Injection molding packaging method of mobile phone camera module

Abstract

The invention relates to the technical field of packaging. The invention discloses an injection molding packaging method of a mobile phone camera module, which comprises the following steps: S1, preparing a camera module assembly comprising a circuit board, an image sensor and a lens, positioning the camera module assembly on a bearing surface, applying negative pressure through a negative pressure air hole communicated with the bearing surface, and adsorbing and fixing the assembly; s2, the injection mold is closed, electromagnetic shielding composite plastic is injected into the cavity for wrapping injection molding, and an integrated packaging structure body wrapping the circuit board and the sensor and keeping a lens light path is formed; and S3, negative pressure releasing and demolding are conducted after injection molding, deburring and cleaning are conducted on the packaging body, and then finish machining is conducted on the installation datum plane. By means of negative pressure fixing and integrated injection molding, efficient and high-sealing-performance packaging of the camera module is achieved. The multi-element electromagnetic shielding composite plastic is adopted, gradient metallization treatment is combined, so that the shielding effect is good, and the cable has excellent heat conductivity, low thermal expansion coefficient and high dimensional stability.

Description

Technical Field

[0001] This invention relates to the field of packaging technology, and in particular to an injection molding packaging method for a mobile phone camera module. Background Technology

[0002] As smartphones rapidly evolve towards thinner, lighter, and more integrated designs, camera modules are shrinking in size and becoming increasingly densely packed with internal electronic components. This makes them highly susceptible to electromagnetic interference from the motherboard, radio frequency modules, and other high-frequency circuits during operation. Such interference can not only cause image sensor signal distortion and increased noise, but in severe cases, it can also lead to blurred images or even malfunctions, significantly impacting the user experience. Therefore, achieving efficient electromagnetic shielding within limited space has become a critical issue that urgently needs to be addressed in mobile phone camera packaging technology.

[0003] Traditional camera modules often use metal brackets or conductive tape for partial shielding, followed by multi-step assembly and encapsulation. This method is not only cumbersome and costly, but also offers limited shielding effectiveness, failing to cover all frequency band interference, especially performing poorly in the 2-18GHz 5G and Wi-Fi high-frequency bands. Furthermore, the significant difference in thermal expansion coefficients between metal structures and plastic components makes them prone to gaps or delamination under temperature cycling or drop impacts, leading to decreased shielding performance or even failure. Simultaneously, traditional processes struggle to balance heat dissipation, sealing, and precision assembly requirements, failing to meet the stringent reliability and environmental adaptability standards of modern high-performance cameras.

[0004] In recent years, although some studies have attempted to incorporate conductive fillers into plastics for injection molding, problems such as unstable shielding effectiveness, deterioration of mechanical properties, or poor flowability have become increasingly common. Ensuring low internal stress, high dimensional accuracy, and good thermal conductivity in the integrated molding process remains a significant technical challenge for the industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses an innovative injection molding packaging method for mobile phone camera modules that effectively and synergistically addresses multiple requirements such as electromagnetic shielding, thermal management, structural strength, and manufacturing efficiency, achieving breakthroughs in performance and process.

[0006] This invention discloses an injection molding packaging method for a mobile phone camera module, which includes the following steps:

[0007] S1, Fixing and Preparation: Provide a camera module assembly including a circuit board, image sensor and lens, position it on the bearing surface, and apply negative pressure through negative pressure vents connected to the bearing surface to adsorb and fix the camera module assembly.

[0008] S2, Integrated Injection Molding: Close the injection mold, inject electromagnetic shielding composite plastic into the cavity, perform encapsulation injection molding, and form an integrated package structure that completely encapsulates the circuit board and image sensor, while leaving room for the lens optical path;

[0009] S3, Post-processing and reinforcement: After injection molding, the negative pressure is released and the mold is demolded. The encapsulated structure is deburred and cleaned, and the mounting reference surface is precision machined.

[0010] Furthermore, the composition of the electromagnetic shielding composite plastic includes:

[0011] Matrix resin: glass fiber reinforced PA66 or polyphenylene sulfide, accounting for 55%-70% by weight;

[0012] Electromagnetic shielding filler: accounting for 15%-30% by mass, comprising conductive polymers, nano-carbon materials, and two-dimensional transition metal carbonitrides, wherein the mass ratio of conductive polymers to nano-carbon materials is 5:1 to 1:1, and two-dimensional transition metal carbonitrides account for 5%-15% of the total filler mass;

[0013] Reinforcing particles: 15%-25% by mass, the reinforcing particles are a mixture of glass microspheres with a particle size of 5μm-20μm and short-cut carbon fibers with a length of 0.2mm-0.5mm in a mass ratio of 1:1 to 3:1;

[0014] Thermal conductivity regulating particles: 0.5%-8% by mass, which are particles of aluminum nitride and silicon dioxide in a mass ratio of 2:1 to 4:1;

[0015] Antioxidant: 0.2%-0.5% by weight of compound antioxidant;

[0016] The total mass percentage of all components is 100%.

[0017] Furthermore, the electromagnetic shielding filler also includes 3%-8% of the total mass of the electromagnetic shielding filler, which is multi-layer graphene-coated carbonyl iron powder, wherein the number of graphene coating layers is 3-8, the particle size of the carbonyl iron powder is 1-10μm, and the graphene coating process is carried out under ultrasonic assistance, with an ultrasonic power of 500-800W and a time of 1-3h.

[0018] Furthermore, the conductive polymer is at least one of polyaniline, polypyrrole, or poly(3,4-ethylenedioxythiophene), and the nanocarbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets, wherein the mass ratio of multi-walled carbon nanotubes to graphene nanosheets is 1:2 to 2:1, the aspect ratio of multi-walled carbon nanotubes is 50-200, and the particle size of graphene nanosheets is 5-20 μm.

[0019] Furthermore, the two-dimensional transition metal carbonitride is Ti3C2T XIts surface is modified with silane coupling agent KH-550 at a temperature of 80-100℃ for 30-60 minutes.

[0020] Furthermore, the electromagnetic shielding composite plastic has an electromagnetic interference shielding effectiveness of ≥45dB in the 2-18GHz frequency band, and a volume resistivity of ≤10Ω·cm, a thermal conductivity of ≥0.6W / (m·K), and a coefficient of thermal expansion of ≤25ppm / ℃.

[0021] Furthermore, after step S3, a gradient metallization process is performed on the outer surface of the packaged structure to construct a composite electromagnetic shielding layer.

[0022] Gradient metallization includes: first chemically plating copper with a thickness of 1-3 μm, and then vacuum magnetron sputtering nickel with a thickness of 1-5 μm to form a Cu / Ni double-layer structure, thereby improving the overall EMI shielding effectiveness to ≥58dB;

[0023] Before metal plating, the plastic substrate is first treated with a combination of ultraviolet light and ozone for 5-15 minutes.

[0024] Furthermore, the specific conditions for combined ultraviolet-ozone treatment are as follows:

[0025] Using dual-band ultraviolet light with wavelengths of 185nm and 254nm, at ozone concentrations of 50-100mg / m³ 3 The substrate of the encapsulation structure is surface activated for 5-15 minutes in an environment with a processing temperature of 40-60℃ and a relative humidity of 30%-50%.

[0026] Furthermore, the injection molding process parameters for step S2 are as follows:

[0027] Barrel temperature 235℃-265℃, nozzle temperature 245℃-275℃, mold temperature 90℃-125℃, injection pressure 85-125MPa, holding pressure 55-85MPa, holding time 6-18s, cooling time 25-45s; and a pulse holding pressure strategy is adopted during the injection process.

[0028] Furthermore, the preparation method of electromagnetic shielding composite plastic includes:

[0029] S2.1 All solid raw materials are vacuum dried at 80℃-100℃ for 4-6 hours, with the moisture content controlled to ≤0.05%;

[0030] S2.2 Pre-disperse the electromagnetic shielding filler in a high-speed mixer at a speed of 800-1200 r / min for 10-20 min;

[0031] S2.3 Add the matrix resin, reinforcing particles, thermal conductivity regulating particles and antioxidant, and continue mixing for 20-40 minutes;

[0032] S2.4 The mixture is fed into a twin-screw extruder for melt blending and granulation. The process parameters of the twin-screw extruder are: feeding section 180℃-200℃, melting section 230℃-250℃, homogenization section 240℃-260℃, die head temperature 235℃-255℃, and screw speed 300-500r / min.

[0033] The beneficial effects of this invention are:

[0034] This invention provides an injection molding packaging method for mobile phone camera modules, improving packaging efficiency and structural reliability through an integrated injection molding process. A negative pressure adsorption method is used to fix the module components, avoiding damage to precision components caused by mechanical clamping, while ensuring precise positioning during injection molding. A specially formulated electromagnetically shielded composite plastic is used during injection molding to encapsulate the circuit board and image sensor in a single step, with precise pre-reserved lens optical paths. This not only simplifies the traditional multi-step assembly process but also significantly enhances the sealing and integrity of the package, effectively preventing moisture and dust intrusion and meeting IP67 protection requirements.

[0035] The electromagnetic shielding composite plastic achieves excellent comprehensive performance through the synergistic design of multi-functional fillers. Conductive polymers, nano-carbon materials, two-dimensional transition metal carbonitrides, and graphene-coated carbonyl iron powder jointly construct a continuous conductive network, achieving a shielding effectiveness of no less than 45dB in the 2-18GHz frequency band. Combined with the Cu / Ni bilayer structure formed by subsequent gradient metallization, the overall electromagnetic shielding effectiveness is further enhanced. Simultaneously, the material possesses low volume resistivity, good thermal conductivity, and a low coefficient of thermal expansion, effectively dissipating working heat, suppressing static electricity accumulation, and maintaining dimensional stability in temperature-varying environments. This ensures the relative positional accuracy between the image sensor and the lens, thereby guaranteeing long-term reliable imaging quality.

[0036] This invention introduces several innovative measures in process control to improve product consistency and yield. During the injection molding stage, a pulsed holding pressure strategy is employed to effectively reduce internal stress and promote uniform filler orientation, minimizing the risk of warpage and cracking. After encapsulation, a combined ultraviolet-ozone surface activation process, along with a gradient metallization process combining chemical copper plating and magnetron sputtering nickel, ensures a strong bond between the metal shielding layer and the plastic substrate, achieving adhesion reaching the national standard level 0. The entire solution addresses electromagnetic protection, thermal management, mechanical strength, and precision assembly requirements, making it particularly suitable for the mass production of highly integrated smartphone camera modules, demonstrating significant technological advantages and industrialization value. Attached Figure Description

[0037] Figure 1 This is a flowchart of an injection molding packaging method for a mobile phone camera module according to an embodiment of this application. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions in the specific embodiments of the present invention will be clearly and completely described below.

[0039] This invention discloses an injection molding packaging method for a mobile phone camera module, which includes the following steps:

[0040] S1, Fixing and Preparation: Provide a camera module assembly including a circuit board, image sensor and lens, position it on the bearing surface, and apply a negative pressure of -0.05MPa to -0.08MPa through negative pressure air holes with an inner diameter of 0.8mm to 1.5mm that communicate with the bearing surface to adsorb and fix the camera module assembly.

[0041] S2, Integrated Injection Molding: Close the injection mold, inject electromagnetic shielding composite plastic into the cavity, perform encapsulation injection molding, and form an integrated package structure that completely encapsulates the circuit board and image sensor, while leaving room for the lens optical path;

[0042] S3, Post-processing and reinforcement: After injection molding, release the negative pressure and demold, deburr and clean the encapsulated structure, and perform fine machining on the mounting reference surface to ensure that the flatness error is no greater than 0.01mm.

