Preparation method of electromagnetic shielding composite material, composite material and chip test tray

Abstract

The application discloses a preparation method of an electromagnetic shielding composite material, a composite material and a chip test tray, and belongs to the technical field of semiconductor testing. The method comprises the following steps: providing a carbonizable resin precursor solution, adjusting the crosslinking degree of the precursor solution, introducing carbon fibers after the crosslinking degree is adjusted, and obtaining a mixed dispersion liquid; performing drying treatment on the mixed dispersion liquid to obtain a composite aerogel precursor; performing carbonization treatment on the composite aerogel precursor to obtain an electromagnetic shielding functional filler; and compounding the electromagnetic shielding functional filler with a polymer matrix to form a shape. Through the construction of the microstructure of the carbon fiber skeleton and the carbonized resin aerogel matrix composite, the application realizes efficient electromagnetic shielding, effectively suppresses the eddy current effect under high frequency, ensures the high-fidelity transmission of test signals, and has the advantages of light weight and good process adaptability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor testing technology, specifically relating to a method for preparing an electromagnetic shielding composite material, the composite material, and a chip testing tray. Background Technology

[0002] As chip operating frequencies and integration levels continue to increase, chips become extremely sensitive to the electromagnetic environment during testing. External electromagnetic interference can lead to test signal distortion and misinterpretation, while the electromagnetic radiation generated by the chip itself can also interfere with neighboring test units or equipment, affecting the efficiency and accuracy of parallel testing.

[0003] Currently, chip test trays on the market mainly use two types of material systems, both of which have significant technical limitations. One type is non-metallic trays represented by high-performance engineering plastics. Their core advantages lie in excellent electrical insulation, low density, ease of processing and molding, and low cost. However, their fundamental drawback is that they lack conductivity and cannot effectively shield or absorb electromagnetic waves. During testing, they cannot create a pure electromagnetic environment for the chip or prevent the leakage of chip radiation. This limits the application of this type of tray to low-frequency or low-precision testing fields where electromagnetic interference is not sensitive, restricting its application in high-frequency or high-precision testing fields and failing to meet the testing requirements of current mainstream high-performance chips. Secondly, metal trays made of materials such as aluminum alloy and stainless steel can provide a certain degree of electromagnetic shielding based on conductivity and the Faraday cage principle. However, the high density of metal results in a large tray weight, which exacerbates the load and wear on the robotic arm during high-speed, high-frequency picking and placing operations in automated testing equipment. More importantly, metal conductors generate parasitic inductance due to eddy current effects in high-frequency electromagnetic fields, forming parasitic capacitance with adjacent signal lines. This degrades the integrity of high-speed digital or radio frequency signals, introducing additional jitter, attenuation, and crosstalk, causing test results to fail to accurately reflect chip performance. Furthermore, improper grounding of all-metal structures poses a risk of static electricity accumulation and discharge, potentially damaging sensitive chips. Moreover, metal processing is complex, especially the cost of fabricating embedded fine circuits or complex cavities, and its coefficient of thermal expansion differs significantly from that of chip materials, potentially leading to poor contact due to stress during temperature cycling tests. Therefore, there is an urgent need for a novel chip test tray fabrication solution that simultaneously achieves efficient electromagnetic shielding, excellent high-frequency signal transmission characteristics, lightweight design, and good process adaptability. Summary of the Invention

[0004] This invention provides a method for preparing an electromagnetic shielding composite material, the composite material, and a chip test tray. The prepared electromagnetic shielding composite material is used in a chip test tray, achieving efficient electromagnetic shielding while avoiding signal distortion caused by eddy current effects, thus ensuring high-fidelity transmission of test signals.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing an electromagnetic shielding composite material includes the following steps: Step 1: Prepare a cross-linked resin solution; Step 2: Add carbon fiber to the resin solution obtained in step 1 and stir until it is evenly dispersed; Step 3: After pre-freezing the dispersion obtained in Step 2, vacuum freeze-dry it to obtain the composite carbon material aerogel precursor. Step 4: The composite carbon material aerogel precursor obtained in Step 3 is subjected to high-temperature carbonization treatment in an inert atmosphere; Step 5: Grind the carbonized product from Step 4 to obtain electromagnetic shielding powder; Step 6: Combine the carbon-based electromagnetic functional powder obtained in Step 5 with the polymer matrix to obtain an electromagnetic shielding composite material.

