Modified polyurethane resin composition for high-frequency high-speed copper-clad plate, and preparation method and application thereof

Abstract

This invention belongs to the technical field of electronic chemicals and high-frequency, high-speed copper-clad laminate materials, specifically relating to modified polyurethane resin compositions for high-frequency, high-speed copper-clad laminates, their preparation methods, and applications. This invention constructs an oxazolidinone five-membered ring structure through the addition reaction of epoxy acrylate with a polyurethane prepolymer. This structure has low polarity and a small dipole moment, which can suppress orientation polarization and dipole loss under high-frequency electric fields at the molecular level. Simultaneously, combined with non-polar hydrogenated polybutadiene and fluorinated low-dielectric additives, and the synergistic effect of liquid crystal resin and surface-modified nano-silica, the composition exhibits good dielectric properties at 10 GHz, with significantly reduced dielectric constant and dielectric loss, making it suitable for low-loss scenarios in high-frequency, high-speed signal transmission.

Description

Technical Field

[0001] This invention relates to modified polyurethane resin compositions for high-frequency and high-speed copper-clad laminates, their preparation methods, and applications, belonging to the technical fields of electronic chemicals and high-frequency and high-speed copper-clad laminate materials. Background Technology

[0002] With the rapid development of 5G communication and high-speed computing technologies, the signal transmission frequency of electronic devices is constantly increasing, placing higher demands on the dielectric properties, thermal stability, and dimensional stability of copper-clad laminate (CCL) substrates. As a key basic material in the electronics and information industry, the performance of high-frequency, high-speed CCLs directly affects the integrity and reliability of signal transmission. Currently, commonly used CCL substrates include epoxy resin, polyimide, and polytetrafluoroethylene (PTFE), but these materials still have certain limitations in meeting the requirements of high-frequency, high-speed applications.

[0003] Polyurethane resins have shown promise in the field of copper-clad laminates (CCLs) due to their excellent mechanical and processing properties. However, the traditional polyurethane resin molecular structure contains a large number of polar groups, resulting in high dielectric constants and dielectric losses, making it difficult to meet the low dielectric performance requirements of high-frequency and high-speed circuits. To address this issue, researchers have explored various modification methods. For example, Chinese patent CN119119687B discloses a high-speed CCL prepared using functional plastics, which improves the dielectric properties and heat resistance of epoxy resin by adding a composition of PEEK micropowder and functional fillers. Chinese patent CN111363308B proposes an epoxy-modified low-dielectric fluorinated polyphenylene ether coating, which reduces the dielectric constant and dielectric loss by introducing a fluorinated polyphenylene ether structure into the epoxy resin.

[0004] In the research of low-dielectric materials, Chinese patent CN120116591B discloses a high-performance copper-clad laminate with low dielectric constant. It employs components such as epoxy resin, phenolic resin, polyphenylene ether modified resin, and modified nano-silica. Through the synergistic effect of fluorinated polyphenylene ether resin and modified nano-silica, it achieves both low dielectric constant and high heat resistance. Chinese patent CN119217811A introduces a copper-clad laminate that reduces the dielectric constant and increases the glass transition temperature by introducing cage-type polysilsesquioxane resin (POSS). Furthermore, Chinese patent CN111941960A discloses a halogen-free copper-clad laminate prepared using isocyanate-modified epoxy resin, benzoxazine resin, and phosphorus-containing phenolic resin curing agent, exhibiting a high glass transition temperature, excellent heat resistance, and low dielectric constant.

[0005] However, existing modified polyurethane resins still have the following shortcomings: First, existing modification technologies mostly focus on basic addition modification or conventional filler addition, failing to achieve low polarity optimization at the molecular structure level, making it difficult to fundamentally reduce dielectric constant and dielectric loss; second, there is a lack of synergistic compounding design of low dielectric functional components, making it impossible to simultaneously achieve multiple indicators such as low dielectric properties, low coefficient of thermal expansion, and high heat resistance; third, a single resin system is difficult to meet the comprehensive performance requirements of high-frequency and high-speed copper-clad laminates, as conventional polyurethane resin molecules have strong polarity and insufficient thermal and dimensional stability; finally, although polyurethane resins through simple compounding or conventional modification can partially improve mechanical properties, the high degree of polarization of molecular chain segments results in persistently high dielectric loss and a large coefficient of thermal expansion, making them prone to dimensional deformation at high temperatures, affecting the stability of circuit board signal transmission, and failing to meet the extreme performance requirements of 5G and high-end high-frequency and high-speed circuit boards for copper-clad laminate substrates.