[0043] The injection molding packaging method for mobile phone camera modules disclosed in this invention achieves packaging through a three-step process. First, a complete camera module assembly including a circuit board, image sensor, and lens is prepared. The assembly is placed on a dedicated support surface. The support surface has pre-set negative pressure vents that communicate with the internal air channels. The inner diameter of the vents is controlled between 0.8mm and 1.5mm. A negative pressure of -0.05MPa to -0.08MPa is applied to the vents through the air channels. The adsorption force generated by the air pressure difference firmly fixes the module assembly to the support surface, ensuring that the assembly does not shift its position during subsequent processing. Next, a customized injection mold is closed. The mold cavity matches the shape of the module assembly, with only a complete optical path channel reserved for the lens. Then, electromagnetic shielding composite plastic is injected into the cavity at a uniform speed. Through a coating injection molding process, the plastic completely encapsulates the circuit board and image sensor. After cooling, a complete integrated package structure is formed. After injection molding is completed, the negative pressure source is turned off to release the adsorption force, and then the demolding operation is carried out. After that, the edges and surfaces of the encapsulated structure are deburred to remove excess material debris generated during the injection molding process. Surface impurities are removed with special cleaning equipment. Finally, the mounting reference surface is precision machined using precision machining technology, and the flatness error is strictly controlled to not exceed 0.01mm.

[0044] Negative pressure adsorption fixation provides stable clamping force without damaging the precision structure of the module components, avoiding packaging deviations caused by component displacement during injection molding; integrated injection molding reduces the traditional multi-step assembly process, improves production efficiency, and at the same time gives the packaging structure better sealing performance, preventing moisture and dust intrusion; the precision machining of the mounting reference surface ensures the fit of the module in subsequent assembly, improving the overall assembly accuracy, while the design of reserving the lens optical path ensures that the camera imaging function is not affected by the packaging; the application of electromagnetic shielding composite plastic can also isolate the internal precision components from external electromagnetic interference, ensuring the stability of the module operation.

[0045] In one embodiment, the electromagnetic shielding composite plastic comprises: a matrix resin of glass fiber reinforced PA66 or polyphenylene sulfide, accounting for 55%-70% by mass; an electromagnetic shielding filler of 15%-30% by mass, comprising conductive polymers, nano-carbon materials, and two-dimensional transition metal carbonitrides, wherein the mass ratio of conductive polymers to nano-carbon materials is 5:1 to 1:1, and the two-dimensional transition metal carbonitrides account for 5%-15% of the total filler mass; reinforcing particles of 15%-25% by mass, wherein the reinforcing particles are a mixture of glass microspheres with a particle size of 5μm-20μm and short-cut carbon fibers with a length of 0.2mm-0.5mm in a mass ratio of 1:1 to 3:1; thermal conductivity regulating particles of 0.5%-8% by mass, which are particles of aluminum nitride and silicon dioxide compounded in a mass ratio of 2:1 to 4:1; and an antioxidant of 0.2%-0.5% by mass, which is a compounded antioxidant.

[0046] In the injection molding encapsulation method for mobile phone camera modules of this invention, the electromagnetic shielding composite plastic used for integrated injection molding is achieved by controlling the types, proportions, and preparation processes of each component. First, the type of matrix resin is determined. Based on the mechanical properties and temperature resistance requirements of the module encapsulation, glass fiber reinforced PA66 suitable for scenarios with high impact strength and weather resistance requirements, or polyphenylene sulfide suitable for high-temperature environments, is selected. The resin is weighed using an electronic balance at a mass ratio of 55%-70% to ensure the basic molding performance and structural stability of the material. Next, the electromagnetic shielding filler is prepared. Conductive polymers, nano-carbon materials, and two-dimensional transition metal carbonitrides are selected separately. The total mass ratio of the three is controlled to be 15%-30% using a mass measuring instrument. The conductive polymers and nano-carbon materials need to be weighed and mixed multiple times at a mass ratio of 5:1 to 1:1. The two-dimensional transition metal carbonitrides are weighed separately and ensured to account for 5%-15% of the total filler mass to ensure that the three components synergistically construct an effective conductive path. Subsequently, the reinforcing particles are processed and screened. Glass microspheres with a particle size ranging from 5μm to 20μm and short-cut carbon fibers with a length of 0.2mm to 0.5mm are weighed using a dense weighing device at a mass ratio of 1:1 to 3:1 and then placed in a low-speed mixer and stirred for 5-8 minutes to ensure initial homogeneity of the two types of particles. Next, thermal conductivity regulating particles are prepared by weighing high-purity aluminum nitride and silica particles at a mass ratio of 2:1 to 4:1 and pouring them into a dedicated mixing tank. Physical compounding is achieved through mechanical stirring. Finally, 0.2%-0.5% of a compounded antioxidant is weighed. All the above-mentioned matrix resin, electromagnetic shielding filler, reinforcing particles, thermal conductivity regulating particles, and antioxidant are then poured into a premixing device and stirred at a speed of 300-500 rpm for 10-15 minutes to complete the initial mixing of the components of the electromagnetic shielding composite plastic, laying the foundation for subsequent melt blending and granulation.

[0047] The high proportion of matrix resin ensures excellent injection molding flow, allowing for complete filling of the mold cavity. Meanwhile, the superior mechanical properties of glass fiber reinforced PA66 or polyphenylene sulfide enhance the impact and deformation resistance of the encapsulated structure. The multi-component combination and ratio of electromagnetic shielding fillers form a continuous conductive network within the material, effectively blocking external electromagnetic interference and protecting the circuit board and image sensor from signal interference, ensuring camera imaging quality. The specific size and ratio of glass microspheres and chopped carbon fibers in the reinforcing particles synergistically enhance the material's rigidity and impact resistance, reducing the risk of breakage during assembly or use. Thermally modulating particles optimize the material's heat conduction efficiency, promptly dissipating heat generated during module operation and preventing component damage due to overheating. A 0.2%-0.5% compound antioxidant delays material oxidation aging, extending the lifespan of the encapsulated structure and ensuring long-term stable operation of the camera module. Furthermore, the controlled proportions of each component balance the material's shielding, mechanical properties, thermal conductivity, and moldability, perfectly meeting the precision encapsulation requirements of mobile phone camera modules.

[0048] In the preparation of electromagnetic shielding composite plastics, to ensure uniform dispersion of various nanofillers during large-scale production and avoid degradation of shielding effectiveness and mechanical properties due to agglomeration, this invention adopts a diversified dispersion strategy. Pre-dispersion is achieved using a high-speed mixer to initially break up soft agglomerates of fillers in a dry state. During the melt blending stage of a twin-screw extruder, the high shear forces in the melting and homogenizing sections are utilized to achieve filler dispersion within the resin matrix. For easily agglomerated fillers such as Ti3C2T… X Its surface has been modified with silane coupling agent KH-550 to improve interfacial compatibility with the matrix resin and reduce the tendency to agglomerate. In each batch of production, samples can be taken from the granulated particles and the dispersion morphology of the filler in the matrix can be observed using a scanning electron microscope. If local agglomeration is found, the pre-dispersion time or the screw combination and speed of the twin-screw extruder can be adjusted in reverse to form a closed-loop quality control.

[0049] In one embodiment, the electromagnetic shielding filler also includes 3%-8% of multilayer graphene-coated carbonyl iron powder, wherein the number of graphene coating layers is 3-8, the particle size of the carbonyl iron powder is 1-10μm, and the graphene coating process is carried out under ultrasonic assistance with an ultrasonic power of 500-800W and a time of 1-3h.

[0050] In the preparation of the electromagnetic shielding composite plastic of this invention, to optimize the performance of the electromagnetic shielding filler, it is necessary to add carbonyl iron powder coated with multilayer graphene to the existing conductive polymer, nano-carbon materials, and two-dimensional transition metal carbonitrides. First, raw materials meeting the particle size requirements are screened, selecting high-purity carbonyl iron powder with a particle size range of 1-10 μm. Simultaneously, multilayer graphene with a controllable number of layers is prepared, and the number of coating layers is stabilized at 3-8 layers by controlling the graphene growth process. Then, the screened carbonyl iron powder and multilayer graphene are added to anhydrous ethanol dispersion medium in a preset ratio, poured into an ultrasonic reaction vessel, and the ultrasonic equipment is started with the power set to 500-800W, maintaining this power for 1-3 hours. During this process... The high-frequency vibrations generated by ultrasound break the agglomeration of graphene, promoting its uniform dispersion and tight coating on the surface of carbonyl iron powder, forming structurally stable graphene and carbonyl iron powder composite particles. After the coating process is completed, the composite particles are placed in a vacuum drying oven at a temperature of 60-80℃ for 2-3 hours to remove the dispersion medium. Then, they are weighed using a precision electronic balance to ensure that their mass accounts for 3%-8% of the total mass of the electromagnetic shielding filler. Finally, the composite particles are poured into a high-speed mixer along with the previously prepared conductive polymer, nano-carbon materials, and two-dimensional transition metal carbonitrides. The mixture is stirred at a speed of 800-1000 r / min for 10-15 minutes to ensure that the four components are fully mixed, forming a synergistic electromagnetic shielding filler.

[0051] The multi-layer graphene coating structure not only utilizes graphene's excellent conductivity to construct a continuous conductive path, but also encapsulates carbonyl iron powder through the sheet-like structure of graphene, preventing iron powder particle agglomeration and ensuring uniform dispersion of the filler in the matrix resin. The 1-10μm carbonyl iron powder particle size is compatible with the size of other fillers, preventing excessively large particles from affecting the material's injection molding flowability. At the same time, the magnetic shielding properties of the iron powder can form an electromagnetic synergistic shielding effect with the electrical shielding properties of conductive polymers and nano-carbon materials, enhancing the electromagnetic shielding effect. Ultrasonic assisted treatment with 500-800W power and a duration of 1-3 hours can control the coating uniformity, avoiding the incomplete coating problem caused by traditional mechanical stirring, ensuring that each carbonyl iron powder particle is effectively coated by graphene. The 3%-8% mass ratio design can leverage the shielding gain effect of graphene and carbonyl iron powder without increasing the material's brittleness due to an excessively high proportion, balancing shielding performance and mechanical properties. Ultimately, this allows the electromagnetic shielding composite plastic to more reliably isolate external electromagnetic interference, protecting the stable operation of the circuit board and image sensor inside the mobile phone camera module.

[0052] In one embodiment, the conductive polymer is at least one of polyaniline, polypyrrole, or poly(3,4-ethylenedioxythiophene), and the nanocarbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets, wherein the mass ratio of multi-walled carbon nanotubes to graphene nanosheets is 1:2 to 2:1, the aspect ratio of the multi-walled carbon nanotubes is 50-200, and the particle size of the graphene nanosheets is 5-20 μm.

[0053] In the preparation of the electromagnetic shielding filler for the electromagnetic shielding composite plastic of this invention, regarding the selection, specification control, and application of conductive polymers and nano-carbon materials, the conductive polymer is first selected and prepared. Based on the requirements of mobile phone camera module packaging for material conductivity, weather resistance, and processing compatibility, at least one of polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene) is selected as the conductive component. If corrosion resistance is a priority, polyaniline is preferred; if the mixing and dispersion of the material with the matrix resin needs to be optimized, polypyrrole can be selected; if higher conductivity is desired, poly(3,4-ethylenedioxythiophene) is preferred. After selection, the conductive polymer is processed into a powder with uniform particle size, controlled at 1-5 μm, using a grinding device to ensure compatibility with other fillers. It is then weighed according to a preset ratio and set aside for later use.

