A high-frequency high-speed high-Tg copper-clad plate, a preparation method and application thereof

Abstract

The application discloses a high-frequency high-speed high-Tg copper-clad plate and a preparation method and application thereof, and relates to the technical field of copper-clad plates.The application takes benzoxazine-urethane resin as a main body, compounding polyvinylidene fluoride, bismaleimide, butadiene styrene resin and bromostyrene, preferably hollow glass microbeads as fillers, and obtains the copper-clad plate by pressing the copper foil after preparing the prepreg through glue mixing and impregnation.The copper-clad plate prepared by the application has a dielectric constant of less than 3.0, a dielectric loss of less than 0.002 at 10GHz, a Tg of more than 240 DEG C, a T288 of more than 120min, a flame-retardant level of FV-0, and a peeling strength of more than 0.6N / mm, can effectively reduce signal transmission delay and distortion, and is suitable for the manufacture of printed circuit boards in the fields of 5G communication, AI servers, high-end data centers and the like.

Description

Technical Field

[0001] This invention relates to a high-frequency, high-speed, high-Tg copper-clad laminate, its preparation method, and its application, belonging to the field of copper-clad laminate technology. Background Technology

[0002] Copper clad laminate (CCL), as the core substrate of printed circuit boards (PCBs), forms the backbone of signal transmission in electronic devices. Its performance directly determines the signal integrity, thermal reliability, and mechanical stability of the PCB. CCLs are widely used in high-end electronic fields such as 5G communication, AI servers, high-end data centers, and automotive millimeter-wave radar. With the rapid development of the electronics industry towards higher frequencies, higher speeds, and smaller sizes, the required signal transmission frequencies have exceeded 10GHz, and transmission rates are moving towards 1.6Tbps and 3.2Tbps. This places more stringent requirements on the comprehensive performance of CCLs. Among these, glass transition temperature (Tg), dielectric constant (Dk), dielectric loss (Df), and peel strength have become core evaluation indicators. In particular, CCLs need to possess both high-frequency and high-speed transmission characteristics and high Tg heat resistance to meet the long-term stable operation requirements of high-end equipment.

[0003] In high-frequency and high-speed scenarios, the integrity of signal transmission is crucial. Low dielectric constant and low dielectric loss are key to reducing signal delay, signal distortion, and energy attenuation, while high Tg determines the dimensional stability and heat resistance reliability of copper-clad laminates under high-temperature conditions, avoiding problems such as circuit deformation and interlayer delamination caused by heat softening. At the same time, high peel strength ensures the strong bond between the copper foil and the resin matrix, improving product lifespan and processing reliability. Currently, the performance grades of high-frequency and high-speed copper-clad laminates in the industry have been upgraded from M7 to M8 and M9. Among them, M8 grade requires Dk < 3.0, Df ≤ 0.004, and Tg ≥ 180℃, while M9 grade requires Dk < 2.4, Df ≤ 0.0007, and Tg ≥ 200℃. However, copper-clad laminates prepared by existing technologies often fail to meet all of the above performance indicators, exhibiting significant technical shortcomings.

[0004] Existing high-frequency, high-speed copper-clad laminates primarily use epoxy resin, polyphenylene oxide (PPO), hydrocarbon resin, or bismaleimide triazine (BT) resin. Epoxy resin systems exhibit high dielectric loss (Df≈0.02-0.03) and low thermal expansion (Tg) (approximately 130-150℃), failing to meet the demands of high frequency, high speed, and high heat resistance. While PPO and hydrocarbon resin systems can reduce dielectric loss, they suffer from high cost, processing difficulties, poor compatibility with other components, and insufficient peel strength. BT resin systems struggle to simultaneously achieve synergistic improvements in low loss, low coefficient of thermal expansion, and high peel strength, and the introduction of epoxy resin increases the coefficient of thermal expansion, reducing product reliability. To improve performance, existing technologies often employ single resins or simple blending to adjust components, but this often results in trade-offs in performance; for example, increasing Tg leads to increased dielectric loss, while decreasing the dielectric constant sacrifices mechanical strength, failing to achieve comprehensive optimization of high frequency, high speed, high Tg, low loss, and high peel strength.