[0006] Therefore, there is an urgent need to develop a modified polyurethane resin composition that can simultaneously achieve ultra-low dielectric properties, high heat resistance, and low coefficient of thermal expansion by starting with molecular structure design and through the synergistic effect of multiple components, in order to meet the application requirements of high-frequency and high-speed copper clad laminates. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a low-dielectric modified polyurethane resin composition for high-frequency and high-speed copper-clad laminates, its preparation method, and its application, thereby solving the technical problems of existing resin systems for high-frequency and high-speed copper-clad laminates, such as high dielectric constant, high dielectric loss, high coefficient of thermal expansion, low glass transition temperature, and insufficient copper foil peel strength, which are difficult to balance in terms of comprehensive performance.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-dielectric modified polyurethane resin composition for high-frequency and high-speed copper-clad laminates, comprising, by solid weight, the following components: 35-55 parts of epoxy acrylate modified polyurethane resin, 8-20 parts of hydrogenated polybutadiene, 20-28 parts of liquid crystal resin, 6-12 parts of nano-silica, 3-8 parts of crosslinking agent, 1-4 parts of curing agent, 0.1-2 parts of fluorine-containing low-dielectric additive, 0.5-3 parts of additive, 0.2-1.5 parts of free radical thermal initiator, and 40-65 parts of organic solvent. Preferably, the epoxy acrylate modified polyurethane resin is prepared by the following steps: (1) Heat the polyether polyol to 110-130℃ and dehydrate it under vacuum for 1-2 hours, cool it to 50-70℃, add toluene diisocyanate, control the molar ratio of isocyanate group to hydroxyl group to be 1.5-2.5:1, heat it to 85-95℃ and react it at a constant temperature for 2.5-3.5 hours; (2) Add epoxy acrylate, control the molar ratio of epoxy group to isocyanate group to be 0.3-0.8:1, add tertiary amine catalyst, heat to 90-110℃ and react for 2-3h to form oxazolidinone structure; (3) Cool to 20-25℃, filter, and add organic solvent to adjust the solid content to 60-80wt%.

[0009] The specific reaction formula is shown below: Step (1): Step (2):

[0010] In this invention, an oxazolidinone five-membered ring structure is formed by reacting epoxy acrylate with isocyanate groups. This structure has extremely low polarity and low dipole moment, which suppresses dipole polarization loss under high-frequency electric fields at the molecular level, significantly reducing dielectric constant and dielectric loss. By introducing hydrogenated polybutadiene, its non-polar saturated hydrocarbon structure is used to reduce the polarization degree of the overall system. By adding a high-ratio thermotropic aromatic polyester liquid crystal resin, it forms an ordered molecular arrangement in the resin system, significantly reducing the coefficient of thermal expansion and improving dimensional stability. By using nano-silica with a silane coupling agent surface treatment, it is uniformly dispersed in the resin matrix, filling the molecular gaps, reducing free volume, and suppressing the thermal motion and polarization of molecular chain segments. By adding a fluorinated low-dielectric additive, the surface energy and polarity of the system are further reduced, and water adsorption is reduced. By combining a crosslinking agent, curing agent, and free radical initiator to form a dense crosslinked network, the heat resistance, corrosion resistance, and mechanical properties of the cured resin are ensured.

[0011] Preferably, the polyether polyol is selected from polyether polyol N210 or N220, and the amount is 50-70 parts; the amount of toluene diisocyanate is 18-22 parts; and the amount of epoxy acrylate is 8-12 parts. Preferably, the hydrogenated polybutadiene is hydroxyl-terminated hydrogenated polybutadiene with a number-average molecular weight Mn of 1000-3000, a degree of hydrogenation ≥95%, and a functionality f of 1.8-2.2.