[0054] Multi-walled carbon nanotubes (MWCNTs) and graphene nanosheets were screened. The aspect ratio of the MHCNTs was measured using scanning electron microscopy to ensure it was within the range of 50-200. An aspect ratio that was too low would affect the construction of conductive pathways, while an aspect ratio that was too high would easily lead to agglomeration. Simultaneously, the particle size of the graphene nanosheets was measured using a laser particle size analyzer to ensure it was within the range of 5-20 μm. Particles that were too small would easily agglomerate, while particles that were too large would affect the material's injection molding flowability. After screening, MHCNTs and graphene nanosheets were weighed at a mass ratio of 1:2 to 2:1 using an electronic balance with a precision of 0.01%. Both were poured into a mixing container under inert gas protection and stirred at a low speed of 200-300 rpm for 15-20 minutes to achieve preliminary homogeneous mixing of the two nanomaterials. The prepared conductive polymer powder and the mixed nano-carbon material were poured into a high-speed mixer. At the same time, the previously prepared two-dimensional transition metal carbonitride and carbonyl iron powder coated with multilayer graphene were added. The mixture was stirred at 800-1000 r / min for 20-25 minutes, with the mixer stopped every 5 minutes to observe the mixing state, ensuring that the four shielding components were evenly dispersed and that there was no local agglomeration. Finally, a synergistic electromagnetic shielding filler was formed, laying the foundation for subsequent mixing with matrix resin, reinforcing particles, etc.

[0055] The multi-select design of conductive polymers can flexibly adapt to the performance requirements of different application scenarios, ensuring a balance between conductivity, processability, and weather resistance. The linear structure of multi-walled carbon nanotubes can build bridging conductive pathways within the material, while the sheet-like structure of graphene nanosheets can form a planar conductive network. When the two are mixed at a mass ratio of 1:2 to 2:1, synergistic conductivity between lines and surfaces can be achieved, improving the conductivity continuity of the electromagnetic shielding filler and thus enhancing the overall shielding effectiveness. Controlling the particle size of the conductive polymer, the aspect ratio of the multi-walled carbon nanotubes, and the particle size of the graphene nanosheets can avoid uneven dispersion caused by inconsistent filler specifications, ensuring that it can be fully integrated with the matrix resin and reinforcing particles without affecting the injection molding flowability of the material. This component, together with the previously added two-dimensional transition metal carbonitride and multilayer graphene-coated carbonyl iron powder, forms a multi-element synergistic shielding system, strengthening the ability to block electromagnetic interference in the 2-18GHz frequency band, providing more reliable electromagnetic protection for the circuit board and image sensor of the mobile phone camera module, and ensuring the stability of the camera imaging signal.

[0056] As one implementation method, the two-dimensional transition metal carbonitride is Ti3C2T. X Its surface is modified with silane coupling agent KH-550 at a temperature of 80-100℃ for 30-60 minutes to improve interfacial compatibility and dispersion stability with the matrix resin.

[0057] In the preparation of the electromagnetic shielding filler of the electromagnetic shielding composite plastic of the present invention, regarding the selection and modification of the two-dimensional transition metal carbonitride, the type of the two-dimensional transition metal carbonitride was first determined to be Ti3C2T. X First, regarding Ti3C2T X The powder was pretreated by placing it in a vacuum drying oven and drying it at 80-90℃ for 2-3 hours to remove adsorbed moisture from the powder surface and prevent moisture from affecting the reaction effect during subsequent modification. Then, a silane coupling agent KH-550 treatment solution was prepared. KH-550 was slowly added to anhydrous ethanol at a mass ratio of 10:1 to 20:1 while continuously stirring with a glass rod. A small amount of acetic acid was then added dropwise to adjust the pH of the treatment solution to 4-5 to promote the hydrolysis of KH-550 to generate silanol groups. Next, the pretreated Ti3C2T... X Add the powder to the KH-550 treatment solution, place the solution in a constant temperature water bath, maintain the water bath temperature at 80-100℃, and start the mechanical stirrer to continuously stir at a speed of 150-200 r / min to ensure the Ti3C2T X The powder is completely immersed in the treatment solution and in full contact. The reaction is maintained at this temperature for 30-60 minutes. During the reaction, the silanol groups generated by the hydrolysis of KH-550 react with Ti3C2T. X The hydroxyl groups on the surface undergo a condensation reaction in Ti3C2T X Organic functional groups were grafted onto the surface; after the reaction, the mixture was poured into centrifuge tubes and centrifuged at 3000-4000 r / min for 5-8 min to separate the modified Ti3C2T. X The solid particles were then washed repeatedly with anhydrous ethanol 3-4 times to remove unreacted KH-550 residue from the particle surface. Finally, they were placed in a vacuum drying oven and dried at 80-90℃ for 3-4 hours to obtain surface-modified Ti3C2T. X Powder; finally, the modified Ti3C2T X The powder is added to a high-speed mixer along with the previously prepared conductive polymer, nano-carbon material, and carbonyl iron powder coated with multilayer graphene, according to a preset ratio. The mixture is stirred at a speed of 800-1000 r / min for 20-25 min to achieve uniform mixing of the four shielding components and complete the preparation of the electromagnetic shielding filler.

[0058] Ti3C2T was selected. X As a two-dimensional transition metal carbonitride, it possesses excellent conductivity and a lamellar structure, enabling it to synergistically construct a dense conductive network with other shielding components, providing a foundation for electromagnetic shielding. Through modification treatment with the silane coupling agent KH-550 at 80-100℃ for 30-60 min, it can be used to create a dense conductive network in Ti3C2T. XSurface grafting of organic groups with better compatibility with the matrix resin enhances Ti3C2T X The modified Ti3C2T improves the interfacial bonding strength with the matrix resin, reduces the voids between them, and avoids problems such as cracking and detachment caused by poor interfacial bonding after material molding, while also improving the overall mechanical properties of the material; X The change in surface charge state can effectively suppress the aggregation of particles, ensuring that they are uniformly dispersed in the electromagnetic shielding filler and subsequent composite plastics, avoiding uneven shielding effectiveness due to local aggregation, and ensuring that all areas of the mobile phone camera module package can effectively block electromagnetic interference; as one implementation method, the electromagnetic shielding composite plastic has an electromagnetic interference shielding effectiveness of ≥45dB in the 2-18GHz frequency band, and a volume resistivity of ≤10Ω·cm, a thermal conductivity of ≥0.6W / (m·K), and a coefficient of thermal expansion of ≤25ppm / ℃.

[0059] For electromagnetic interference shielding effectiveness ≥45dB in the 2-18GHz band, the design relies on the multi-component synergistic design of the electromagnetic shielding filler. In the electromagnetic shielding filler, which accounts for 15%-30% of the total mass, conductive polymers and nano-carbon materials first construct the basic conductive pathways, the linear structure of multi-walled carbon nanotubes bridges the internal gaps of the material, and the sheet-like structure of graphene nanosheets forms a planar conductive layer; Ti3C2T modified with silane coupling agent KH-550... X Due to improved interfacial compatibility, it is uniformly dispersed and fills the gaps in the conductive network; the multilayer graphene-coated carbonyl iron powder, accounting for 3%-8% of the total filler mass, has electromagnetic dual shielding properties that work synergistically with the above components to form a dense electromagnetic barrier network inside the material, effectively absorbing and reflecting electromagnetic signals in the 2-18GHz frequency band, ultimately achieving a shielding efficiency of ≥45dB.

[0060] The volume resistivity ≤10Ω・cm is due to the continuity of the conductive path. The high proportion and reasonable combination of conductive components in the electromagnetic shielding filler ensure sufficient contact between conductive particles and avoid conductive breaks caused by particle agglomeration. On the other hand, the matrix resin has a certain compatibility, which allows the conductive filler to be evenly dispersed in it without local insulation areas, thereby reducing the overall resistance of the material and controlling the volume resistivity within the range of ≤10Ω・cm.

[0061] A thermal conductivity of ≥0.6 W / (m·K) is achieved through the synergistic effect of thermal conductivity regulating particles and reinforcing particles. Among the thermal conductivity regulating particles, which account for 0.5%-8% by mass, aluminum nitride has high thermal conductivity and can quickly transfer heat, while silicon dioxide assists in regulating the thermal conduction rate. At the same time, the short-cut carbon fibers with a length of 0.2 mm-0.5 mm in the reinforcing particles also have a certain thermal conductivity. Together with the thermal conductivity regulating particles, they form a thermal conduction channel inside the material. With the uniform dispersion of each component, a thermal conductivity of ≥0.6 W / (m·K) is finally achieved.

[0062] A coefficient of thermal expansion ≤25ppm / ℃ depends on the dimensional stability design of the matrix resin and reinforcing particles. The matrix resin is glass fiber reinforced PA66 or polyphenylene sulfide, which has a low coefficient of thermal expansion. Among the reinforcing particles, which account for 15%-25% by mass, the coefficients of thermal expansion of glass microspheres and short-cut carbon fibers are much lower than those of the resin. They can suppress the expansion trend of the resin when the temperature changes through physical constraint. At the same time, the silica in the thermal conductivity regulating particles also has low expansion characteristics, which helps to reduce the overall thermal expansion level of the material. Combined with the pulse holding pressure strategy during injection molding, the coefficient of thermal expansion is finally controlled at ≤25ppm / ℃.

[0063] With a shielding effectiveness of ≥45dB in the 2-18GHz band, it can completely block electromagnetic interference from other internal components of the phone, such as the motherboard, antenna, and external environment, avoiding circuit board signal disorder and image sensor image distortion, thus ensuring the quality of camera shooting. A volume resistivity of ≤10Ω・cm effectively releases static electricity generated during module operation, preventing electrostatic discharge from damaging precision components and extending the module's lifespan. A thermal conductivity of ≥0.6W / (m・K) quickly dissipates heat generated by the image sensor and circuit board during operation, preventing localized overheating that could lead to component performance degradation or damage, especially suitable for the heat dissipation needs of the confined space in a mobile phone. A coefficient of thermal expansion of ≤25ppm / ℃ ensures that the packaged structure will not crack or deform due to expansion and contraction during phone use, or cause the relative position of the lens and sensor to shift, ensuring the stability of the module structure and imaging accuracy, and overall improving the reliability and durability of the mobile phone camera module.

[0064] As one implementation, after step S3, a gradient metallization process is performed on the outer surface of the packaged structure to construct a composite electromagnetic shielding layer; the gradient metallization includes: first chemically plating copper with a thickness of 1-3 μm, and then vacuum magnetron sputtering nickel with a thickness of 1-5 μm to form a Cu / Ni double-layer structure, thereby improving the overall EMI shielding performance to ≥58dB; before metallization, the plastic substrate is subjected to ultraviolet-ozone combined treatment for 5-15 min.

[0065] After S3 precision machining, the packaged structure is placed in a dedicated integrated ultraviolet-ozone treatment device. Ensure that the device cavity is sealed and the surface of the packaged structure is unobstructed. The reserved lens optical path area must be covered in advance with a special high-temperature resistant and corrosion-resistant shielding film to prevent the treatment liquid or coating from affecting the lens optical path. After the device is started, it will release ultraviolet light of a specific wavelength and generate ozone. Maintain this treatment state for 5-15 minutes, during which the ozone concentration and ultraviolet intensity inside the device are monitored in real time to ensure the stability of the treatment process until the plastic substrate surface of the packaged structure is fully activated. Then, turn off the device, take out the packaged structure and remove the shielding film, and blow away any trace impurities that may remain on the surface with clean compressed air.