[0005] In terms of filler selection, the existing copper clad laminate industry mainly uses traditional inorganic fillers such as crystalline silica, fused silica, and talc to reduce the dielectric constant and improve thermal expansion performance. However, these traditional fillers have obvious defects: silica has high hardness (Mohs hardness 6-7), which will seriously wear down drills and milling cutters in PCB processing, increasing processing costs; talc (especially natural talc) has poor insulation performance and high oil absorption value, which will reduce the peel strength and adhesive compatibility of copper clad laminate; aluminum hydroxide has poor heat resistance and chemical resistance, which can easily lead to "white spot" defects in the board, limiting its usage. In addition, traditional fillers have a high density and are mostly solid structures, which cannot effectively reduce the overall dielectric constant of copper clad laminate, making it difficult to meet the control requirements of signal transmission delay and distortion in high-frequency and high-speed scenarios. At the same time, single fillers or simple mixed fillers are difficult to achieve the comprehensive requirements of high insulation, low dielectric loss and high peel strength. Moreover, the uneven particle size distribution of fillers can easily lead to poor dispersion, which further affects the thermal stability and interfacial bonding strength of copper clad laminate.

[0006] In summary, existing copper clad laminates have significant shortcomings in resin system selection, filler matching, and component synergy. They cannot simultaneously meet the comprehensive performance requirements of low dielectric constant (Dk < 3.0), low dielectric loss (Df < 0.002 at 10GHz), high Tg (> 240℃), high peel strength, and good coefficient of thermal expansion required for high-frequency and high-speed transmission. Consequently, they are ill-suited to the development needs of high-end electronic devices such as 5G high-end base stations, AI servers, and ultra-high-speed switches. Therefore, developing a high-frequency, high-speed, high-Tg copper clad laminate with reasonable composition and excellent comprehensive performance has become an urgent technical problem to be solved in the current copper clad laminate industry. Summary of the Invention

[0007] In this invention, the benzoxazine-urethane resin is consistent with the carboxylated graphene-reinforced poly(benzoxazine-urethane) nanocomposite resin disclosed in patent publication CN110885419B.

[0008] This invention addresses the shortcomings of existing copper-clad laminates (CCLs) in meeting the requirements of high-frequency, high-speed, and high-Tg dielectric constants (Tg). It provides a high-frequency, high-speed, and high-Tg CCL, its preparation method, and applications. The invention employs different component materials than existing high-frequency, high-speed CCLs, using carboxylated graphene-reinforced poly(benzoxazine-urethane) nanocomposite resin as the main resin. Polyvinylidene fluoride resin, bismaleimide resin, styrene-butadiene resin, and bromostyrene are added to adjust the resin ratio, increasing thermosetting properties while reducing dielectric loss. Furthermore, novel filler materials such as hollow glass microspheres can be added. These microspheres have a much lower density than traditional filler materials, and their hollow internal structure significantly reduces the overall dielectric constant of the CCL, decreasing signal delay and distortion during signal transmission. The resulting high-frequency CCL exhibits extremely low dielectric constant, reduced dielectric loss, and a good coefficient of thermal expansion, while also possessing high peel strength. The technical solution of this invention to solve the above-mentioned technical problems is as follows: A high-frequency, high-speed, high-Tg copper-clad laminate, the raw materials of which include the following components in parts by weight: 45-78 parts benzoxazine-urethane resin, 15-25 parts polyvinylidene fluoride resin, 17-30 parts bismaleimide resin, 20-35 parts styrene-butadiene resin, 20-35 parts bromostyrene, 0.5-1.5 parts curing agent and 55-75 parts filler.

[0009] More preferably, the raw materials comprise the following components in parts by weight: 48-71 parts benzoxazine-urethane resin, 15-24 parts polyvinylidene fluoride resin, 19-25 parts bismaleimide resin, 23-34 parts styrene-butadiene resin, 21-27 parts bromostyrene, 0.5-1.3 parts curing agent and 58-73 parts filler.

[0010] More preferably, the raw materials comprise the following components in parts by weight: 48 parts benzoxazine-urethane resin, 19 parts polyvinylidene fluoride resin, 19 parts bismaleimide resin, 23 parts styrene-butadiene resin, 24 parts bromostyrene, 0.5 parts curing agent and 69 parts filler.

