metal atoms exists between the third metal conductor layer and the first metal conductor layer and the second metal conductor layer. The thickness of the third metal conductor layer is 2.0-4.0 μm.

4. The shield case for an assembled dielectric filter according to claim 3, characterized in that: A metal welding layer is also provided on the surface of the second metal conductor layer, and the thickness of the metal welding layer is 3.0-6.0 μm.

5. The shield case for a dielectric filter assembly according to claim 2, wherein: The plastic substrate is polyetherimide or polyphenylene sulfide.

6. The shield case for an assembled dielectric filter according to claim 2, wherein: The material of the first metal conductor layer is Ni or Pd, and the thickness of the first metal conductor layer is 0.4-1.0 μm.

7. The shield case for an assembled dielectric filter according to claim 6, characterized in that: The material of the second metal conductor layer is one of Ni, Pd and nickel-copper alloy; the thickness of the second metal conductor layer is 2.0-4.0 μm.

8. A surface metallization process for a shielding shell for an assembled dielectric filter as claimed in any one of claims 1 to 7, characterized in that: include Pretreatment: Clean the surface of the plastic substrate to remove oil, dust and other impurities on the surface. After cleaning, perform roughening treatment to increase the surface roughness. Sensitization treatment: the pre-treated plastic substrate is immersed in the sensitizing solution, so that the surface of the plastic substrate fully absorbs the metal ions in the sensitizing solution, and then it is taken out and rinsed to remove the residual sensitizing solution on the surface, and a sensitized layer is formed after drying; Activation treatment: After the sensitized layer is formed, the plastic substrate is immersed in the activation solution to reduce the metal ions in the sensitized layer to metal atoms and form metal catalytic centers; Forming a first metal conductor layer: forming a first metal conductor layer on the surface of the activated plastic substrate; Forming a second metal conductor layer: forming a second metal conductor layer on the surface of the first metal conductor layer.

9. The metallization process according to claim 8, characterized in that: In the pretreatment step, the surface of the plastic substrate is cleaned with an alkali solution, and the roughness of the surface of the plastic substrate is increased by sandpaper polishing or sandblasting.

10. The metallization process according to claim 8, characterized in that: During the sensitization treatment, the sensitizing solution includes 45-55 g / L of stannous chloride, 10-15 mL / L of hydrochloric acid and 5-8 g / L of tin particles; the treatment time is 20-30 minutes, and the drying temperature is 55-75°C.

11. The metallization process according to claim 8, characterized in that: During the activation treatment, the activation solution includes 0.5-1.5 g / L palladium chloride, 70-85 g / L stannous chloride and 200-300 mL / L hydrochloric acid; the activation time is 3-5 minutes.

12. The metallization process according to claim 8, characterized in that: The first metal conductor layer is formed by one or a combination of chemical plating, electroplating, vacuum evaporation, and magnetron sputtering.

13. The metallization process according to claim 12, characterized in that: When forming the third metal conductor layer, one of chemical plating, electroplating, vacuum evaporation and magnetron sputtering is adopted.

14. The metallization process according to claim 8, characterized in that: The method also includes forming a third metal conductor layer on the surface of the first metal conductor layer.

15. The metallization process according to claim 8, characterized in that: The method also includes the step of forming a metal welding layer on the surface of the second metal conductor layer: forming a Sn layer on the surface of the second metal conductor layer by electroplating or magnetron sputtering.

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