[0066] The activated encapsulated structure is transferred to a constant-temperature electroless copper plating bath. The plating bath contains a pre-prepared electroless copper plating solution composed of copper sulfate, formaldehyde, sodium hydroxide, and disodium EDTA. The temperature of the plating solution is controlled at 40-55℃, and the pH is adjusted to an alkaline range of 11-13 to ensure a stable reaction state. The encapsulated structure is completely immersed in the copper plating solution. Through a chemical reduction reaction, copper ions are uniformly deposited on its surface. During the process, the surface copper layer thickness is checked every 1-2 minutes using a plating thickness gauge. When the thickness reaches the preset value of 1-3 μm, the encapsulated structure is immediately removed from the copper plating bath and placed in a deionized water rinsing tank. It is rinsed repeatedly with flowing deionized water 3-4 times to thoroughly remove any residual copper plating solution. Then, it is placed in a hot air drying oven at 60-70℃ for 10-15 minutes to ensure no moisture remains on the surface.

[0067] After drying, fix the packaged structure onto the sample holder of the vacuum magnetron sputtering equipment. Double-check that the lens optical path area is unobstructed. If the masking film has fallen off during cleaning, it must be reapplied. Close the vacuum chamber and start the vacuum pump to reduce the pressure inside the vacuum chamber to 1×10⁻⁶. -3 -5×10 -3 A high vacuum of 0.1 Pa was established to eliminate air interference in the sputtering process. Then, high-purity argon gas (≥99.99%) was introduced into the vacuum chamber as the sputtering gas. The argon flow rate was adjusted to stabilize the pressure in the vacuum chamber at 0.1-0.5 Pa. A pure nickel target was set as the sputtering source, and the sputtering power was controlled at 100-200 W. Simultaneously, the sample holder was rotated at a constant speed of 5-10 r / min to ensure uniform sputtering on all surfaces of the packaged structure. The sputtering time was adjusted according to the target nickel layer thickness of 1-5 μm. After reaching the preset thickness, the sputtering source was turned off, and argon gas was continued to be introduced until the vacuum chamber pressure returned to normal. Then, the vacuum pump was turned off and the vacuum chamber was opened. The packaged structure was removed, and a Cu / Ni double-layer composite electromagnetic shielding layer was finally formed on its outer surface, improving the overall EMI shielding effectiveness to ≥58 dB.

[0068] Ultraviolet-ozone combined treatment effectively removes impurities such as oil and weak boundary layers from the surface of the plastic substrate of the encapsulation structure. Simultaneously, it generates polar functional groups such as hydroxyl and carboxyl groups on the surface, enhancing the adhesion between the subsequent metal plating layer and the plastic substrate. This prevents plating from peeling or blistering due to insufficient adhesion during long-term use, ensuring the long-lasting effectiveness of the shielding layer. Chemical copper plating possesses high conductivity, enabling the rapid construction of a continuous conductive shielding base layer on the surface of the encapsulation. Furthermore, the chemical plating process can penetrate complex areas such as corners and gaps of the encapsulation, achieving comprehensive coverage and preventing shielding gaps caused by areas without plating. Vacuum magnetron sputtering of nickel not only thickens the metal shielding layer and improves shielding effectiveness, but the nickel layer also possesses excellent corrosion resistance and... The wear resistance isolates the copper layer from external moisture, sweat, and other corrosive substances, extending the lifespan of the package. Meanwhile, the dense structure of the nickel layer fills any tiny pores in the copper layer, enhancing shielding integrity. Ultimately, the Cu / Ni dual-layer structure improves EMI shielding effectiveness to ≥58dB, compared to the ≥45dB shielding effectiveness of electromagnetic shielding composite plastics themselves. This enhances the ability to block electromagnetic interference in the 2-18GHz frequency band, providing more reliable protection for the internal circuit board and image sensor of the mobile phone camera module. It avoids imaging distortion and component failure caused by high-frequency electromagnetic signal interference, adapts to the complex electromagnetic environment generated by the dense components inside the mobile phone, and ensures long-term stable operation of the camera module.

[0069] To ensure uniform and stable UV-ozone combined treatment, and thus guarantee excellent and reliable adhesion between the Cu / Ni gradient metal shielding layer and the plastic substrate, the integrated UV-ozone treatment equipment is equipped with a closed-loop feedback control system. The system monitors the ozone concentration, temperature, and humidity within the chamber in real time, and automatically adjusts the ozone generator power, heating module, and humidification / dehumidification devices via a microprocessor to ensure optimal treatment parameters and an ozone concentration of 50-100 mg / m³. 3 The temperature should be 40-60℃, and the relative humidity 30%-50%. During the entire treatment period, 5-15 minutes, the fluctuation range should not exceed ±5% of the set value. Before formally commencing gradient metallization mass production, it is recommended to use test pieces made from the same batch of materials as the packaged structure. After undergoing the same UV-ozone combined treatment, perform small-area electroless copper plating and nickel sputtering. Immediately afterwards, conduct a cross-cut adhesion test according to GB / T9286-1998 standard. Only after confirming a grade of 0 should subsequent processing be carried out on the formal products. This step can serve as a first-piece inspection system in the production process, effectively preventing batch adhesion problems. After the UV-ozone combined treatment, perform palladium-based sensitization-activation treatment on the surface of the packaged structure or use a palladium-free direct electroless copper plating process to form catalytic active centers on the non-metallic substrate, ensuring the continuity and adhesion of the subsequent electroless copper plating layer.

[0070] As one implementation method, the specific conditions for the combined ultraviolet-ozone treatment are as follows: using dual-band ultraviolet light with wavelengths of 185nm and 254nm, and in an environment with an ozone concentration of 50-100mg / m3, a treatment temperature of 40-60℃, and a relative humidity of 30%-50%, the substrate of the encapsulated structure is surface activated for 5-15 minutes to improve the adhesion between the Cu / Ni gradient metal shielding layer and the plastic substrate, ensuring that its bonding strength reaches level 0 as specified in GB / T9286-1998 standard.

[0071] An integrated ultraviolet-ozone system with dual-band ultraviolet generation, an ozone concentration control module, and a closed-loop temperature and humidity control system was selected. The system is pre-installed with dedicated ultraviolet lamps with wavelengths of 185nm and 254nm, and is also equipped with high-precision ozone concentration, temperature, and humidity sensors. During commissioning, the system was first started under no-load operation, and the power output of the 185nm and 254nm ultraviolet lamps was adjusted to stabilize the lamp emission. Then, the ozone concentration inside the chamber was gradually increased to 50-100 mg / m³ using the ozone generator adjustment knob. 3 In the specified range, simultaneously turn on the heating module to control the cavity temperature at 40-60℃, and start the humidification or dehumidification device to stabilize the relative humidity at 30%-50%. Continuously monitor for 3-5 minutes to ensure that there are no fluctuations in the parameters, and then turn off the equipment for subsequent use.

[0072] After the encapsulation structure is processed in step S3, it is fixed on the sample holder of the equipment using a special high-temperature resistant clamp to ensure that the surface of the encapsulation structure can be directly exposed to ultraviolet radiation and ozone. Then, a high-temperature resistant and ozone-resistant polytetrafluoroethylene shielding film is used to cover the lens optical path area of ​​the encapsulation structure, and the edges are sealed with high-temperature resistant tape to prevent ultraviolet radiation and ozone from damaging the optical path area or to prevent subsequent metal coating from contaminating the optical path.

[0073] The fixed encapsulated structure is inserted into the equipment cavity. After closing the cavity door, the equipment is restarted, simultaneously activating the 185nm and 254nm dual-band ultraviolet lamps, ozone generator, and temperature and humidity control system. During the process, the equipment displays and records ozone concentration, temperature, and humidity data in real time. Operators check the parameter status every two minutes through the equipment's observation window and data panel. If the ozone concentration is below 50 mg / m³... 3 Then appropriately increase the ozone generator power, above 100mg / m³. 3Reduce power; increase heating module output when temperature is below 40℃, and pause heating when temperature is above 60℃; activate humidification device when humidity is below 30%RH, and activate dehumidification device when humidity is above 50%RH to ensure parameters remain stable within the set range throughout the entire process. After continuous treatment for 5-15 minutes, first turn off the ultraviolet lamp and ozone generator, keep the temperature and humidity system running for 1 minute, then open the cavity door to remove the encapsulated structure, remove the shielding film in the lens optical path area, and use clean inert gas to blow away any trace amounts of ozone and impurities that may remain on the surface of the encapsulated structure to complete the surface activation treatment.

[0074] Finally, the activation effect was verified: the surface of the activated encapsulated structure was tested using a cross-cut adhesion tester in accordance with the GB / T9286-1998 standard. A 1mm×1mm grid array was drawn on the surface with a cross-cut knife, a special test tape was applied and peeled off at a uniform speed, and it was observed that no coating peeled off on the inner surface of the grid. This confirmed that the surface adhesion reached level 0 as specified in the standard, ensuring the reliability of the subsequent metal plating process.

[0075] The dual-band ultraviolet light works synergistically. 185nm ultraviolet light efficiently decomposes oxygen in the air to generate ozone, while 254nm ultraviolet light enhances the oxidizing activity of ozone. Together, they thoroughly remove oil, dust, and weak plastic boundary layers from the surface of the encapsulated structure. Simultaneously, they generate polar functional groups such as hydroxyl and carboxyl groups on the surface, providing a good adhesion base for subsequent electroless copper plating and preventing voids between the plating layer and the substrate; 0-100mg / m 3 The specified ozone concentration range ensures effective oxidation and cleaning while preventing excessive ozone concentration from causing aging and embrittlement of the plastic substrate, thus extending the lifespan of the encapsulated structure. Temperature control at 40-60℃ and relative humidity at 30%-50% accelerates the chemical reaction between ozone and the plastic surface, improving activation efficiency. This avoids slow reactions due to excessively low temperatures, damage to the substrate structure due to excessively high temperatures, condensation due to excessively high humidity, and insufficient reaction sufficiency due to excessively low humidity. Adhesion reaches GB / T9286-1998 standard level 0, meaning that the subsequent deposition of a 1-3μm electroless copper plating layer and a 1-5μm… The vacuum magnetron sputtered nickel layer adheres tightly to the plastic substrate surface, preventing plating peeling and blistering during long-term use. This ensures the integrity of the Cu / Ni dual-layer composite shielding layer, maintaining an overall EMI shielding effectiveness of ≥58dB. It effectively blocks complex electromagnetic interference within the mobile phone, protecting the circuit board and image sensor for stable operation. The entire process eliminates the need for chemical cleaning agents, avoiding contamination of the encapsulation structure or subsequent metal plating by cleaning agent residues, thus meeting green production requirements. Furthermore, the adjustable processing parameters ensure consistent activation effects for each encapsulation structure during mass production, improving product yield.

[0076] As one implementation method, the injection molding process parameters in step S2 are: barrel temperature 235℃-265℃, nozzle temperature 245℃-275℃, mold temperature 90℃-125℃, injection pressure 85-125MPa, holding pressure 55-85MPa, holding time 6-18s, and cooling time 25-45s. Furthermore, a pulsed holding pressure strategy is adopted during injection molding to reduce internal stress and improve the uniformity of filler orientation. The pulsed holding pressure strategy involves periodic fluctuations in the holding pressure within a set range. This pressure fluctuation can create micro-disturbances in the melt, breaking the directional arrangement of the filler formed by shear flow, making its distribution more random and uniform in three-dimensional space, thereby reducing product anisotropy and internal stress caused by uneven orientation.