[0011] Preferably, the curing agent is a phosphorus-containing curing agent.

[0012] Preferably, the filler is hollow glass microspheres.

[0013] Preferably, the high-frequency, high-speed, high-Tg copper-clad laminate also includes solvents as its raw material.

[0014] More preferably, the solvent includes toluene or butanone.

[0015] More preferably, the toluene content is 15-25 parts by weight; The content of the butanone is 25-40 parts by weight.

[0016] This invention also provides a method for preparing a high-frequency, high-speed, high-Tg copper-clad laminate as described above, comprising the following steps: (1) Mix and dissolve benzoxazine-urethane resin, polyvinylidene fluoride resin, bismaleimide resin, styrene-butadiene resin, bromostyrene, toluene and butanone to obtain a premix; (2) Mix the premix obtained in step (1) with the curing agent to obtain an intermediate mixture; (3) Mix the intermediate mixture obtained in step (2) with the filler to obtain the adhesive solution; (4) The low dielectric constant (Low Dk) electronic glass fiber cloth is impregnated with the adhesive obtained in step (3) to obtain a prepreg; (5) Cover the semi-cured sheet obtained in step (4) with copper foil to obtain a high-frequency, high-speed, high-Tg copper-clad laminate.

[0017] This invention also provides the application of the above-mentioned high-frequency, high-speed, high-Tg copper-clad laminate in the manufacture of printed circuit boards.

[0018] The beneficial effects of this invention are as follows: (1) The present invention uses benzoxazine-urethane resin as the main resin, and adds polyvinylidene fluoride resin, bismaleimide resin and styrene-butadiene resin to adjust the resin ratio and improve the crosslinking network, thereby reducing media loss. (2) The composition of the copper clad laminate adhesive in this invention is different from that of the high-frequency and high-speed copper clad laminates already on the market. This invention uses a new type of resin and a new type of filler hollow glass microspheres, whose density is much lower than that of traditional filler materials. The hollow structure inside can significantly reduce the overall dielectric constant of the copper clad laminate, reduce signal delay and signal distortion during signal transmission. The high-frequency copper clad laminate made has the advantages of extremely low dielectric constant, reduced dielectric loss, and good thermal expansion coefficient. At the same time, it can also improve the mechanical strength of the product, providing a new alternative method for the preparation of high-frequency and high-speed copper clad laminates. (3) The copper clad laminate provided by the present invention has a dielectric constant of <3.0, dielectric loss (10GHz) <0.002, Tg>240℃, T288>120 min, flame retardancy reaches FV-0 level, and peel strength>0.6N / mm. Detailed Implementation

[0019] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0021] In the specific embodiments of the present invention, the benzoxazine-urethane resin used is the carboxylated graphene-reinforced poly(benzoxazine-urethane) nanocomposite resin prepared in Example 9 of the patent publication text CN110885419B.

[0022] Example 1: A high-frequency, high-speed, high-Tg copper-clad laminate and its preparation method The method for preparing a high-frequency, high-speed, high-Tg copper-clad laminate includes the following steps: (1) At room temperature, by weight, add 48 parts of benzoxazine-urethane resin, 19 parts of polyvinylidene fluoride resin, 19 parts of bismaleimide resin, 23 parts of styrene-butadiene resin, 24 parts of bromostyrene, 17 parts of toluene solvent, and 35 parts of butanone solvent into a container and stir until fully dissolved. (2) At room temperature, add 0.5 parts by weight of phosphorus-containing curing agent to the mixture in step (1) and stir until it is fully dissolved; (3) By weight, 69 parts of hollow glass microspheres were added to the mixture in step (2) and stirred evenly to fully emulsify and obtain a glue solution; the glue solution gelled for 159s and the glue solution was uniform and stable. (4) The adhesive obtained in step (3) is evenly distributed on Low Dk fiberglass cloth and baked in an oven at 160°C for 4 minutes to obtain a semi-cured sheet; the semi-cured sheet has a uniform appearance and an adhesive content of 55%.

[0023] (5) Stack 6 semi-cured sheets obtained in step (4) according to requirements, cover both sides with 18-micron copper foil, and hot press in a vacuum press at a pressure of 5-17 MPa and a temperature of 160-210℃ for 3 hours and heat preservation for 1 hour to obtain a high-frequency high-speed copper-clad laminate.