[0012] Preferably, the liquid crystal resin is a thermotropic aromatic polyester liquid crystal resin; the nano silica is nano silica that has been surface modified with a silane coupling agent and has a particle size of 30-50 nm.

[0013] Preferably, the crosslinking agent is isophorone diisocyanate and / or hexamethylene diisocyanate trimer; the curing agent is 2-ethyl-4-methylimidazole and / or 1-cyanoethyl-2-ethyl-4-methylimidazole; and the free radical thermal initiator is selected from dicumyl peroxide and benzoyl peroxide.

[0014] In this invention, an oxazolidinone five-membered ring structure is formed by reacting epoxy acrylate with isocyanate groups. This structure has extremely low polarity and low dipole moment, which suppresses dipole polarization loss under high-frequency electric fields at the molecular level, significantly reducing dielectric constant and dielectric loss. By introducing hydrogenated polybutadiene, its non-polar saturated hydrocarbon structure is used to reduce the polarization degree of the overall system. By adding a high-ratio thermotropic aromatic polyester liquid crystal resin, it forms an ordered molecular arrangement in the resin system, significantly reducing the coefficient of thermal expansion and improving dimensional stability. By using nano-silica with a silane coupling agent surface treatment, it is uniformly dispersed in the resin matrix, filling the molecular gaps, reducing free volume, and suppressing the thermal motion and polarization of molecular chain segments. By adding a fluorinated low-dielectric additive, the surface energy and polarity of the system are further reduced, and water adsorption is reduced. By combining a crosslinking agent, curing agent, and free radical initiator to form a dense crosslinked network, the heat resistance, corrosion resistance, and mechanical properties of the cured resin are ensured.

[0015] In a second aspect, the present invention provides a method for preparing a low-dielectric modified polyurethane resin composition as described in the first aspect, the preparation method comprising the following steps: (1) Premix: Epoxy acrylate modified polyurethane resin, hydrogenated polybutadiene, liquid crystal resin, nano silica, fluorine-containing low dielectric additives and auxiliaries are added to an organic solvent and dispersed for 30-60 min to obtain a premix. (2) Preparation of finished product: Add crosslinking agent, curing agent and free radical thermal initiator to the premix, stir continuously for 20-40 min, filter, and the low dielectric modified polyurethane resin composition is obtained. Thirdly, the present invention provides a prepreg, which is prepared by impregnating electronic-grade glass fiber cloth with the low-dielectric modified polyurethane resin composition described in the first aspect and baking it at 145-160°C for 4-6 minutes. Fourthly, the present invention provides a copper-clad laminate, which is prepared by the following steps: taking 4-8 sheets of the prepreg described in the third aspect, stacking them together, attaching copper foil to both the top and bottom surfaces, placing them in a vacuum hot press, preheating to 140-180°C, raising the temperature to 200-220°C within 4-6 minutes and holding it at that temperature for 90-120 minutes, and simultaneously raising the pressure to 1.0 MPa within 0.5-2 minutes and holding it at that pressure for 90-120 minutes, thereby pressing to obtain the copper-clad laminate.

[0016] Preferably, the copper-clad laminate has a dielectric constant Dk of 2.85-3.00, a dielectric loss Df of 0.00085-0.0011, a glass transition temperature Tg of 215-230℃, a Z-axis coefficient of thermal expansion CTE (50-260℃) of 1.80-2.10%, and a copper foil peel strength of 1.25-1.40 N / mm at a frequency of 10 GHz.

[0017] The copper-clad laminate prepared by this invention has a low dielectric constant and dielectric loss during high-frequency signal transmission, reducing signal transmission loss and delay. At the same time, it has a high glass transition temperature and a low longitudinal thermal expansion coefficient, ensuring dimensional stability and heat resistance reliability under high-temperature environments, as well as high copper foil peel strength, ensuring strong interlayer bonding. It is suitable for high-frequency and high-speed printed circuit boards in fields such as fifth-generation mobile communication and high-end servers.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs an oxazolidinone five-membered ring structure through the addition reaction of epoxy acrylate and polyurethane prepolymer. This structure has low polarity and small dipole moment, which can suppress orientation polarization and dipole loss under high-frequency electric fields at the molecular level. At the same time, it is combined with non-polar hydrogenated polybutadiene and fluorinated low dielectric additives, combined with the synergistic effect of liquid crystal resin and surface-modified nano-silica, so that the composition exhibits good dielectric properties at a high frequency of 10 GHz, with significantly reduced dielectric constant and dielectric loss, making it suitable for low-loss scenarios of high-frequency and high-speed signal transmission. Attached Figure Description