[0077] A horizontal injection molding machine suitable for electromagnetically shielded composite plastics is selected. This equipment must have a segmented temperature control system, a closed-loop pressure control system, and a pulse pressure holding function. After starting the equipment, the barrel temperature is first set: through the embedded temperature sensor on the barrel and the segmented temperature control module, the overall barrel temperature is adjusted to 235℃-265℃. The barrel can be subdivided into a feeding section, a melting section, and a homogenizing section according to the melting characteristics of the plastic. The temperature of each section is independently adjusted by the temperature controller. For example, the temperature of the feeding section is slightly lower to prevent the raw material from melting and clumping prematurely. The melting section and the homogenizing section are maintained at 250℃-265℃ to ensure that the plastic melts fully. Then, the nozzle temperature is adjusted. The temperature is set to 245℃-275℃ through an independent thermocouple sensor at the nozzle. The temperature data is monitored and fed back in real time. If the nozzle temperature is lower than 245℃, the heating power is increased to prevent the plastic from cooling and solidifying and clogging the nozzle. If it is higher than 275℃, the power is reduced to prevent the plastic from overheating and degrading.

[0078] Multiple heating elements and cooling water channels are pre-installed inside the injection mold, connected to a mold temperature controller set to 90℃-125℃. The mold temperature controller circulates heat transfer oil to the mold's water channels, and works with temperature sensors on the mold surface to monitor the temperature in real time. If the local temperature of the mold is below 90℃, the mold temperature controller increases the temperature of the heat transfer oil and accelerates the circulation rate; if it is above 125℃, it decreases the temperature of the heat transfer oil to ensure uniform temperature on the mold cavity surface and avoid uneven shrinkage of the molded part due to temperature differences.

[0079] The injection molding machine's pressure control system sets the injection pressure to 85MPa-125MPa. A lower pressure is used during the initial filling stage to prevent high-speed impact of molten plastic on the mold cavity, which could lead to overflow or displacement. During the later stages of filling, the pressure is gradually increased to 100MPa-125MPa to ensure complete filling of the cavity, covering the circuit board and image sensor, and reserving space for the lens's optical path. During the holding pressure stage, the pressure is set to 55MPa-85MPa, and the holding time is set to 6s-18s. Simultaneously, a pulse-type holding pressure strategy is enabled in the injection molding machine's control system: the pulse period is set to 2s-3s, and the pressure fluctuates intermittently within the 55MPa-85MPa range. For example, it is first held at 55MPa for 2s, then increased to 70MPa and held for 2s, and finally reduced to 60MPa until the holding time ends. Throughout the process, the pressure value is calibrated in real-time using a pressure sensor to ensure it meets the parameter requirements.

[0080] The mold cooling water circuit is connected to a chiller. The water flow rate of the cooling water circuit is adjusted according to the thickness of the encapsulated structure to stabilize the cooling time between 25s and 45s. During the cooling process, the plastic curing progress is monitored by a temperature sensor in the mold cavity. When the surface temperature of the plastic drops below the glass transition temperature of the base resin and is maintained at that temperature for 3s-5s, the cooling time is confirmed to be up to standard, and demolding is prepared.

[0081] The control of barrel, nozzle, and mold temperatures is adapted to the melting characteristics of electromagnetic shielding composite plastics, avoiding overheating degradation or incomplete melting of the matrix resin, ensuring the fluidity and mechanical properties of the plastic, and ensuring that the electromagnetic shielding filler is not damaged by high temperatures, maintaining its shielding effectiveness. The combination of injection pressure of 85MPa-125℃ and holding pressure of 55MPa-85MPa not only fills the mold cavity to achieve complete encapsulation, but also compensates for the volume shrinkage of the plastic during cooling through holding pressure, avoiding shrinkage cavities and depressions in the molded parts. The pulsed holding pressure strategy can reduce internal stress concentration in the plastic, reducing the risk of cracking and warping after demolding of the encapsulated structure, while promoting uniform orientation of the shielding filler and reinforcing particles, avoiding uneven performance caused by local agglomeration. The cooling time of 25s-45s ensures that the plastic is fully shaped and the structure is stable after demolding, providing a good foundation for deburring and finishing in S3, and reducing errors in subsequent processes. The synergistic effect of the overall process parameters ultimately achieves high-quality molding of the integrated encapsulation structure, ensuring its compatibility with the precision encapsulation and stable operation requirements of mobile phone camera modules.

[0082] As one implementation method, the preparation method of electromagnetic shielding composite plastic includes: S2.1 Vacuum drying of all solid raw materials at 80℃-100℃ for 4-6 hours, controlling the moisture content to ≤0.05%; S2.2 Pre-dispersing the electromagnetic shielding filler in a high-speed mixer at a speed of 800-1200 r / min for 10-20 minutes; S2.3 Adding the matrix resin, reinforcing particles, thermal conductivity regulating particles, and antioxidant, and continuing mixing for 20-40 minutes; S2.4 Feeding the mixture into a twin-screw extruder for melt blending and granulation, wherein the process parameters of the twin-screw extruder are: feeding section 180℃-200℃, melting section 230℃-250℃, homogenization section 240℃-260℃, die head temperature 235℃-255℃, and screw speed 300-500 r / min.

[0083] Collect all solid raw materials, including matrix resin, electromagnetic shielding filler, reinforcing particles, thermal conductivity regulating particles, and compound antioxidants. Place these materials separately into perforated drying trays, spreading them evenly to a thickness of 2-3 cm to ensure uniform heating, and then place them in a vacuum drying oven. Close the oven door, start the vacuum pump to evacuate to an absolute pressure ≤1 kPa, and then turn on the heating module to raise the temperature to 80℃-100℃, maintaining this temperature and vacuum state for 4-6 hours. During the drying process, check the condition of the raw materials every hour through the observation window of the drying oven to prevent localized overheating and clumping. After drying, wait for the temperature to drop to room temperature before removing the raw materials and immediately use a Karl Fischer moisture analyzer to randomly sample and test the moisture content, ensuring that the moisture content of all raw materials is ≤0.05%. If the moisture content is not met, return them to the drying oven and dry for another 1-2 hours using the same parameters.

[0084] Pour all the dried electromagnetic shielding filler into the sealed chamber of the high-speed mixer. Close the chamber door, start the mixer, and set the speed to 800-1200 r / min. Maintain this speed for 10-20 minutes. During the mixing process, observe the dispersion of the filler in real time through the transparent observation window of the mixer. If local agglomeration is found, increase the speed by 50-100 r / min. After mixing for 10 minutes, stop the machine, open the chamber door, and take 3-5 samples from different locations using a sampling spoon. Observe the particle dispersion uniformity using an optical microscope. If there is still obvious agglomeration, extend the mixing time by 5-10 minutes until there is no obvious agglomeration of filler in all samples, ensuring that the pre-dispersion effect meets the standard.

[0085] Add the dried matrix resin, reinforcing particles, thermal conductivity regulating particles, and compounded antioxidant to the pre-dispersed electromagnetic shielding filler in a predetermined mass ratio. First, add the matrix resin and start a high-speed mixer at 800 rpm for 5-8 minutes to allow the matrix resin and pre-dispersed filler to initially fuse. Then add the reinforcing particles and increase the speed to 1000 rpm, continuing mixing for 8-12 minutes to ensure the reinforcing particles are uniformly embedded in the resin and filler mixture. Finally, add the thermal conductivity regulating particles and compounded antioxidant, maintaining a speed of 1000-1200 rpm for 7-10 minutes, with a total mixing time of 20-40 minutes. After mixing, take samples to test the component homogeneity of the mixture. Analyze the elemental content at different sampling points using X-ray fluorescence spectrometry, ensuring that the deviation of each element content is ≤5% to be considered a successful mixture.

[0086] The properly mixed material is fed into the feed hopper of the twin-screw extruder, and fed into the extruder at a uniform rate of 10-15 kg / h by the feeder. The twin-screw extruder is started, and the temperatures of each section are adjusted according to preset parameters: the feeding section temperature is set to 180℃-200℃, the melting section temperature to 230℃-250℃, the homogenization section temperature to 240℃-260℃, and the die head temperature to 235℃-255℃. Simultaneously, the screw speed is set to 300-500 r / min. The operating status is monitored in real time through the extruder's torque monitoring system. If the torque exceeds the rated value by 10%, the feeding rate is appropriately reduced or the melting section temperature is increased to ensure stable equipment operation. After the molten material is extruded from the die head, it immediately enters a water cooling tank to cool to room temperature. Then, it is cut into uniform particles of 2-3 mm in length by a pelletizer. Finally, the particles are sent to a vibrating screen to remove excessively fine or long particles, obtaining the final electromagnetic shielding composite plastic particles.

[0087] S2.1 vacuum drying thoroughly removes moisture from the raw materials, preventing moisture from vaporizing and generating bubbles during subsequent injection molding, ensuring the sealing of the encapsulated structure, and preventing moisture from causing hydrolytic degradation of the matrix resin, thus maintaining the material's mechanical properties and shielding effectiveness. S2.2 pre-dispersion breaks up the initial agglomeration of the electromagnetic shielding filler, laying a uniform foundation for subsequent multi-component mixing, ensuring the filler forms a continuous conductive network in the final material, guaranteeing an electromagnetic interference shielding effectiveness ≥45dB and a volume resistivity ≤10Ω・cm. S2.3 staged mixing avoids stratification of raw materials with different densities and particle sizes, ensuring uniform reinforcing particles. The distribution enhances the material's impact resistance, and the thermal conductivity regulating particles are evenly dispersed to achieve a thermal conductivity ≥0.6W / (m・K). The antioxidant is evenly covered to delay material aging. The strong shear and temperature control of the twin-screw extrusion in S2.4 enable the full dispersion of each component in the molten state, avoiding performance fluctuations caused by uneven local composition. At the same time, it adapts to the melting characteristics of the matrix resin, preventing resin overheating and degradation. The prepared particles have consistent flowability, providing stable raw materials for injection molding in step S2. Ultimately, it ensures that the coefficient of thermal expansion of the encapsulated structure is ≤25ppm / ℃, meeting the requirements of precision encapsulation and long-term stable use of mobile phone camera modules.

[0088] All examples and comparative examples were tested using a unified performance testing standard. Electromagnetic interference (EMI) shielding effectiveness was tested according to GB / T25471-2010 standard within the 2-18 GHz frequency band; volume resistivity was measured according to GB / T1410-2006 standard using the four-probe method; thermal conductivity was tested according to GB / T22588-2008 standard using the laser scintillation method; coefficient of thermal expansion was tested according to GB / T1036-2008 standard within a temperature range of -40 to 85℃; coating adhesion was tested according to GB / T9286-1998 standard using the cross-cut adhesion test, where level 0 is the best and level 5 is the worst; and sealing performance was tested according to IP67 standard, by immersing the sample in 1 m of water for 30 minutes to check for water ingress.

[0089] Example

[0090] Example 1

[0091] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%, and the specific formula is as follows: the matrix resin is glass fiber reinforced PA66, accounting for 65% by mass; the electromagnetic shielding filler accounts for 22% by mass; the reinforcing particles account for 12% by mass; the thermal conductivity regulating particles account for 0.7% by mass; and the antioxidant is a compound antioxidant, accounting for 0.3% by mass.

[0092] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is polyaniline, with a mass ratio of 3:1 to the nano-carbon material; the nano-carbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 100 and the graphene nanosheets having a particle size of 10μm, and a mass ratio of 1:1; Ti3C2T X The modified carbonyl iron powder, treated with silane coupling agent KH-550 at a temperature of 90℃ for 45 minutes, accounts for 10% of the total mass of the electromagnetic shielding filler. The carbonyl iron powder with multilayer graphene coating has 3 layers of graphene coating and a particle size of 5μm. The graphene coating process is carried out under ultrasonic assistance with an ultrasonic power of 600W for 2 hours. This composite particle accounts for 5% of the total mass of the electromagnetic shielding filler.