[0024] Example 2 A method for preparing a high-frequency, high-speed, high-Tg copper-clad laminate includes the following steps: (1) At room temperature, by weight, add 71 parts of benzoxazine-urethane resin, 15 parts of polyvinylidene fluoride resin, 23 parts of bismaleimide resin, 34 parts of styrene-butadiene resin, 27 parts of bromostyrene, 20 parts of toluene solvent, and 27 parts of butanone solvent into a container and stir until fully dissolved. (2) At room temperature, add 1.3 parts by weight of phosphorus-containing curing agent to the mixture in step (1) and stir until it is fully dissolved; (3) By weight, 58 parts of hollow glass microspheres were added to the mixture in step (2) and stirred evenly to fully emulsify and obtain a glue solution; the gelation time of the glue solution was 168s, and the glue solution was uniform and stable. (4) The adhesive obtained in step (3) is evenly distributed on Low Dk fiberglass cloth and baked in an oven at 160°C for 5 minutes to obtain a semi-cured sheet; the semi-cured sheet has a uniform appearance and an adhesive content of 57%.

[0025] (5) Stack 6 semi-cured sheets obtained in step (4) according to requirements, cover both sides with 18-micron copper foil, and hot press in a vacuum press at a pressure of 5-17 MPa and a temperature of 160-210℃ for 3 hours and heat preservation for 1 hour to obtain a high-frequency high-speed copper-clad laminate.

[0026] Example 3 A method for preparing a high-frequency, high-speed, high-Tg copper-clad laminate includes the following steps: (1) At room temperature, by weight, 63 parts of benzoxazine-urethane resin, 24 parts of polyvinylidene fluoride resin, 25 parts of bismaleimide resin, 30 parts of styrene-butadiene resin, 21 parts of bromostyrene, 23 parts of toluene solvent, and 40 parts of butanone solvent are added to a container and stirred until fully dissolved. (2) At room temperature, add 0.7 parts by weight of phosphorus-containing curing agent to the mixture in step (1) and stir until it is fully dissolved; (3) By weight, 73 parts of hollow glass microspheres were added to the mixture in step (2) and stirred evenly to fully emulsify and obtain a glue solution; the gelation time of the glue solution was 173s, and the glue solution was uniform and stable. (4) The adhesive obtained in step (3) is evenly distributed on Low Dk fiberglass cloth and baked in an oven at 160°C for 6 minutes to obtain a semi-cured sheet; the semi-cured sheet has a uniform appearance and an adhesive content of 58%.

[0027] (5) Stack 6 semi-cured sheets obtained in step (4) according to requirements, cover both sides with 18-micron copper foil, and hot press in a vacuum press at a pressure of 5-17 MPa and a temperature of 160-210℃ for 3 hours and heat preservation for 1 hour to obtain a high-frequency high-speed copper-clad laminate.

[0028] Comparative Example 1 A method for preparing a copper-clad laminate includes the following steps: (1) Weigh the components of the adhesive solution according to the following weight parts: 19 parts epoxy resin, 85 parts bismaleimide resin, 0.3 parts dicyandiamide coupling agent, 75 parts butanone solvent, 0.03 parts phosphorus-containing curing agent and 55 parts silica powder filler, mix them thoroughly and stir evenly to obtain the adhesive solution. (2) The adhesive solution obtained in step (1) is completely and uniformly impregnated with ordinary fiberglass cloth, and baked in an oven at 200°C for 5 minutes to obtain a semi-cured sheet with an adhesive content of 50%; Four semi-cured sheets obtained in step (2) are stacked according to requirements, and 18-micron copper foil is covered on both sides. The copper-clad laminate is obtained by hot pressing in a vacuum press at a pressure of 5MPa and a temperature of 150℃ for 2 hours.