[0019] Figure 1 The image shows the FT-IR spectrum of epoxy acrylate modified polyurethane resin. Detailed Implementation The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] The sources of some of the raw materials in the examples are as follows: The polyether polyols N210 and N220 are products from Shandong Lanxing Dongda Chemical Co., Ltd., model numbers N210 and N220; the toluene diisocyanate is from BASF AG, model number TDI-100; the epoxy acrylate is from Changxing Chemical Industry Co., Ltd., model number EM221; the tertiary amine catalyst is triethylenediamine solution, specifically model A-33 (TEDA content 33%), from Momentive Advanced Materials Group / Huntsman Company; the hydrogenated polybutadiene is from Kuraray Co., Ltd., model number NISSO-PBG-1000. The product is G-2000; the saturated hydroxyl polyester resin is from BASF's Desmophen series; the thermotropic aromatic polyester liquid crystal resin is from Polyplastics Corporation of Japan, specifically the LAPEROS® E130i and Vectra® E130i products; the surface-modified nano silica is from Evonik Degussa, specifically the Aerosil® R7200 product; the isophorone diisocyanate is from BASF's Basonat® IPDI product; and the hexamethylene diisocyanate... The ester trimer is from Covestro, model number Desmodur® N3390; 2-ethyl-4-methylimidazolium is from BASF, model number 2E4MZ; 1-cyanoethyl-2-ethyl-4-methylimidazolium is from BASF, model number 2E4MZ-CN; the fluorinated acrylate leveling agent is from 3M / Chemours, model numbers Fluorad® FC-4430 and Capstone® FS-3100; the perfluoroalkyl silane surfactant is from Shin-Etsu Chemical Co., Ltd., model number X-71-195; leveling agents, disinfectants... The foaming agents, dispersants, and anti-settling agents are BYK-333 and TegoGlide410 products from BYK / Tego; dicumyl peroxide is PerkadoxBC-FF and 14S-FL products from AkzoNobel; organic solvents such as methyl ethyl ketone, toluene, and acetone are industrial-grade products from Jinan Century Tongda Chemical Co., Ltd.; electronic-grade glass fiber cloth is E-glass2116 and 1037 products from China Jushi Group / Taishan Fiberglass; and copper foil is TOB-DSP products from Jindu Company.

[0021] Example 1 1. Preparation of epoxy acrylate modified polyurethane resin (1) Add 60 parts of polyether polyol N210 to a dry reaction vessel, heat to 120℃ and dehydrate under vacuum for 1.5h, cool to 60℃, add 20 parts of toluene diisocyanate, control the molar ratio of NCO to OH to be 2.0:1, heat to 90℃ and react for 3h to obtain NCO-terminated polyurethane prepolymer; (2) Add 10 parts of epoxy acrylate, control the molar ratio of epoxy group to NCO group to be 0.5:1, add 0.03 parts of tertiary amine catalyst, heat to 100℃ and react for 2.5h to form oxazolidinone structure; (3) Cool to room temperature, filter to remove impurities, add methyl ethyl ketone to adjust the solid content to 70 wt%, and obtain epoxy acrylate modified polyurethane resin solution.

[0022] 2. Structural Characterization Fourier transform infrared spectroscopy was used to analyze the structure of the resin before and after modification, and the results are as follows: Figure 1 As shown, the characteristic absorption peak of the isocyanate group at 2270 cm⁻¹ disappeared after the polyurethane prepolymer reaction, indicating that the NCO group had completely reacted. At the same time, a strong carbonyl stretching vibration absorption peak appeared at 1740 to 1755 cm⁻¹, which is the characteristic absorption of the carbonyl group on the oxazolidinone ring. A moderate intensity CNC ring skeleton vibration peak appeared at 1380 to 1400 cm⁻¹. A moderate intensity COC ether bond vibration peak appeared at 1230 to 1250 cm⁻¹. The appearance of the above characteristic absorption peaks proves that the oxazolidinone structure was successfully formed.