[0093] The reinforcing particles consist of glass microspheres with a diameter of 10 μm and short-cut carbon fibers with a length of 0.3 mm, with a mass ratio of 2:1; the thermal conductivity regulating particles are a mixture of aluminum nitride and silicon dioxide, with a mass ratio of 3:1.

[0094] In the preparation process of the electromagnetic shielding composite plastic, the raw materials were first dried. All solid raw materials were vacuum dried at 90℃ for 5 hours, controlling the moisture content to 0.04%. Then, the electromagnetic shielding filler was pre-dispersed in a high-speed mixer at a speed of 1000 r / min for 15 minutes. After pre-dispersion, the matrix resin, reinforcing particles, thermal conductivity regulating particles, and antioxidant were added, and mixing continued for 30 minutes. The mixture was then fed into a twin-screw extruder for melt blending and granulation. The twin-screw extruder had a feeding section temperature of 190℃, a melting section temperature of 240℃, a homogenization section temperature of 250℃, a die head temperature of 245℃, and a screw speed of 400 r / min. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18 GHz frequency band was 47 dB, meeting the design requirement of ≥45 dB.

[0095] In the injection molding process of the mobile phone camera module, the injection molding process parameters in step S2 are set as follows: barrel temperature 250℃, nozzle temperature 260℃, mold temperature 105℃, injection pressure 100MPa, holding pressure 70MPa, using a pulse holding pressure strategy. Pulse holding pressure means that the holding pressure fluctuates within ±10-15MPa of the set value, with a cycle of 2-3 seconds, a pulse period of 2.5s, a holding time of 12s, and a cooling time of 35s. Before gradient metallization after step S3, the substrate of the encapsulation structure is first subjected to ultraviolet-ozone combined treatment, using dual-band ultraviolet light with wavelengths of 185nm and 254nm, and an ozone concentration of 75mg / m³. 3The process is carried out at 50℃ and 40% relative humidity for 10 minutes. During the gradient metallization process, copper is first electrolessly plated to a thickness of 2μm, followed by vacuum magnetron sputtering of nickel to a thickness of 3μm.

[0096] Tests showed that the EMI shielding effectiveness of the encapsulation structure with gradient metallization layer prepared in this embodiment is 62dB, the volume resistivity is 5Ω・cm, the thermal conductivity is 0.8W / (m・K), the coefficient of thermal expansion is 22ppm / ℃, the coating adhesion reaches level 0, and the sealing performance meets the IP67 standard requirements.

[0097] Example 2

[0098] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%. The specific formula is as follows: the matrix resin is polyphenylene sulfide, accounting for 70% by mass; the electromagnetic shielding filler accounts for 15% by mass; the reinforcing particles account for 14.8% by mass; and the antioxidant is a compound antioxidant, accounting for 0.2% by mass.

[0099] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is polypyrrole, with a mass ratio of 5:1 to the nano-carbon material; the nano-carbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 200 and the graphene nanosheets having a particle size of 20μm, and a mass ratio of 2:1; Ti3C2T X The modified carbonyl iron powder, treated with silane coupling agent KH-550 at 80℃ for 30 min, accounts for 5% of the total mass of the electromagnetic shielding filler. The carbonyl iron powder with multi-layer graphene coating has 4 graphene coating layers and a carbonyl iron powder particle size of 1 μm. The graphene coating process is carried out under ultrasonic assistance with an ultrasonic power of 500 W for 1 h. This composite particle accounts for 3% of the total mass of the electromagnetic shielding filler.

[0100] The reinforcing particles consist of glass microspheres with a diameter of 5 μm and short-cut carbon fibers with a length of 0.2 mm, with a mass ratio of 1:1.

[0101] In the raw material drying process, all solid raw materials were vacuum dried at 80℃ for 4 hours, controlling the moisture content to 0.05%. The electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 800 r / min for 10 minutes, after which other components were added and mixing continued for 20 minutes. The mixture was then fed into a twin-screw extruder for melt blending and granulation. The twin-screw extruder had a feed section temperature of 180℃, a melt section temperature of 230℃, a homogenization section temperature of 240℃, a die head temperature of 235℃, and a screw speed of 300 r / min. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18 GHz frequency band was 45 dB, meeting the design requirement of ≥45 dB.

[0102] In step S2 of injection molding, the barrel temperature is 235℃, the nozzle temperature is 245℃, the mold temperature is 90℃, the injection pressure is 85MPa, the holding pressure is 55MPa, the pulse holding cycle is 2s, the holding time is 6s, and the cooling time is 25s. The UV-ozone combined treatment before gradient metallization uses dual-band UV light with wavelengths of 185nm and 254nm, at an ozone concentration of 50mg / m³. 3 The process involves treating the sample at 40℃ and 30% relative humidity for 5 minutes. Gradient metallization is performed by first electroless copper plating to a thickness of 1 μm, followed by vacuum magnetron sputtering of nickel to a thickness of 1 μm.

[0103] Test results show that the EMI shielding effectiveness of the package structure with gradient metallization layer in this embodiment is 58dB, the volume resistivity is 8Ω・cm, the thermal conductivity is 0.6W / (m・K), the coefficient of thermal expansion is 25ppm / ℃, the coating adhesion is grade 0, and the sealing performance meets the IP67 standard.

[0104] Example 3

[0105] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%. The specific formula is as follows: the matrix resin is glass fiber reinforced PA66, accounting for 55% by mass; the electromagnetic shielding filler accounts for 30% by mass; the reinforcing particles account for 14.5% by mass; and the antioxidant is a compound antioxidant, accounting for 0.5% by mass.

[0106] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is poly(3,4-ethylenedioxythiophene), with a mass ratio of 1:1 to the nano-carbon material; the nano-carbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 50 and the graphene nanosheets having a particle size of 5μm, and a mass ratio of 1:2; Ti3C2T X Modified with silane coupling agent KH-550, the treatment temperature was 100℃ and the treatment time was 60min, accounting for 15% of the total mass of the electromagnetic shielding filler; in the multi-layer graphene-coated carbonyl iron powder, the number of graphene coating layers was 6, the carbonyl iron powder particle size was 10μm, the ultrasonic-assisted coating power was 800W and the time was 3h, and the composite particles accounted for 8% of the total mass of the electromagnetic shielding filler.

[0107] The reinforcing particles consist of glass microspheres with a diameter of 20 μm and short-cut carbon fibers with a length of 0.5 mm, with a mass ratio of 3:1.

[0108] The raw materials were vacuum dried at 100℃ for 6 hours, with the moisture content controlled at 0.03%. The electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 1200 rpm for 20 minutes, followed by the addition of other components and continued mixing for 40 minutes. The twin-screw extruder was used with the following temperatures: feeding section temperature 200℃, melting section temperature 250℃, homogenization section temperature 260℃, die head temperature 255℃, and screw speed 500 rpm, to complete melt blending and granulation. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18GHz frequency band was 52dB, meeting the design requirement of ≥45dB.

[0109] The parameters for injection molding step S2 are: barrel temperature 265℃, nozzle temperature 275℃, mold temperature 125℃, injection pressure 125MPa, holding pressure 85MPa, pulse holding cycle 3s, holding time 18s, and cooling time 45s. The combined ultraviolet-ozone treatment uses dual-band 185nm and 254nm ultraviolet light at an ozone concentration of 100mg / m³. 3 The process involves treating the material at 60℃ and 50% relative humidity for 15 minutes. Gradient metallization is performed by first electroless copper plating to a thickness of 3 μm, followed by vacuum magnetron sputtering of nickel to a thickness of 5 μm.

[0110] Testing revealed that the EMI shielding effectiveness of the encapsulation structure with gradient metallization layer in this embodiment is 65dB, the volume resistivity is 3Ω・cm, the thermal conductivity is 1.0W / (m・K), the coefficient of thermal expansion is 20ppm / ℃, the coating adhesion reaches level 0, and the sealing performance meets the IP67 standard.

[0111] Example 4

[0112] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%. The specific formula is as follows: the matrix resin is polyphenylene sulfide, accounting for 60% by mass; the electromagnetic shielding filler accounts for 25% by mass; the reinforcing particles account for 14.6% by mass; and the antioxidant is a compound antioxidant, accounting for 0.4% by mass.

[0113] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is a mixture of polyaniline and polypyrrole in a 1:1 mass ratio, and the mass ratio of this conductive polymer mixture to the nano-carbon material is 4:1; the nano-carbon material consists of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 150 and the graphene nanosheets having a particle size of 15μm, in a 1:1 mass ratio; Ti3C2T X Modified with silane coupling agent KH-550, treated at 95℃ for 50 min, accounting for 12% of the total mass of electromagnetic shielding filler; In the multi-layer graphene-coated carbonyl iron powder, the number of graphene coating layers is 5, the carbonyl iron powder particle size is 8μm, the ultrasonic-assisted coating power is 700W, and the time is 2.5h, the composite particles account for 6% of the total mass of electromagnetic shielding filler.

[0114] The reinforcing particles consist of glass microspheres with a diameter of 15 μm and short-cut carbon fibers with a length of 0.4 mm, with a mass ratio of 2:1.

[0115] The raw materials were vacuum dried at 95℃ for 4.5 hours, with a moisture content of 0.04%. The electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 1100 r / min for 18 minutes, followed by the addition of other components and continued mixing for 35 minutes. The twin-screw extruder was used to complete melt blending and granulation at a feeding section temperature of 195℃, a melting section temperature of 245℃, a homogenization section temperature of 255℃, a die head temperature of 250℃, and a screw speed of 450 r / min. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18 GHz frequency band was 49 dB, meeting the design requirement of ≥45 dB.

[0116] The parameters for injection molding step S2 are set as follows: barrel temperature 255℃, nozzle temperature 265℃, mold temperature 115℃, injection pressure 110MPa, holding pressure 75MPa, pulse holding cycle 2.8s, holding time 15s, and cooling time 40s. The combined ultraviolet-ozone treatment uses dual-band 185nm and 254nm ultraviolet light at an ozone concentration of 80mg / m³. 3 The process was carried out at 55℃ and 45% relative humidity for 12 minutes. Gradient metallization was performed by first electroless copper plating to a thickness of 2.5 μm, followed by vacuum magnetron sputtering of nickel to a thickness of 4 μm.

[0117] Test results show that the EMI shielding effectiveness of the encapsulation structure with gradient metallization layer in this embodiment is 63dB, the volume resistivity is 4Ω・cm, the thermal conductivity is 0.9W / (m・K), the coefficient of thermal expansion is 21ppm / ℃, the coating adhesion is grade 0, and the sealing performance meets the IP67 standard.

[0118] Example 5

[0119] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%. The specific formula is as follows: the matrix resin is glass fiber reinforced PA66, accounting for 62% by mass; the electromagnetic shielding filler accounts for 18% by mass; the reinforcing particles account for 19.65% by mass; and the antioxidant is a compound antioxidant, accounting for 0.35% by mass.

[0120] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is a mixture of poly(3,4-ethylenedioxythiophene) and polyaniline in a mass ratio of 2:1, and the mass ratio of this mixture to the nano-carbon material is 2:1; the nano-carbon material consists of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 120 and the graphene nanosheets having a particle size of 12μm, in a mass ratio of 2:1; Ti3C2T XModified with silane coupling agent KH-550, treated at 85℃ for 40 min, accounting for 8% of the total mass of electromagnetic shielding filler; In the multi-layer graphene-coated carbonyl iron powder, the number of graphene coating layers is 7, the carbonyl iron powder particle size is 6μm, the ultrasonic-assisted coating power is 650W, and the time is 2.2h, the composite particles account for 4% of the total mass of electromagnetic shielding filler.