[0007] The specific process for preparing the crosslinked resin solution in the above steps is as follows: (1) Mix paraformaldehyde with deionized water and heat to carry out a prepolymerization reaction; (2) Add melamine to the mixed solution obtained in step 1 and stir until completely dissolved; (3) Adjust the pH value of the mixture obtained in step 2 to obtain a cross-linked resin solution;

[0008] The mass ratio of paraformaldehyde to deionized water is 1:3 to 1:5, preferably 1:4; the prepolymerization temperature is 70 to 100°C, the stirring speed is 280 to 320 rpm / min, and the prepolymerization time is 15 to 30 minutes.

[0009] The mass ratio of melamine to paraformaldehyde is 1:3.5 to 1:5, the stirring temperature is 70 to 100℃, and the stirring speed is 280 to 320 rpm / min.

[0010] Adjust the pH value to 7.0–8.0 to obtain a normally cross-linked resin solution; adjust the pH value to 8.0–9.0 to obtain an over-cross-linked resin solution.

[0011] In step 2, before adding carbon fiber (the proportion of carbon fiber is 10%-20% of the total mass of melamine and paraformaldehyde), stir thoroughly to ensure complete reaction.

[0012] In step 3, the pre-freezing temperature is -18℃ and the pre-freezing time is 48 h; the vacuum freeze-drying temperature is -60℃ and the drying time is 72 h.

[0013] In step 4, the high-temperature carbonization temperature is 500–1000℃, preferably 600–900℃; the time is 150–450 minutes, preferably 200–350 minutes.

[0014] The polymer matrix mentioned in step 6 includes one or more of epoxy resin, polyimide, and polyether ether ketone (PEEK); the electromagnetic shielding functional powder accounts for 50%-80% of the total mass.

[0015] The electromagnetic shielding composite material prepared by the above method includes a polymer matrix and an electromagnetic shielding functional powder dispersed in the polymer matrix. The electromagnetic shielding functional powder includes a carbon fiber skeleton and a carbonized resin aerogel loaded on the carbon fiber skeleton.

[0016] The aforementioned electromagnetic shielding composite material is used to prepare a chip test tray, which is provided with a receiving cavity and a wiring groove for placing chips.

[0017] Beneficial effects: This invention provides a method for preparing electromagnetic shielding composite materials, the composite material, and a chip testing tray, which have the following advantages compared with existing technologies:

[0018] 1. This invention constructs a microstructure combining a carbon fiber skeleton and a carbonized resin aerogel matrix, utilizing the excellent conductivity of carbon materials to achieve efficient electromagnetic shielding. At the same time, it significantly reduces the material density by leveraging the porous properties of aerogel, avoiding the mechanical load problems caused by the high density of traditional metal trays.

[0019] 2. This invention utilizes the excellent conductivity of carbon-based materials and the special microstructure formed by the composite to create a highly efficient conductive network within the material, thereby achieving effective shielding and reflection loss of electromagnetic waves, solving the problem of traditional engineering plastic pallets lacking electromagnetic shielding function.

[0020] 3. Through specific impedance matching design, the composite material of this invention effectively suppresses the generation of eddy current effect and parasitic parameters at high frequencies, solves the drawback of high-speed test signal distortion caused by metal trays, and ensures high-fidelity transmission of test signals.

[0021] 4. This invention combines good process adaptability with controllable manufacturing costs through injection molding. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the chip test tray fabrication process in Example 1;

[0023] Figure 2 The images show the carbon fiber aerogel precursor (a) and the electromagnetic shielding powder (b) prepared in Example 1.