[0023] 3. Resin composition (by solids weight) 45 parts of epoxy acrylate modified polyurethane resin 12 parts of hydrogenated polybutadiene 10 parts of saturated hydroxyl polyester resin 24 parts of thermotropic aromatic polyester liquid crystal resin 8 parts of surface-modified nano-silica (40nm) 5 parts of isophorone diisocyanate 2 parts of 2-ethyl-4-methylimidazol 1 part of fluorinated acrylate leveling agent Two parts of leveling agent and defoamer combined 2 parts of dicumyl peroxide 55 parts of a mixed solvent of methyl ethyl ketone and toluene 3. Preparation process (1) Add the above resin, liquid crystal resin, filler and additives to the mixed solvent and disperse at 2500 rpm for 45 min to obtain the premix; (2) Add crosslinking agent, curing agent and free radical thermal initiator to the premix, stir continuously for 30 min, and filter to obtain resin composition.

[0024] 4. Preparation of Prepreg and Copper Clad Laminate Prepreg is prepared by impregnating fiberglass cloth with resin solution and baking at 145℃ for 6 minutes. Six prepregs are then coated with copper foil on the top and bottom and vacuum hot-pressed: preheated at 160℃ for 5 minutes, then heated to 210℃ and held for 100 minutes, then heated to 1.0MPa and held for 100 minutes to obtain copper-clad laminate.

[0025] Example 2 1. Preparation of epoxy acrylate modified polyurethane resin (1) Add 70 parts of polyether polyol N220, dehydrate at 120℃ for 2h, cool to 60℃, add 18 parts of toluene diisocyanate, NCO to OH molar ratio 2.2:1, react at 92℃ for 3h to obtain the prepolymer; (2) Add 12 parts of epoxy acrylate, with an epoxy group to NCO molar ratio of 0.6:1, and react at 105℃ for 2 hours; (3) After purification, the solid content was adjusted to 72wt% to obtain the modified resin.

[0026] 2. Resin composition formulation (by solids weight) 50 parts of epoxy acrylate modified polyurethane resin 15 parts of hydrogenated polybutadiene 8 parts of saturated hydroxyl polyester resin 26 parts of thermotropic aromatic polyester liquid crystal resin 7 parts of surface-modified nano-silica (30nm) 4 parts of hexamethylene diisocyanate trimer 1.5 parts of 1-cyanoethyl-2-ethyl-4-methylimidazolium 0.8 parts of perfluoroalkylsilane surfactant The total amount of dispersant and anti-settling agent is 2.5 parts (m / m=1:1). 1 part dicumyl peroxide 50 parts of a mixed solvent of acetone and butanone 3. Preparation process (1) Add the above resin, liquid crystal resin, filler and additives to the mixed solvent and disperse at 1500 rpm for 45 min to obtain the premix; (2) Add crosslinking agent, curing agent and free radical thermal initiator to the premix, stir continuously for 30 min, and filter to obtain resin composition.

[0027] 4. Preparation of Prepreg and Copper Clad Laminate Prepreg is prepared by baking at 150℃ for 5 minutes. Six prepregs are then coated with copper foil on both the top and bottom. The mixture is then vacuum hot-pressed: the temperature is raised to 220℃ and held for 90 minutes after 5 minutes, and then raised to 1.0 MPa and held for 90 minutes after 1 minute to obtain a copper-clad laminate.

[0028] Example 3 1. Preparation of epoxy acrylate modified polyurethane resin (1) Add 50 parts of polyether polyol N210, dehydrate at 120℃ for 1h, cool to 60℃, add 22 parts of toluene diisocyanate, NCO to OH molar ratio 1.8:1, react at 88℃ for 3h to obtain the prepolymer; (2) Add 8 parts of epoxy acrylate, with an epoxy group to NCO molar ratio of 0.4:1, and react at 95℃ for 3h; (3) After purification, the solid content was adjusted to 68 wt% to obtain the modified resin.