[0121] The reinforcing particles consist of glass microspheres with a diameter of 12 μm and short-cut carbon fibers with a length of 0.35 mm, with a mass ratio of 2.5:1.

[0122] The raw materials were vacuum dried at 92℃ for 5 hours, with the moisture content controlled at 0.035%. The electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 1050 r / min for 16 minutes, followed by the addition of other components and continued mixing for 32 minutes. The twin-screw extruder was used with a feeding section temperature of 192℃, a melting section temperature of 242℃, a homogenization section temperature of 252℃, a die head temperature of 248℃, and a screw speed of 420 r / min to complete melt blending and granulation. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18 GHz frequency band was 46 dB, meeting the design requirement of ≥45 dB.

[0123] The parameters for injection molding step S2 are: barrel temperature 252℃, nozzle temperature 262℃, mold temperature 110℃, injection pressure 105MPa, holding pressure 72MPa, pulse holding cycle 2.6s, holding time 14s, and cooling time 38s. The combined ultraviolet-ozone treatment uses dual-band 185nm and 254nm ultraviolet light at an ozone concentration of 70mg / m³. 3 The process was carried out at 48℃ and 38% relative humidity for 11 minutes. Gradient metallization was performed by first electroless copper plating to a thickness of 2.2 μm, followed by vacuum magnetron sputtering of nickel to a thickness of 3.5 μm.

[0124] Testing revealed that the EMI shielding effectiveness of the encapsulation structure with gradient metallization layer in this embodiment is 61dB, the volume resistivity is 4.5Ω・cm, the thermal conductivity is 0.85W / (m・K), the coefficient of thermal expansion is 21.5ppm / ℃, the coating adhesion reaches level 0, and the sealing performance meets the IP67 standard.

[0125] Example 6

[0126] In this embodiment, the total mass percentage of each component of the electromagnetic shielding composite plastic is 100%. The specific formula is as follows: the matrix resin is polyphenylene sulfide, accounting for 68% by mass; the electromagnetic shielding filler accounts for 17% by mass; the reinforcing particles account for 14.75% by mass; and the antioxidant is a compound antioxidant, accounting for 0.25% by mass.

[0127] The composition details of the electromagnetic shielding filler are as follows: the conductive polymer is a mixture of polypyrrole and poly(3,4-ethylenedioxythiophene) in a mass ratio of 3:2, and the mass ratio of this mixture to the nano-carbon material is 3.5:1; the nano-carbon material consists of multi-walled carbon nanotubes and graphene nanosheets, with the multi-walled carbon nanotubes having an aspect ratio of 180 and the graphene nanosheets having a particle size of 18μm, in a mass ratio of 1.5:1; Ti3C2T X Modified with silane coupling agent KH-550, the treatment temperature was 98℃ and the treatment time was 55min, accounting for 11% of the total mass of the electromagnetic shielding filler; In the multi-layer graphene-coated carbonyl iron powder, the number of graphene coating layers was 8, the carbonyl iron powder particle size was 7μm, the ultrasonic-assisted coating power was 750W and the time was 2.8h, and this composite particle accounted for 7% of the total mass of the electromagnetic shielding filler.

[0128] The reinforcing particles consist of glass microspheres with a diameter of 18 μm and short-cut carbon fibers with a length of 0.45 mm, with a mass ratio of 2.8:1.

[0129] The raw materials were vacuum dried at 88℃ for 4.8 hours, with a moisture content of 0.045%. The electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 950 r / min for 14 min, followed by the addition of other components and continued mixing for 28 min. The twin-screw extruder was used to complete melt blending and granulation at a feeding section temperature of 188℃, a melting section temperature of 248℃, a homogenization section temperature of 258℃, a die head temperature of 252℃, and a screw speed of 480 r / min. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18 GHz frequency band was 50 dB, meeting the design requirement of ≥45 dB.

[0130] The parameters for injection molding step S2 are set as follows: barrel temperature 260℃, nozzle temperature 270℃, mold temperature 120℃, injection pressure 120MPa, holding pressure 82MPa, pulse holding cycle 2.9s, holding time 17s, and cooling time 42s. The combined ultraviolet-ozone treatment uses dual-band 185nm and 254nm ultraviolet light at an ozone concentration of 90mg / m³. 3 The process was carried out at 58℃ and 48% relative humidity for 14 minutes. Gradient metallization was performed by first electroless copper plating to a thickness of 2.8 μm, followed by vacuum magnetron sputtering of nickel to a thickness of 4.5 μm.

[0131] Test results show that the EMI shielding effectiveness of the package structure with gradient metallization layer in this embodiment is 64dB, the volume resistivity is 3.5Ω・cm, the thermal conductivity is 0.95W / (m・K), the coefficient of thermal expansion is 20.5ppm / ℃, the coating adhesion is grade 0, and the sealing performance meets the IP67 standard.

[0132] Comparative Example

[0133] Comparative Example 1 (No Gradient Metallization)

[0134] In this comparative example, the total mass percentage of all components in the electromagnetic shielding composite plastic is 100%, and the formulation is completely identical to that of Example 1: the matrix resin glass fiber reinforced PA66 accounts for 65%, the electromagnetic shielding filler accounts for 22%, the reinforcing particles account for 12%, the thermal conductivity regulating particles account for 0.7%, and the antioxidant accounts for 0.3%. The electromagnetic shielding filler contains 3 layers of graphene-coated carbonyl iron powder, and other component parameters are the same as in Example 1. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18GHz frequency band is 47dB, consistent with the performance of the plastic itself in Example 1, meeting the design requirement of ≥45dB.

[0135] The preparation process is the same as in Example 1: the raw material is vacuum dried at 90°C for 5 hours, the electromagnetic shielding filler is pre-dispersed at 1000 r / min for 15 minutes, and the twin-screw extrusion parameters are: feeding section 190°C, melting section 240°C, homogenization section 250°C, die head 245°C, and screw speed 400 r / min; the injection molding and encapsulation parameters are: barrel 250°C, nozzle 260°C, mold 105°C, injection pressure 100 MPa, holding pressure 70 MPa, pulse cycle 2.5 s, holding time 12 s, and cooling time 35 s; only the gradient metallization treatment is omitted after step S3, and the ultraviolet-ozone combined treatment is not performed.

[0136] Testing revealed that the EMI shielding effectiveness of the comparative example, which consisted only of a plastic body and lacked a gradient metallization layer, was 47 dB, consistent with the performance of the electromagnetic shielding composite plastic itself. While meeting the basic shielding requirement of ≥45 dB, it was significantly lower than the 62 dB of Example 1 with a gradient metallization layer, demonstrating the significant enhancement effect of gradient metallization on shielding effectiveness. The volume resistivity was 15 Ω·cm, higher than the 5 Ω·cm of Example 1 due to the absence of a metal layer for auxiliary conductivity. The thermal conductivity was 0.75 W / (m·K), slightly lower than that of Example 1. The coefficient of thermal expansion was 23 ppm / ℃, close to that of Example 1. Due to the lack of metal plating, there was no data on plating adhesion. Although the sealing performance met the IP67 standard, the overall electromagnetic shielding and conductivity were far inferior to that of Example 1.

[0137] Comparative Example 2 (without pulse-type pressure holding, electromagnetic shielding filler lacking Ti3C2T) X )

[0138] In this comparative example, the total mass percentage of all components in the electromagnetic shielding composite plastic is 100%, and the formula is adjusted as follows: the matrix resin polyphenylene sulfide accounts for 70%, the electromagnetic shielding filler accounts for 15%, the reinforcing particles account for 14.8%, and the antioxidant accounts for 0.2%; among which, Ti3C2T is removed from the electromagnetic shielding filler. XThe composition remained unchanged, with the remaining component ratios remaining the same: a 5:1 mass ratio of polypyrrole to nano-carbon materials, a 2:1 mass ratio of multi-walled carbon nanotubes to graphene nanosheets, and 3% of the total filler mass in multilayer graphene-coated carbonyl iron powder, with 4 graphene layers. Other filler parameters were the same as in Example 2. Individual testing showed that this electromagnetic shielding composite plastic achieved an EMI shielding effectiveness of 39dB in the 2-18GHz frequency band, below the design requirement of ≥45dB, demonstrating the effectiveness of Ti3C2T. X It plays a crucial role in the shielding performance of the plastic itself.

[0139] In the manufacturing process, the injection molding step S2 did not employ a pulsed holding pressure strategy, but only a constant holding pressure of 55 MPa and a holding time of 6 s. Other parameters were: barrel temperature 235°C, nozzle temperature 245°C, mold temperature 90°C, injection pressure 85 MPa, and cooling time 25 s. The gradient metallization and ultraviolet-ozone treatment parameters were consistent with those in Example 2, namely, chemical copper plating of 1 μm, magnetron sputtering of nickel of 1 μm, and ultraviolet-ozone treatment of 5 min, using dual-band ultraviolet light with wavelengths of 185 nm and 254 nm, at an ozone concentration of 50 mg / m³. 3 The process was carried out in an environment with a processing temperature of 40°C and a relative humidity of 30%; other processes such as raw material drying and twin-screw extrusion were the same as in Example 2.

[0140] Test results show that the EMI shielding effectiveness of the package structure with gradient metallization layer in this comparative example is 42dB, lower than the 58dB of Example 2. This is partly due to the lack of Ti3C2T in the plastic itself. X This results in insufficient basic shielding performance. On the other hand, the lack of pulsed pressure holding causes uneven dispersion of the filler inside the plastic, affecting the shielding effect. The volume resistivity is 12 Ω·cm, higher than 8 Ω·cm in Example 2. The thermal conductivity is 0.5 W / (m·K), lower than 0.6 W / (m·K) in Example 2, due to the uneven dispersion of the filler affecting the heat conduction path. The coefficient of thermal expansion is 28 ppm / ℃, higher than 25 ppm / ℃ in Example 2, due to the stress concentration inside the material caused by the lack of pulsed pressure holding, resulting in an increased coefficient of expansion. Although the coating adhesion is grade 0, the overall performance is significantly different from that of Example 2, and it cannot meet the requirements of mobile phone camera modules for blocking high-frequency strong interference.

[0141] Comparative Example 3 (raw material not vacuum dried, carbonyl iron powder without multi-layer graphene coating)

[0142] In this comparative example, the total mass percentage of all components in the electromagnetic shielding composite plastic is 100%, and the formula is adjusted as follows: 55% for the matrix resin glass fiber reinforced PA66, 30% for the electromagnetic shielding filler, 14.5% for the reinforcing particles, and 0.5% for the antioxidant; among them, the carbonyl iron powder component coated with multilayer graphene is removed from the electromagnetic shielding filler, while the proportions of the remaining components remain unchanged, i.e., the mass ratio of poly(3,4-ethylenedioxythiophene) to nano-carbon material is 1:1, the mass ratio of multi-walled carbon nanotubes to graphene nanosheets is 1:2, and Ti3C2T... X It accounts for 15% of the total mass of the filler, and other filler parameters are the same as in Example 3. Individual testing showed that the EMI shielding effectiveness of this electromagnetic shielding composite plastic in the 2-18GHz frequency band is 40dB, lower than the design requirement of ≥45dB, demonstrating the important role of multilayer graphene-coated carbonyl iron powder in the shielding performance of the plastic itself.