[0024] Figure 3 Impedance matching of the electromagnetic functional powder prepared in Example 1;

[0025] Figure 4 The electromagnetic shielding effectiveness of the electromagnetic functional powder prepared in Example 1;

[0026] Figure 5 This is a photograph of the carbon fiber aerogel precursor prepared in Example 3;

[0027] Figure 6 Impedance matching of the over-crosslinked carbon fiber aerogel precursor prepared in Example 3 after carbonization treatment at 900°C;

[0028] Figure 7 The electromagnetic shielding effectiveness of the over-crosslinked carbon fiber aerogel precursor prepared in Example 3 after carbonization treatment at 900°C;

[0029] Figure 8 The electromagnetic shielding effectiveness of the carbon fiber aerogel precursor prepared in Example 4 after carbonization at 600°C;

[0030] Figure 9 The reflection loss capability of the carbon fiber aerogel precursor prepared in Example 4 after carbonization treatment at 600°C. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0032] Example 1:

[0033] like Figure 1 As shown, a method for preparing an electromagnetic shielding composite material specifically includes the following steps:

[0034] Step 1: Add 25.0g of paraformaldehyde and 100mL of deionized water to a beaker, place it on an 85℃ heating platform, and mechanically stir at 300rpm / min for 20 minutes.

[0035] Step 2: Add 6.00g of melamine to the solution in Step 1 and stir continuously at 85°C until completely dissolved.

[0036] Step 3: Continue to slowly add triethanolamine (0.5 mL each time) to the reaction mixture from Step 2 to adjust the pH. When the solution rapidly changes from turbid to clear (pH≈7.5), stop adding the triethanolamine to obtain a conventionally cross-linked melamine-formaldehyde resin system. Other thermosetting resins with high carbon residue, such as phenolic resin, urea-formaldehyde resin, or resorcinol-formaldehyde resin, are also suitable for this invention, as long as they can form a stable three-dimensional cross-linked network.

[0037] Adjusting the degree of crosslinking is one of the key steps in this embodiment. Its purpose is to control the degree of condensation of resin molecular chains, thereby determining the porosity and skeletal strength of the final aerogel matrix. If the crosslinking degree is too low, insufficient skeletal strength can easily lead to drying collapse; if the crosslinking degree is too high, the pore structure will be too dense, which is not conducive to subsequent impedance matching adjustment. Introducing carbon fibers after adjusting the crosslinking degree is to pre-construct a conductive skeletal structure in the aerogel matrix. As a one-dimensional nanomaterial, carbon fibers have an extremely high aspect ratio and excellent conductivity. Their uniform dispersion in the resin matrix can provide a high-speed electron transport channel for the subsequently carbonized material, thereby significantly improving the electromagnetic shielding effectiveness of the material.

[0038] Step 4: Stir the two mixtures for another 10 minutes to ensure complete reaction, then add 3.1 g of carbon fiber and continue stirring to disperse it evenly.

[0039] Step 5: Pre-freeze the obtained dispersion, and then perform vacuum freeze-drying to finally obtain the composite aerogel precursor;

[0040] In this embodiment, freeze-drying technology is preferred. Specifically, the mixed dispersion is pre-frozen in a low-temperature environment (e.g., a -18°C freezer) to allow the solvent to crystallize, followed by sublimation under vacuum to remove the ice crystals. This drying method maximizes the preservation of the resin's cross-linked porous structure, forming a lightweight, porous aerogel precursor. Depending on actual production conditions and cost considerations, supercritical drying or atmospheric pressure drying can also be used as alternatives, as long as solvent removal and maintenance of the framework structure are achieved.

[0041] Step 6: The aerogel precursor obtained in Step 5 is carbonized in a nitrogen atmosphere at a carbonization temperature of 900℃ for 300 min to obtain composite carbon fiber material.

[0042] Under an inert atmosphere (such as nitrogen or argon), the composite aerogel precursor undergoes high-temperature heat treatment. The resin matrix undergoes thermal decomposition, releasing non-carbon elements (such as hydrogen, oxygen, and nitrogen) in small molecule form. Carbon atoms rearrange to form a disordered graphite structure or a graphitized structure. This process not only endows the material with excellent conductivity but also further densifies the porous structure through volume shrinkage. The product after carbonization is a composite carbon material powder with electromagnetic shielding capabilities. This powder retains the porous characteristics of aerogel internally while being coated with a conductive carbon layer externally. This unique microstructure allows the material to possess high conductivity while having a density far lower than traditional metal powders. Furthermore, the porous structure effectively suppresses eddy current effects at high frequencies, preventing signal distortion.

[0043] Step 7: After grinding the composite carbon fiber material obtained in Step 6, electromagnetic functional material powder is obtained. The functional powder obtained after carbonization and grinding is then composited with epoxy resin through injection molding.