[0029] 2. Resin composition formulation, based on solid parts by weight: 40 parts of epoxy acrylate modified polyurethane resin 10 parts hydrogenated polybutadiene 12 parts of saturated hydroxyl polyester resin 22 parts of thermotropic aromatic polyester liquid crystal resin 10 parts of surface-modified nano-silica (D=50nm) 6 parts of isophorone diisocyanate 3 parts of 2-ethyl-4-methylimidazol Fluorinated acrylate leveling agent 1.2 parts Defoamer and leveling agent total 1.5 parts (m:m=1:1) 3 parts of dicumyl peroxide 60 parts of toluene solvent 3. Preparation process (1) Add the above resin, liquid crystal resin, filler and additives to the mixed solvent and disperse at 3000 rpm for 45 min to obtain the premix; (2) Add crosslinking agent, curing agent and free radical thermal initiator to the premix, stir continuously for 30 min, and filter to obtain resin composition.

[0030] 4. Preparation of Prepreg and Copper Clad Laminate A semi-cured sheet was obtained by baking at 145℃ for 4 minutes. Five semi-cured sheets were then heated at 205℃ for 110 minutes and pressed at 1.0MPa for 110 minutes to obtain a copper-clad laminate.

[0031] Comparative Example 1 This comparative example provides a resin composition, a prepreg, and a copper-clad laminate, as well as a method for their preparation. The only difference from Example 1 is that hydrogenated polybutadiene is not added in this comparative example. The remaining components are proportionally allocated to the parts lacking hydrogenated polybutadiene. The other components, proportions, and processes are the same.

[0032] Comparative Example 2 Compared with Example 1, no thermotropic aromatic polyester liquid crystal resin was added, while the other components, proportions, and processes were the same, resulting in a resin composition, a prepreg, and a copper-clad laminate.

[0033] Comparative Example 3 Compared with Example 1, conventional unmodified polyurethane resin was used to replace epoxy acrylate modified polyurethane resin, while the other components, proportions, and processes were the same, to obtain resin composition, prepreg, and copper-clad laminate.

[0034] Comparative Example 4 Copper-clad laminates were prepared using commercially available bisphenol A type epoxy resin, methyltetrahydrophthalic anhydride curing agent, and benzyl dimethylamine accelerator, following conventional processes, and used as a commercially available comparison sample.

[0035] Test case The copper-clad laminates prepared in Examples 1-3 and Comparative Examples 1-4 were tested using the following methods: 1. Glass transition temperature (Tg) test The glass transition temperature of the resin system was determined using differential scanning calorimetry (DSC). The instrument used was a Q2000 DSC from TA Instruments Waters Corporation (USA). Test conditions were: nitrogen atmosphere, flow rate 50 mL / min, heating rate 10 °C / min, temperature range 25 °C to 300 °C. Samples of 5-10 mg were sealed in aluminum crucibles. The midpoint of the step-like transition in the second heating curve was taken as the glass transition temperature. This temperature reflects the transition of the resin system from the glassy state to the elastic state and is an important indicator for evaluating the heat resistance of copper-clad laminates.

[0036] 2. T288 Thermal Stratification Time Test The thermal mechanical analysis (TMA) method was used to determine the heat delamination resistance of copper-clad laminates (CCLs) at high temperatures. The testing instrument was a Q400 TMA from TA Instruments Waters Corporation (USA). Test conditions were: nitrogen atmosphere, heating rate of 10℃ / min to 288℃ followed by isothermal hold, constant pressure of 0.05 MPa, and a probe diameter of 1.0 mm. The time required for the sample thickness to change by more than 5% of the initial thickness was recorded as the T288 thermal delamination time. This indicator reflects the interlayer bonding stability of the CCL under high temperature and high humidity conditions; a longer time indicates better heat resistance.

[0037] 3. Coefficient of Thermal Expansion (CTE) Test The coefficient of thermal expansion (CTE) along the Z-axis of copper-clad laminates was determined using thermomechanical analysis (TMA). The testing instrument was a Q400 thermomechanical analyzer from TA Instruments Waters, USA. Test conditions were: nitrogen atmosphere, heating rate 5℃ / min, temperature range 50℃ to 260℃. Sample dimensions were 10mm × 10mm × copper-clad laminate thickness, and dimensional changes along the Z-axis were measured. The CTE value was calculated based on the average linear expansion coefficient within the temperature range of 50℃ to 260℃, expressed in ppm / ℃ or %. This indicator reflects the dimensional stability of the copper-clad laminate under temperature variations; a lower Z-axis CTE indicates better drilling processability and plating reliability.