[0029] Comparative Example 2 A method for preparing a copper-clad laminate includes the following steps: (1) By weight, add 86 parts of benzoxazine-urethane resin, 23 parts of styrene-butadiene resin, 24 parts of bromostyrene, 17 parts of toluene solvent, and 35 parts of butanone solvent into a container and stir until fully dissolved; (2) At room temperature, add 0.5 parts by weight of phosphorus-containing curing agent to the mixture in step (1) and stir until it is fully dissolved; (3) By weight, 69 parts of hollow glass microspheres were added to the mixture in step (2) and stirred evenly to fully emulsify and obtain a glue solution; the glue solution gelled for 159s and the glue solution was uniform and stable. (4) The adhesive obtained in step (3) is evenly distributed on Low Dk fiberglass cloth and baked in an oven at 160°C for 4 minutes to obtain a semi-cured sheet; the semi-cured sheet has a uniform appearance and an adhesive content of 55%.

[0030] (5) Stack 6 semi-cured sheets obtained in step (4) according to requirements, cover both sides with 18-micron copper foil, and hot press in a vacuum press at a pressure of 5-17 MPa and a temperature of 160-210℃ for 3 hours and heat preservation for 1 hour to obtain a high-frequency high-speed copper-clad laminate.

[0031] The only difference between this comparative example and Example 1 is that the amounts of polyvinylidene fluoride resin and bismaleimide resin in the formulation are replaced with an equal amount of benzoxazine-urethane resin.

[0032] Comparative Example 3 A method for preparing a copper-clad laminate includes the following steps: (1) By weight, add 44 parts of benzoxazine-urethane resin, 14 parts of polyvinylidene fluoride resin, 32 parts of bismaleimide resin, 19 parts of styrene-butadiene resin, 24 parts of bromostyrene, 17 parts of toluene solvent, and 35 parts of butanone solvent into a container and stir until fully dissolved. (2) At room temperature, add 0.5 parts by weight of phosphorus-containing curing agent to the mixture in step (1) and stir until it is fully dissolved; (3) By weight, 69 parts of hollow glass microspheres were added to the mixture in step (2) and stirred evenly to fully emulsify and obtain a glue solution; the glue solution gelled for 159s and the glue solution was uniform and stable. (4) The adhesive obtained in step (3) is evenly distributed on Low Dk fiberglass cloth and baked in an oven at 160°C for 4 minutes to obtain a semi-cured sheet; the semi-cured sheet has a uniform appearance and an adhesive content of 55%.

[0033] (5) Stack 6 semi-cured sheets obtained in step (4) according to requirements, cover both sides with 18-micron copper foil, and hot press in a vacuum press at a pressure of 5-17 MPa and a temperature of 160-210℃ for 3 hours and heat preservation for 1 hour to obtain a high-frequency high-speed copper-clad laminate.

[0034] The only difference between this comparative example and Example 1 is that: The amount of benzoxazine-urethane resin was adjusted to 44 parts; The amount of polyvinylidene fluoride resin was adjusted to 14 parts; The amount of bismaleimide resin was adjusted to 32 parts; The amount of styrene-butadiene resin was adjusted to 19 parts.

[0035] Test case The products obtained in Examples 1-3 and Comparative Examples 1-3 were tested for dielectric constant, dielectric loss, Tg (DSC), T288 peel strength, and flame retardancy. The specific test items and methods are based on the following standards (sections): (1) Dielectric constant: GB / T 4722-2017-8.5; (2) Dielectric loss (10G): GB / T 4722-2017-8.5; (3) Tg (DSC): GB / T 4722-2017-6.7.1; (4) T288: GB / T 4722-2017-6.11; (5) Peel strength (N / mm): GB / T 4722-2017-7.2.1; (6) Flame retardancy: GB / T 4722-2017-6.4.1; The test data for each embodiment and comparative example are shown in Table 1.

[0036] Table 1. Test data for each embodiment and comparative example.

[0037] By comparing the test data in Table 1, it can be seen that the copper clad laminate of the embodiment has a dielectric constant of <3.0, dielectric loss (10G) <0.002, Tg >240℃, T288 >120min, flame retardancy reaches FV-0 level, and peel strength >0.6N / mm.