[0044] Example 2:

[0045] This embodiment provides a method for preparing an electromagnetic shielding composite material, including the following steps:

[0046] Step 1: Add 25.0g of paraformaldehyde and 100mL of deionized water to a beaker, place it on a 75℃ heating platform, and mechanically stir at 310rpm / min for 20 minutes.

[0047] Step 2: Add 5.80g of melamine to the solution in Step 1 and stir continuously at 75°C until completely dissolved.

[0048] Step 3: Continue to slowly add triethanolamine (0.5 mL each time) to the reaction mixture from Step 2 to adjust the pH. When the solution rapidly changes from turbid to clear (pH≈7.2), stop adding the triethanolamine to obtain a conventionally crosslinked resin solution.

[0049] Step 4: Stir the two mixtures for another 10 minutes to ensure complete reaction. Then add 3.08 g of carbon fiber and continue stirring to disperse it evenly.

[0050] Step 5: Pre-freeze the obtained dispersion in the freezer (-18℃), and then transfer it to a freeze dryer for vacuum freeze drying to finally obtain the composite aerogel precursor.

[0051] Step 6: The aerogel precursor obtained in Step 5 is carbonized in a nitrogen atmosphere at a temperature of 900℃ for 200 min to obtain composite carbon fiber material.

[0052] Step 7: After grinding the composite carbon fiber material obtained in Step 6, electromagnetic functional material powder is obtained. The functional powder obtained after carbonization and grinding is then combined with polyetheretherketone through injection molding to obtain an electromagnetic shielding functional composite material.

[0053] Example 3:

[0054] This embodiment provides a method for preparing an electromagnetic shielding composite material, including the following steps:

[0055] Step 1: Add 25.0g of paraformaldehyde and 100mL of deionized water to a beaker, place it on an 85℃ heating platform, and mechanically stir at 300rpm / min for 20 minutes.

[0056] Step 2: Add 6.10g of melamine to the solution in Step 1 and stir continuously at 85°C until completely dissolved.

[0057] Step 3: Continue to slowly add triethanolamine (0.5 mL each time) to the reaction mixture in Step 2 to adjust the pH. When the solution quickly changes from turbid to transparent (pH≈8.2), continue adding to obtain an over-crosslinked resin solution.

[0058] Step 4: Stir the two mixtures for another 10 minutes to ensure complete reaction. Then add 3.73 g of carbon fiber and continue stirring to disperse it evenly.

[0059] Step 5: Pre-freeze the obtained dispersion in the freezer (-18℃), and then transfer it to a freeze dryer for vacuum freeze drying to finally obtain the composite aerogel precursor.

[0060] Step 6: The aerogel precursor obtained in Step 5 is carbonized in a nitrogen atmosphere at a temperature of 900℃ for 300 min to obtain composite carbon fiber material.

[0061] Step 7: After grinding the composite carbon fiber material obtained in Step 6, electromagnetic functional material powder is obtained. The functional powder obtained after carbonization and grinding is then combined with epoxy resin through injection molding to obtain electromagnetic shielding functional composite material.

[0062] Example 4:

[0063] This embodiment provides a method for preparing an electromagnetic shielding composite material, specifically including the following steps:

[0064] Step 1: Add 25.0g of paraformaldehyde and 100mL of deionized water to a beaker, place it on an 85℃ heating platform, and mechanically stir at 280rpm / min for 20 minutes.

[0065] Step 2: Add 5.50g of melamine to the solution in Step 1 and stir continuously at 85°C until completely dissolved.

[0066] Step 3: Continue to slowly add triethanolamine (0.5 mL each time) to the reaction mixture from Step 2 to adjust the pH. When the solution rapidly changes from turbid to clear (pH≈7.7), stop adding the triethanolamine to obtain a conventionally crosslinked resin solution.

[0067] Step 4: Stir the two mixtures for another 10 minutes to ensure complete reaction. Then add 3.1 g of carbon fiber and continue stirring to disperse it evenly.

[0068] Step 5: The obtained dispersion was pre-frozen in a freezer (-18°C), and then transferred to a freeze dryer for vacuum freeze-drying to finally obtain the composite aerogel precursor.

[0069] Step 6: The aerogel precursor obtained in Step 5 is carbonized in a nitrogen atmosphere at a temperature of 600℃ for 250 min to obtain the composite carbon fiber material.