[0038] 4. Solder heat resistance test A copper-clad laminate sample (50mm × 50mm) was immersed in molten solder at 288℃, and the time it took for the sample to delamination, blistering, or deformation to occur was observed and recorded. The testing equipment was a constant-temperature solder bath, with solder temperature fluctuations of ±2℃. This test simulates actual soldering process conditions to evaluate the instantaneous heat resistance of the copper-clad laminate.

[0039] 5. Copper foil peel strength test The bonding strength between copper foil and substrate was determined using a universal testing machine. The testing equipment was an Instron 5967 universal testing machine. The testing method was as follows: the copper-clad laminate was cut into 100mm × 25mm samples. Approximately 20mm was peeled off one end of the copper foil using a knife, and a 180° peel was performed at a tensile speed of 50mm / min. The peel force required per unit width was recorded, in N / mm.

[0040] 6. Dielectric constant (Dk) and dielectric loss (Df) testing The dielectric properties of copper-clad laminates at high frequencies were determined using a network analyzer. The testing instrument was a Keysight N5247B PNA-X vector network analyzer. The testing method was the split cylinder resonator method, with a test frequency of 10 GHz, a temperature of 23 ± 2 °C, and a relative humidity of 50 ± 5%. Sample dimensions were: diameter larger than the resonator diameter (typically ≥ 60 mm), thickness 0.5-2.0 mm, and a smooth, defect-free surface. The dielectric constant Dk reflects the material's ability to store electrical energy, while the dielectric loss Df reflects the degree of energy loss through heat conversion; lower values ​​for both are more beneficial for high-frequency signal transmission.

[0041] 7. Pencil Hardness Test The surface hardness of the cured resin coating was determined using the pencil scratch test. The testing instrument was a BYK-Gardner pencil hardness tester. The test method followed ASTM D3363 standard, using a high-grade drawing pencil (hardness 9B to 9H) from the Zhonghua brand, scratching the coating surface at a 45° angle with a 1kg load. The highest pencil hardness that did not scratch the coating was expressed as the highest hardness, in H.

[0042] All tests were conducted in accordance with the IPC TM-650 standard for copper clad laminates to ensure the accuracy and comparability of the test results. The test results are shown in Table 1. Table 1. Comprehensive performance test results of copper clad laminates in Examples 1-3 and Comparative Examples 1-4

[0043] Based on the comparison of test data from Examples 1-3 and Comparative Examples 1-4, the copper-clad laminate prepared by the low-dielectric modified polyurethane 172 resin composition of the present invention exhibits superior overall performance compared to conventional systems. The examples show better heat resistance indicators compared to Comparative Examples 1-3, indicating that the formulation and process of the present invention help improve the high-temperature stability of the material. The Z-axis thermal expansion coefficient of the examples is lower than that of Comparative Examples 1-3, thanks to the synergistic effect of the liquid crystal resin and nano-silica, which helps reduce high-temperature dimensional deformation. The copper foil peel strength of the examples is improved compared to Comparative Examples 1-3, with enhanced interface adhesion and mechanical reliability. At a frequency of 10 GHz, the dielectric constant and dielectric loss of the examples are lower than those of the comparative examples, making them suitable for high-frequency, high-speed transmission scenarios. The synergistic compounding of hydrogenated polybutadiene, liquid crystal resin, epoxy acrylate modified polyurethane, and nano-silica achieves better heat resistance, lower expansion, higher peel strength, and lower dielectric loss, which is superior to conventional compounding systems and has good industrial application value.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low dielectric modified polyurethane resin composition for high frequency high speed copper clad laminate, characterized by, Based on solid weight, it includes the following components: The composition includes 35-55 parts of epoxy acrylate modified polyurethane resin, 8-20 parts of hydrogenated polybutadiene, 20-28 parts of liquid crystal resin, 6-12 parts of nano silica, 3-8 parts of crosslinking agent, 1-4 parts of curing agent, 0.1-2 parts of fluorine-containing low dielectric additive, 0.5-3 parts of auxiliary agent, 0.2-1.5 parts of free radical thermal initiator, and 40-65 parts of organic solvent.