[0038] Based on the specific analysis of the above data, it can be confirmed that the embodiments provided by the present invention exhibit the following technical effects compared to existing copper-clad laminates: High-frequency dielectric performance optimization: In this embodiment of the invention, the dielectric constant is reduced from 3.88-4.51 to 2.88-2.94, and the dielectric loss under 10GHz conditions is reduced from 0.0098-0.0141 to 0.0018-0.0019. The dielectric parameters are significantly reduced, which can effectively reduce high-frequency signal transmission loss, reduce signal delay and distortion, and adapt to the use requirements of high-frequency and high-speed circuit boards. Improved heat resistance: This invention increases the glass transition temperature (Tg) of the material from 169-185℃ to 246-250℃; the thermal delamination time of T288 is increased from 55-60min to over 120min. The material's high-temperature delamination resistance and thermal dimensional stability are significantly enhanced, which can meet the requirements of high heat-resistant processing conditions such as lead-free soldering, and reduce the risk of high-temperature blistering and delamination failure of the board. Improved copper foil adhesion: The copper foil peel strength has been increased from 0.5-0.57 N / mm to 0.63-0.67 N / mm, resulting in a stronger bond between the copper foil and the substrate. This reduces the problem of copper foil peeling and falling off during processing and service, and improves the mechanical reliability of the product. Excellent flame retardant performance: While optimizing dielectric, heat resistance and adhesive properties, the flame retardant rating of this invention is maintained at the highest level of FV-0. There is no decay in flame retardant performance. It achieves synergistic optimization of multi-dimensional performance and does not have the defect of deterioration of other key indicators due to improvement of a single performance. The product has outstanding comprehensive application advantages.

[0039] In summary, compared with Comparative Examples 1-3, Examples 1-3 show significantly reduced dielectric constant and dielectric loss, and significantly improved Tg, T288 heat resistance, and copper foil peel strength; the flame retardant performance remains at FV-0 level without decline. Therefore, the improved copper-clad laminate of this invention has lower dielectric constant and dielectric loss than existing solutions, making it suitable for high-frequency applications, while other key performance indicators remain unchanged, achieving optimization and improvement in multiple aspects.

[0040] 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 high-frequency, high-speed, high-Tg copper-clad laminate, characterized in that, Its raw materials include the following components by weight: 45-78 parts benzoxazine-urethane resin, 15-25 parts polyvinylidene fluoride resin, 17-30 parts bismaleimide resin, 20-35 parts styrene-butadiene resin, 20-35 parts bromostyrene, 0.5-1.5 parts curing agent and 55-75 parts filler.

2. The high-frequency, high-speed, high-Tg copper-clad laminate according to claim 1, characterized in that, Its raw materials include the following components by weight: 48-71 parts benzoxazine-urethane resin, 15-24 parts polyvinylidene fluoride resin, 19-25 parts bismaleimide resin, 23-34 parts styrene-butadiene resin, 21-27 parts bromostyrene, 0.5-1.3 parts curing agent and 58-73 parts filler.

3. The high-frequency, high-speed, high-Tg copper-clad laminate according to claim 1, characterized in that, The curing agent is a phosphorus-containing curing agent.

4. The high-frequency, high-speed, high-Tg copper-clad laminate according to claim 1, characterized in that, The filler is hollow glass microspheres.

5. The high-frequency, high-speed, high-Tg copper-clad laminate according to claim 1, characterized in that, Its raw materials also include solvents; the solvents include toluene or butanone.

6. The high-frequency, high-speed, high-Tg copper-clad laminate according to claim 5, characterized in that, The toluene content is 15-25 parts by weight; The butanone is in the form of 25-40 parts by weight.

7. The method for preparing high-frequency, high-speed, high-Tg copper-clad laminate as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix and dissolve benzoxazine-urethane resin, polyvinylidene fluoride resin, bismaleimide resin, styrene-butadiene resin, bromostyrene, toluene and butanone to obtain a premix; (2) Mix the premix obtained in step (1) with the curing agent to obtain an intermediate mixture; (3) Mix the intermediate mixture obtained in step (2) with the filler to obtain the adhesive solution; (4) The low dielectric constant electronic glass fiber cloth is impregnated with the adhesive obtained in step (3) to obtain a semi-cured sheet; (5) Cover the semi-cured sheet obtained in step (4) with copper foil to obtain a high-frequency, high-speed, high-Tg copper-clad laminate.

8. The application of the high-frequency, high-speed, high-Tg copper-clad laminate as described in any one of claims 1-6 in the manufacture of printed circuit boards.

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