[0070] Step 7: After grinding the composite carbon fiber material obtained in Step 6, electromagnetic functional material powder is obtained. The functional powder obtained after carbonization and grinding is then combined with epoxy resin through injection molding to obtain electromagnetic shielding functional composite material.

[0071] To verify the effect of pH value on electromagnetic shielding performance Figure 2 A carbon fiber aerogel precursor prepared at a pH of approximately 7.5 was demonstrated, exhibiting a uniform structure. Figure 5 This study demonstrates an over-crosslinked aerogel precursor prepared at a pH of 8.2 (close to or exceeding the upper limit of the preferred range). While the solution becomes transparent at excessively high pH (e.g., 8.2), the excessively alkaline environment leads to an excessively rapid polycondensation reaction rate, causing the resin molecular chains to quickly entangle and become over-crosslinked, forming a denser but less elastic microstructure. This over-crosslinked structure exhibits significant performance differences in subsequent carbonization processes.

[0072] like Figure 3 and Figure 4 As shown, after carbonization at 900℃, the normally cross-linked sample (pH 7.5) exhibited excellent electromagnetic shielding effectiveness. In terms of total shielding effectiveness, the sample achieved full coverage of 30dB and 60dB in the 12.36-18.00GHz range, demonstrating excellent electromagnetic shielding capability. And as... Figure 6 and Figure 7 As shown, although the over-crosslinked (pH 8.2) sample still has a certain shielding ability, its overall shielding effectiveness is significantly lower than that of the normally crosslinked aerogel precursor. This is because the overly dense pore structure hinders the multiple reflections and absorptions of electromagnetic waves inside the material, and may also affect the interfacial bonding between carbon fiber and resin matrix.

[0073] Therefore, controlling the pH value within the range of 7.0-8.5, especially within the preferred range of 7.0-8.0, is a key process window for constructing an ideal microstructure and achieving efficient electromagnetic shielding. This parameter range ensures both sufficient dissolution and dispersion of the resin, while avoiding structural densification and performance degradation caused by excessive cross-linking.

[0074] To investigate the effect of carbonization temperature on the electromagnetic properties of the material, typical temperature points at the two ends of the temperature range (600℃ and 900℃) were selected for comparative experiments. Figure 3 and Figure 4As shown, when the carbonization temperature is set to 900℃, the sample exhibits extremely poor impedance matching characteristics. This means that electromagnetic waves are difficult to penetrate into the material and are absorbed, instead tending to be reflected at the material surface. Simultaneously, the sample achieves an electromagnetic shielding effectiveness exceeding 30dB in the 12.36-18.00 GHz frequency band, with the total shielding effectiveness primarily contributed by reflection shielding. This is because the high-temperature treatment induces a high degree of graphitization in the resin matrix, forming a complete conductive network and endowing the material with extremely high conductivity. This results in excellent electromagnetic shielding functionality based on the Faraday cage principle. This high conductivity and high shielding effectiveness are precisely what chip test trays urgently need for electromagnetic interference isolation.

[0075] like Figure 8 and Figure 9 As shown, when the carbonization temperature drops to 600℃, the electromagnetic response behavior of the material undergoes a fundamental reversal. Due to the lower temperature, the degree of graphitization of the resin is insufficient, resulting in decreased conductivity and significantly improved impedance matching characteristics. The shielding capability is drastically reduced, reaching a maximum of only 7dB. For the electromagnetic shielding composite material of this invention, selecting a high-temperature range of 500-1000℃, especially the 800-1000℃ range, is a necessary condition for achieving high graphitization, high conductivity, and efficient electromagnetic shielding. If the temperature is too low, the material will transform into an absorbing material, failing to meet the electromagnetic isolation requirements of the chip test tray.

[0076] Example 5:

[0077] This embodiment provides an electromagnetic shielding composite material, prepared by the method described in any one of embodiments 1 to 4 above; the electromagnetic shielding composite material includes a carbon fiber skeleton and a carbonized resin aerogel matrix loaded on the carbon fiber skeleton. Figure 2 As shown in Figure a, the precursor morphology after freeze-drying is illustrated. The sample surface appears gray, which is due to the mixture of white melamine-formaldehyde resin and black carbon fibers, with the carbon fibers uniformly dispersed in the resin matrix. After high-temperature carbonization, the resin matrix transforms into a hard carbon structure, while the carbon fibers retain their original fibrous morphology. In this microstructure, the carbon fiber skeleton plays a dual role: on the one hand, as a highly conductive one-dimensional material, the carbon fibers interlock within the material, constructing a through-type conductive network that provides a high-speed channel for electron transport. This is the physical basis for the material to achieve efficient electromagnetic shielding (mainly through reflection loss); on the other hand, as a reinforcing phase, the carbon fibers provide necessary support for the porous aerogel matrix, preventing the matrix from breaking under stress.