2. The low dielectric modified polyurethane resin composition according to claim 1, characterized by, The epoxy acrylate modified polyurethane resin is prepared by the following steps: (1) Heat the polyether polyol to 110-130℃ and dehydrate it under vacuum for 1-2 hours, cool it to 50-70℃, add toluene diisocyanate, control the molar ratio of isocyanate group to hydroxyl group to be 1.5-2.5:1, heat it to 85-95℃ and react it at a constant temperature for 2.5-3.5 hours; (2) Add epoxy acrylate, control the molar ratio of epoxy group to isocyanate group to be 0.3-0.8:1, add tertiary amine catalyst, heat to 90-110℃ and react for 2-3h to form oxazolidinone structure; (3) Cool to 20-25℃, filter, and add organic solvent to adjust the solid content to 60-80wt%.

3. The low-dielectric modified polyurethane resin composition according to claim 2, characterized in that, The polyether polyol is selected from polyether polyol N210 or N220, and the amount used is 50-70 parts. The amount of toluene diisocyanate used is 18-22 parts; The amount of epoxy acrylate used is 8-12 parts.

4. The low-dielectric-modified polyurethane resin composition according to claim 1, characterized in that, The hydrogenated polybutadiene is a hydroxyl-terminated hydrogenated polybutadiene with a number-average molecular weight (Mn) of 1000-3000, a degree of hydrogenation ≥95%, and a functionality (f) of 1.8-2.

2.

5. The low-dielectric-modified polyurethane resin composition according to claim 1, characterized in that, The liquid crystal resin is a thermotropic aromatic polyester type liquid crystal resin; The nano-silica is nano-silica that has been surface-modified with a silane coupling agent, and has a particle size of 30-50 nm.

6. The low-dielectric modified polyurethane resin composition according to claim 1, characterized in that, The crosslinking agent is isophorone diisocyanate and / or hexamethylene diisocyanate trimer; The curing agent is 2-ethyl-4-methylimidazol and / or 1-cyanoethyl-2-ethyl-4-methylimidazol; The free radical thermal initiator is selected from either dicumyl peroxide or benzoyl peroxide.

7. A method for preparing the low-dielectric modified polyurethane resin composition according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Premix: Epoxy acrylate modified polyurethane resin, hydrogenated polybutadiene, liquid crystal resin, nano silica, fluorine-containing low dielectric additives and auxiliaries are added to an organic solvent and dispersed for 30-60 min to obtain a premix. (2) Preparation of finished product: Add crosslinking agent, curing agent and free radical thermal initiator to the premix, stir continuously for 20-40 min, filter, and the low dielectric modified polyurethane resin composition is obtained.

8. A semi-cured sheet, characterized in that, The electronic-grade glass fiber cloth is impregnated with the low-dielectric modified polyurethane resin composition according to any one of claims 1-6 and baked at 145-160°C for 4-6 minutes.

9. A copper-clad laminate, characterized in that, The copper-clad laminate is prepared by the following steps: 4-8 sheets of the prepreg as described in claim 8 are stacked together, copper foil is attached to both the top and bottom surfaces, and the sheets are placed in a vacuum hot press. The press is first preheated to 140-180°C, then heated to 200-220°C within 4-6 minutes and held at that temperature for 90-120 minutes. Simultaneously, the pressure is increased to 1.0 MPa within 0.5-2 minutes and held at that pressure for 90-120 minutes to obtain the copper-clad laminate.

10. The copper-clad laminate according to claim 9, characterized in that, The copper-clad laminate has a dielectric constant Dk of 2.85-3.00, a dielectric loss Df of 0.00085-0.0011, a glass transition temperature Tg of 215-230℃, a Z-axis coefficient of thermal expansion CTE (50-260℃) of 1.80-2.10%, and a copper foil peel strength of 1.25-1.40 N / mm at a frequency of 10 GHz.

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