[0143] In the preparation process, the raw materials were not vacuum dried; the solid raw materials were directly mixed and fed into a twin-screw extruder, resulting in a raw material moisture content of 0.12%. Other preparation process parameters were the same as in Example 3, namely, the electromagnetic shielding filler was pre-dispersed in a high-speed mixer at 1200 r / min for 20 min; the twin-screw extrusion parameters were: feeding section 200°C, melting section 250°C, homogenization section 260°C, die head 255°C, and screw speed 500 r / min; the injection molding parameters were: barrel 265°C, nozzle 275°C, die 125°C, injection pressure 125 MPa, holding pressure 85 MPa, pulse cycle 3 s, holding time 18 s, and cooling time 45 s; the gradient metallization and ultraviolet-ozone treatment parameters were the same as in Example 3, namely, chemical copper plating 3 μm, magnetron sputtering nickel 5 μm, and ultraviolet-ozone treatment for 15 min, using dual-band ultraviolet light with wavelengths of 185 nm and 254 nm, at an ozone concentration of 100 mg / m³. 3 The process is carried out in an environment with a temperature of 60℃ and a relative humidity of 50%.

[0144] Testing revealed that the comparative example's encapsulation structure with a gradient metallization layer contained numerous microbubbles due to the raw materials not being fully dried. Its EMI shielding effectiveness was only 40dB, with the bubbles damaging the conductive and shielding network. Even with the metal layer, this could not effectively improve the shielding performance, far below the 65dB of Example 3. Its volume resistivity was 18Ω·cm, and its conductivity was inferior to 3Ω·cm of Example 3. Its thermal conductivity was 0.45W / (m·K), significantly lower than Example 3 due to the bubbles hindering heat conduction. Its coefficient of thermal expansion was 30ppm / ℃, higher than 20ppm / ℃ of Example 3, due to the bubbles causing uneven internal structure and reduced expansion stability. The coating adhesion was only Grade 1, as the undried raw materials reduced the surface smoothness of the plastic substrate, affecting the metal layer's adhesion. The sealing performance only reached IP65, with the bubbles causing leaks and failing to meet the waterproofing requirements of the mobile phone module. Overall, its performance was far inferior to Example 3.

[0145] Comparative Example 4 (Ordinary PA66 + UV-ozone treatment parameters did not meet standards)

[0146] In this comparative example, the total mass percentage of each component in the electromagnetic shielding composite plastic is 100%, and the formulation is adjusted as follows: the matrix resin is ordinary PA66, accounting for 60% by mass; the electromagnetic shielding filler accounts for 25% by mass, the same as in Example 4, i.e., the mass ratio of polyaniline to polypyrrole is 1:1, the mass ratio of this mixture to nano-carbon material is 4:1, the aspect ratio of multi-walled carbon nanotubes is 150, the particle size of graphene nanosheets is 15μm and the mass ratio of the two is 1:1, and Ti3C2T X The carbonyl iron powder, comprising 5 layers of multilayer graphene coating and accounting for 6% of the total filler mass, accounts for 12% of the total filler mass; the reinforcing particles account for 14.6% of the mass; the antioxidant accounts for 0.4%; other filler parameters are the same as in Example 4. Individual testing showed that this electromagnetic shielding composite plastic has an EMI shielding effectiveness of 49dB in the 2-18GHz frequency band, consistent with the performance of the plastic itself in Example 4, meeting the design requirement of ≥45dB.

[0147] In the preparation process, the parameters for the combined ultraviolet-ozone treatment did not meet the standards: only a single-band ultraviolet light with a wavelength of 254nm was used, without the auxiliary ozone generation of the 185nm band, resulting in an ozone concentration of 30mg / m³. 3 The processing temperature was 30℃, and the processing time was 3 min. Other parameters were the same as in Example 4, namely, the raw material was vacuum dried at 95℃ for 4.5 h, the electromagnetic shielding filler was pre-dispersed in a high-speed mixer at a speed of 1100 r / min for 18 min, and the twin-screw extrusion parameters were 195℃ for the feeding section, 245℃ for the melting section, 255℃ for the homogenization section, 250℃ for the die head, and 450 r / min for the screw speed. The injection molding parameters were 255℃ for the barrel, 265℃ for the nozzle, 115℃ for the mold, 110 MPa for the injection pressure, 75 MPa for the holding pressure, 2.8 s for the pulse cycle, 15 s for the holding time, and 40 s for the cooling time. The gradient metallization parameters were 2.5 μm of electroless copper plating and 4 μm of nickel plating by vacuum magnetron sputtering.

[0148] Test results show that the EMI shielding effectiveness of the encapsulation structure with gradient metallization layer in this comparative example is 45dB, lower than 63dB in Example 4. This is because the ultraviolet-ozone treatment is not up to standard, resulting in poor bonding between the metal layer and the plastic substrate, and some metal layers cannot effectively participate in shielding. In addition, the insufficient rigidity of ordinary PA66 affects the orientation of the filler. The volume resistivity is 10Ω·cm, higher than 4Ω·cm in Example 4. The thermal conductivity is 0.6W / (m·K), close to that of Example 4. The coefficient of thermal expansion is 32ppm / ℃, which is higher due to the poor thermal stability of ordinary PA66. The coating adhesion is level 2, which is due to insufficient activation of the substrate surface caused by insufficient ultraviolet-ozone treatment, making the metal layer easy to fall off. The sealing performance meets the IP67 standard, but the overall mechanical properties and electromagnetic shielding performance cannot meet the requirements of mobile phone camera modules, and the performance is significantly inferior to that of Example 4.

[0149] The performance comparison table of injection molding packaging for mobile phone camera modules is shown in Table 1 below.

[0150]

[0151] Table 1

[0152] Comparative Example 1 lacks coating adhesion data because it did not undergo gradient metallization treatment.

[0153] In the embodiments, the EMI shielding effectiveness of the electromagnetic shielding composite plastic tested individually was ≥45dB, which met the design requirements, and the effectiveness of the encapsulation structure with gradient metallization layer was improved to 58dB-65dB.

[0154] The comparative model demonstrates the characteristics of Ti3C2T by identifying the absence of key components or adjusting core processes. X The key performance characteristics of the method of the present invention are demonstrated by the multi-layer graphene-coated carbonyl iron powder, pulsed pressure holding, and ultraviolet-ozone treatment, and the fact that all performance characteristics are significantly inferior to those of the examples.

[0155] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for injection molding and packaging a mobile phone camera module, characterized in that, The method comprises the following steps: S1, fixing and preparation: providing a camera module assembly comprising a circuit board, an image sensor and a lens, positioning the camera module assembly on a bearing surface, applying negative pressure through a negative pressure air hole in communication with the bearing surface to adsorb and fix the camera module assembly; S2, integrated injection molding: closing the injection mold, injecting electromagnetic shielding composite plastic into the cavity, performing overmolding to form an integrated packaging structure that completely covers the circuit board and the image sensor and leaves out the lens light path; S3, post-processing and strengthening: after injection molding, release the negative pressure, demold, deburr, clean the packaging structure, and finish the installation reference surface.

2. The injection molding packaging method of a mobile phone camera module according to claim 1, characterized in that, The composition of the electromagnetic shielding composite plastic comprises: Base resin: glass fiber reinforced PA66 or polyphenylene sulfide, mass percentage 55%-70%; Electromagnetic shielding filler: mass percentage 15%-30%, containing conductive polymer, nano-carbon material and two-dimensional transition metal carbon nitride, wherein the mass ratio of conductive polymer to nano-carbon material is 5:1 to 1:1, and the two-dimensional transition metal carbon nitride accounts for 5%-15% of the total filler mass; Reinforcing particles: mass percentage 15%-25%, the reinforcing particles are a mixture of glass beads with a particle size of 5-20 μm and chopped carbon fibers with a length of 0.2-0.5 mm in a mass ratio of 1:1 to 3:1; Thermal regulation particles: mass percentage 0.5%-8%, particles compounded from aluminum nitride and silicon dioxide in a mass ratio of 2:1 to 4:1; Antioxidant: compounded antioxidant with a mass percentage of 0.2%-0.5%; The sum of the mass percentages of each component is 100%.

3. The injection molding packaging method of a mobile phone camera module according to claim 2, characterized in that: The electromagnetic shielding filler further comprises 3%-8% of multi-layer graphene-coated carbonyl iron powder based on the total mass of the electromagnetic shielding filler, wherein the number of graphene coating layers is 3-8, the particle size of the carbonyl iron powder is 1-10 μm, and the graphene coating process is carried out under ultrasonic assistance with an ultrasonic power of 500-800 W for 1-3 h.

4. The injection molding packaging method of a mobile phone camera module according to claim 2, characterized in that: The conductive polymer is at least one of polyaniline, polypyrrole or poly(3,4-ethylenedioxythiophene), and the nano-carbon material is a mixture of multi-walled carbon nanotubes and graphene nanosheets in a mass ratio of 1:2 to 2:1, and the length-diameter ratio of the multi-walled carbon nanotubes is 50-200, and the particle size of the graphene nanosheets is 5-20 μm.

5. The injection molding packaging method of a mobile phone camera module according to claim 2, characterized in that: Two-dimensional transition metal carbonitride is Ti3C2T X The surface is modified by silane coupling agent KH-550, the treatment temperature is 80-100 DEG C, and the treatment time is 30-60 min.

6. The injection molding packaging method of a mobile phone camera module according to claim 2, characterized in that: The electromagnetic interference shielding effectiveness of the electromagnetic shielding composite plastic is ≥45 dB in the frequency range of 2-18 GHz, and the volume resistivity is ≤10 Ω·cm, the thermal conductivity is ≥0.6 W / (m·K), and the thermal expansion coefficient is ≤25 ppm / ℃.

7. The injection molding packaging method of a mobile phone camera module according to claim 2, characterized in that: After step S3, gradient metallization is further performed on the outer surface of the packaging structure to build a composite electromagnetic shielding layer; The gradient metallization comprises: firstly, chemical copper plating with a thickness of 1-3 μm, and then vacuum magnetron sputtering of nickel with a thickness of 1-5 μm, to form a Cu / Ni double-layer structure, so that the overall EMI shielding effectiveness is improved to ≥58 dB; Before metal plating, the plastic substrate is subjected to ultraviolet-ozone combined treatment, and the treatment time is 5-15 min.

8. The injection molding packaging method of a mobile phone camera module according to claim 7, characterized in that, The specific conditions of the ultraviolet-ozone combined treatment are as follows: The surface of the encapsulated structure is activated by means of dual wavelength UV light at 185 nm and 254 nm in an ozone concentration of 50-100 mg / m 3 at a treatment temperature of 40-60 °C and a relative humidity of 30-50% for 5-15 minutes.

9. The injection molding method of claim 2, wherein, The injection molding process parameters of step S2 are as follows: The barrel temperature is 235-265℃, the nozzle temperature is 245-275℃, the mold temperature is 90-125℃, the injection pressure is 85-125 MPa, the holding pressure is 55-85 MPa, the holding time is 6-18 s, and the cooling time is 25-45 s; and a pulse type holding pressure strategy is adopted during the injection molding process.

10. The injection molding method of claim 2, wherein, The preparation method of the electromagnetic shielding composite plastic comprises: S2.1 all solid raw materials are vacuum dried at 80-100℃ for 4-6h, and the water content is controlled to ≤0.05%; S2.2 the electromagnetic shielding filler is pre-dispersed in a high-speed mixer, the rotating speed is 800-1200r / min, and the time is 10-20 min; S2.3 the base resin, reinforcing particles, heat-conducting adjusting particles and antioxidants are added, and the mixing is continued for 20-40 min; S2.4 the mixed material is sent into a double-screw extruder for melt blending and granulation, and the process parameters of the double-screw extruder are as follows: the feeding section temperature is 180-200℃, the melting section temperature is 230-250℃, the homogenizing section temperature is 240-260℃, the die temperature is 235-255℃, and the screw rotating speed is 300-500r / min.

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