[0078] The carbonized resin aerogel matrix constitutes the main body of the material. This matrix inherits the three-dimensional porous network structure of the precursor aerogel, a structural feature crucial to the material's performance. First, the numerous pores significantly reduce the material's apparent density, making it far lighter than metal shielding materials of the same volume, thus resolving the issue of excessive weight on robotic arms caused by traditional metal trays. Second, the porous structure disrupts the continuity of conductive pathways, ensuring that while the material possesses high conductivity, it does not exhibit significant eddy current effects under high-frequency electromagnetic fields, unlike dense metals. This unique "conductive but not dense" characteristic allows the composite material to provide excellent electromagnetic shielding performance while effectively suppressing parasitic inductance and capacitance, avoiding distortion of high-frequency test signals. This resolves the technical contradiction between the "eddy current distortion" of metal trays and the "unshielded" nature of plastic trays in existing technologies.

[0079] Example 6:

[0080] This embodiment provides a chip test tray, which is made of the electromagnetic shielding composite material of Embodiment 5. The chip test tray is provided with a receiving cavity for placing the chip and a wiring groove. The receiving cavity is used to accurately position and fix the chip under test, and its size and shape are designed according to the specific chip package form (such as BGA, QFN, etc.). The wiring groove is used to arrange test signal lines, power lines and ground lines to ensure efficient transmission of test signals.

[0081] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, such as adjusting the formulation ratio of the precursor, replacing the polymer matrix with one of equivalent function, or changing the specific parameters of the carbonization process to adapt to different performance requirements, should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an electromagnetic shielding composite material, characterized in that, Includes the following steps: A carbonizable resin precursor solution is prepared, the degree of crosslinking of the precursor solution is adjusted, and carbon fibers are introduced after adjusting the degree of crosslinking to obtain a mixed dispersion. The mixed dispersion was dried to obtain a composite aerogel precursor; The composite aerogel precursor is carbonized to obtain an electromagnetic shielding filler. The electromagnetic shielding filler is combined with a polymer matrix to form the electromagnetic shielding composite material.

2. The method for preparing the electromagnetic shielding composite material according to claim 1, characterized in that, The process of adjusting the degree of crosslinking of the precursor solution is as follows: adjust the pH value of the precursor solution to 7.0-8.0 to control the degree of crosslinking of the resin.

3. The method for preparing the electromagnetic shielding composite material according to claim 1 or 2, characterized in that, The carbonizable resin precursor solution is prepared by mixing and stirring paraformaldehyde, melamine and solvent; the mass ratio of melamine to paraformaldehyde is 1:3.5-1:

5.

4. The method for preparing the electromagnetic shielding composite material according to claim 3, characterized in that, The amount of carbon fiber added is 10%-20% of the total mass of melamine and paraformaldehyde.

5. The method for preparing the electromagnetic shielding composite material according to claim 1, characterized in that, The mixed dispersion is pre-frozen before being dried.

6. The method for preparing the electromagnetic shielding composite material according to claim 1, characterized in that, The carbonization process is carried out at a temperature of 800-1000℃ for 150-450 minutes.

7. An electromagnetic shielding composite material, characterized in that, It is made by the method described in any one of claims 1 to 6.

8. The electromagnetic shielding composite material according to claim 7, characterized in that, It includes a polymer matrix and an electromagnetic shielding functional powder dispersed in the polymer matrix; the electromagnetic shielding functional powder includes a carbon fiber skeleton and a carbonized resin aerogel loaded on the carbon fiber skeleton.

9. A chip test tray, characterized in that, The chip test tray is made of the electromagnetic shielding composite material as described in any one of claims 7-8.

10. The chip test tray according to claim 9, characterized in that, The chip test tray is equipped with a receiving cavity and a wiring groove for placing chips.

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